Illustrated Medical Dictionary; Essential A-Z Quick Reference to over 5,500 Medical Terms - Dorling Kindersley DK Publishing ( PDFDrive )

S A LT SCAPULA

cancer of the ovary (see ovary, cancer scabies A skin infestation caused by the

of) or the uterus (see uterus, cancer of). mite SARCOPTES SCABIEI, which burrows

salt Commonly used to refer to sodium into the skin to lay eggs. Scabies is highly

chloride, a substance formed when an contagious by close physical contact

acid and base react. (See also saline.) and is most common in infants, chil-

salve A healing, soothing ointment. dren, and young adults.

sandfly bites Bites of small, long-legged The mite’s burrows appear on the skin

sandflies, found in many warm climates, as grey, scaly swellings, usually between

which can transmit disease to humans. the fingers, on the wrists and genitals,

In tropical and subtropical areas they and in the armpits. Later, reddish lumps

transmit leishmaniasis. In parts of Asia may appear on the limbs and trunk. The

and the Mediterranean, they transmit infestation causes intense itching, par-

sandfly fever, an influenza-like illness. ticularly at night. Treatment is with an

In the western Andes, they transmit bar- insecticide lotion.

tonellosis, different forms of which cause scald A burn due to hot liquid or steam.

either joint pain and fever, or a rash. scaling, dental Removal of dental cal-

sanitary protection Articles, such as culi (see calcuus, dental) from the teeth

pads and tampons, used to absorb blood to prevent or treat periodontal disease.

and protect clothing during menstruation. scalp The skin of the head, and its

saphenous vein A major vein that runs underlying tissue layers, that is normally

the length of the leg just under the skin. covered with hair. Scalp skin is tougher

It is sometimes removed and used to than other skin and is attached to an

bypass a blockage in blood vessels of underlying sheet of muscle that extends

the heart (see coronary artery bypass). from the eyebrows, over the top of the

sarcoidosis A rare disease of unknown head, to the nape of the neck. The scalp

cause in which there is inflammation of is richly supplied with blood vessels.

tissues throughout the body, especially Disorders affecting the scalp include

the lymph nodes, lungs, skin, eyes, and dandruff; alopecia; sebaceous cysts; pso-

liver. It occurs mainly in young adults. riasis; fungal infections such as tinea;

Symptoms do not always occur, but and parasitic infestations such as lice.

when they do, they include fever, gener- Cradle cap is common in infants.

alized aches, painful joints, and painful, scalpel A surgical knife for cutting tissue.

bloodshot eyes. Sarcoidosis may also scan An image produced by one of sev-

cause enlargement of the lymph nodes, eral scanning techniques.

breathlessness, erythema nodosum, a scanning techniques Methods of pro-

purplish facial rash, and areas of numb- ducing images of organ structure (or

ness. Possible complications include sometimes function) using sound waves,

hypercalcaemia, which may damage the radio waves, X-rays, or other forms of

S kidneys, and pulmonary fibrosis. radiation. Techniques include ultrasound,
Treatment of sarcoidosis is not always CT, radionuclide, MRI, and PET scanning

needed. Most people recover completely scaphoid One of the wrist bones. It is

within 2 years, with or without treat- the outermost bone on the thumb side

ment, but some develop a persistent, of the hand, in the row of wrist bones

chronic form of the disease. Cortico- nearest the elbow.

steroids are given to treat persistent A fracture of the scaphoid is a common

fever or erythema nodosum, to prevent wrist injury usually caused by a fall on an

blindness in an affected eye, and to outstretched hand. A characteristic symp-

reduce the risk of lung damage. tom is tenderness in the space between

sarcoma A cancer of connective tissue. the tendons at the base of the thumb

Types are osteosarcoma, Kaposi’s sarco- on the back of the hand. Treatment is by

ma, chondrosarcoma, and fibrosarcoma. immobilizing the wrist in a cast.

saturated fats See fats and oils; nutrition. scapula One of a pair of wing-shaped

scab A crust that forms on the skin or bones, commonly called the shoulder-

on a mucous membrane at the site of a blades, which are situated over the

healing wound or infected area. upper ribs at the back. The scapula

498

SCAR SCHIZOPHRENIA

SCAPULA schistosome A type of fluke. Three types
of schistosome are parasites of humans,
Clavicle Rib causing different forms of schistosomiasis.
Scapula Spine
Humerus schistosomiasis A parasitic tropical dis-
ease, caused by any of 3 species of flukes
serves as an attachment for certain called schistosomes, and acquired from S
muscles and tendons of the arm, neck, bathing in infested water. The larval form
chest, and back and is involved with penetrates the bather’s skin and develops
movements of the arm and shoulder. in the body into adult flukes, which settle
scar A mark left where damaged tissue in the veins of the bladder and intestines.
has healed. The body repairs a lesion by Eggs laid by adults provoke inflammatory
increasing collagen production at the site reactions; there may be bleeding and
of damage. If the edges of a lesion are ulceration in the bladder and intestinal
brought together during healing, a nar- walls, and the liver may also be affected.
row, pale scar forms; if the edges are left The first symptom is usually tingling
apart, more extensive scarring occurs. and an itchy rash where the flukes have
penetrated the skin. An influenza-like
A hypertrophic scar is a large, unsightly illness may develop weeks later, when
scar that sometimes develops at the site the adults produce eggs. Subsequent
of an infected wound; some people have symptoms include blood in the urine or
a family tendency to develop such scars. faeces, abdominal or lower back pain,
(See also adhesion; keloid.) and enlargement of the liver or spleen.
scarlatina Another name for scarlet fever. Complications of long-term infestation
scarlet fever An uncommon infectious include liver cirrhosis, bladder tumours,
disease, more often seen in childhood, and kidney failure. Treatment is with the
that is caused by a strain of streptococcal drug praziquantel.
bacteria. Symptoms include a severe sore
throat, high fever, vomiting, and a rash schizoid personality disorder Inabil-
of tiny red spots on the neck and upper ity to relate socially to other people.
trunk that spreads rapidly. The face is People with this trait, which is apparent
flushed, except around the mouth, and from childhood, are often described as
a white coating with red spots may deve- “loners” and have few, if any, friends.
lop on the tongue. This coating comes They are eccentric, seem to lack concern
off after a few days to reveal a bright red for others, and are apparently detached
colour. The fever then soon subsides, from normal day-to-day activities.
the rash fades, and the skin may peel.
schizophrenia A general term for a
As with other types of streptococcal group of psychotic illnesses that are
infections, rheumatic fever or glomeru- characterized by disturbances in think-
lonephritis may rarely develop 6 weeks ing, emotional reaction, and behaviour.
later. Treatment with antibiotics prevents Onset can be at any age but is most
this and promotes a rapid recovery. common in late adolescence and the
early 20s, and may be triggered by stress.
No causes have been identified, but
many have been implicated. It is likely
that inheritance plays a role. Disruption
of the activity of some neurotransmitters
in the brain is a possible mechanism.
Brain imaging techniques have revealed
abnormalities of structure and function
in people with schizophrenia.
Schizophrenia may begin insidiously,
with the individual becoming slowly
more withdrawn and losing motivation.
In other cases, the illness comes on
more suddenly, often in response to
external stress. The main symptoms are

499

SCIATICA SCOLIOSIS

various forms of delusions such as those The sciatic nerves SCIATIC NERVE
of persecution (which are typical of are formed from

paranoid schizophrenia); hallucinations, nerve roots in the Spinal
which are usually auditory (hearing spinal cord. cord

voices), but which may also be visual or scintigraphy An Spinal
tactile; and thought disorder, leading to alternative name nerve

impaired concentration and thought for radionuclide root

processes. Disordered thinking is often scanning.

reflected in muddled and disjointed scirrhous A term

speech. Behaviour is eccentric, and self- that means hard Sciatic

neglect common. In a rare form of and fibrous and is nerve

schizophrenia, catatonia may occur, in usually applied to

which rigid postures are adopted for malignant tumours

prolonged periods, or there are out- containing dense,

bursts of repeated movement. fibrous tissue.

Diagnosis of schizophrenia may take sclera The white

some time and, in some cases, it may fibrous outer coat

be difficult to make a diagnosis at all. that protects the

Treatment is mainly with antipsychotic eye from injury.

drugs, such as phenothiazine drugs, and The most com-

new atypical antipsychotic drugs such mon disorder of

as risperidone. In some cases, the drugs the sclera is scleritis. In osteogenesis

are given as monthly depot injections. imperfecta, the sclera is very thin.

Once the symptoms are controlled, scleritis Inflammation of the sclera that

community care, vocational opportu- usually accompanies a collagen disease

nities, and family counselling can help such as rheumatoid arthritis. Scleritis also

to prevent a relapse. occurs in herpes zoster ophthalmicus and

Some people may make a complete Wegener’s granulomatosis. It may lead to

recovery. However, the majority have areas of thinning and perforation of the

relapses punctuated with partial or full sclera. It is usually persistent but often

recovery. A small proportion have a responds to corticosteroid eye-drops.

severe life-long disability. scleroderma See systemic sclerosis.

sciatica Pain that radiates along the sci- scleromalacia Softening of the sclera,

atic nerve. The pain usually affects the commonly a complication of scleritis,

buttock and thigh, sometimes extending especially scleritis of rheumatoid arthritis.

down the leg to the foot. In severe cases, sclerosing cholangitis A rare condition

the pain may be accompanied by numb- in which many of the bile ducts are nar-

ness and/or weakness in the affected area. rowed, causing progressive liver damage

S The most common cause is a prolapsed for which the only treatment may be a
intervertebral disc pressing on the nerve liver transplant. (See also cholangitis.)

root (see disc prolapse). Other causes sclerosis A medical term for hardening

include a muscle spasm, sitting awkward- of a body tissue, usually used to refer to

ly for long periods, or, less commonly, hardening of blood vessels (as in arterio-

pressure on the nerve from a tumour. sclerosis) or of nerve tissue (as occurs in

Sometimes the cause is unknown. the later stages of multiple sclerosis).

Treatment of sciatica is with analgesic sclerotherapy A method of treating

drugs. If the pain is severe, a short per- varicose veins, especially in the legs;

iod of bed rest may be helpful, although haemorrhoids; and oesophageal varices.

prolonged rest may cause the condition The vein is injected with an irritant solu-

to worsen. Physiotherapy, osteopathy, or tion, which causes inflammation in the

chiropractic may help in some cases. It vessel lining, leading to scar tissue for-

is important to maintain a healthy mation and the obliteration of the vein.

posture and weight. scoliosis A deformity in which the spine

sciatic nerve The main nerve in each is bent to one side. The thoracic or lum-

leg and the largest nerve in the body. bar regions are most commonly affected.

500

SCORPION STINGS SEBACEOUS GLANDS

Scoliosis usually starts in childhood or of collagen, a protein in connective tissue, S
adolescence and becomes progressively causing weakness of small blood vessels
more marked until growth stops. In many and poor wound healing. Haemorrhages
cases, another part of the spine curves may occur anywhere in the body, includ-
to compensate, resulting in an S-shaped ing the brain. In the skin, haemorrhages
spine. The cause of juvenile scoliosis is result in bruising. Bleeding into the
unknown. Rarely, scoliosis is due to a gums and loosening of teeth are com-
congenital abnormality of the vertebrae. mon. Bleeding into muscles and joints
causes pain. Scurvy is treated with large
In some cases, physiotherapy may be doses of vitamin C. Bleeding stops in 24
sufficient to control scoliosis. Progressive hours, healing resumes, and muscle
or severe scoliosis may require immobi- and bone pain quickly disappear.
lization of the spine in a brace, followed sealants, dental Plastic coatings that
by surgery (spinal fusion) to straighten it. are applied to the chewing surfaces of
scorpion stings Injection of venom by a the back teeth to help prevent decay.
scorpion into a victim using a sting in its seasickness A type of motion sickness.
tail. Many species are not dangerous, seasonal affective disorder syndrome
but some in North Africa, southern US, A form of depression in which mood
South America, the Caribbean, and India changes occur with the seasons. Sufferers
are highly venomous. Some stings may tend to become depressed in winter and
cause only mild pain and tingling; but in feel better in spring. Exposure to bright
more venomous species severe pain, light for 2–4 hours each morning seems
restlessness, sweating, diarrhoea, and to prevent occurrence in some people.
vomiting can occur. Stings are rarely fatal sebaceous cyst A harmless smooth nod-
in adults but require prompt attention. If ule under the skin, most commonly on
pain is the only symptom, analgesics the scalp, face, ear, and genitals. The
and a cold compress may be enough. In cyst contains a yellow, cheesy material
severe cases, antivenom may be needed. and may become very large and infected
scotoma An area of abnormal vision by bacteria, making it painful. Large or
within the visual field. infected cysts can be surgically removed.
screening The testing of apparently sebaceous glands Glands in the skin
healthy people with the aim of detect- that secrete a lubricating substance called
ing disease at an early, treatable stage. sebum. Sebaceous glands either open
(See also cancer screening.)
scrofula Tuberculosis of the lymph nodes SEBACEOUS GLANDS
in the neck, often those just beneath the
angle of the jaw. Scrofula is rare in deve- Hair
loped countries. Antituberculous drugs
clear up the condition in most cases. Skin
scrotum The pouch that hangs behind surface
the penis and contains the testes. It con-
sists of an outer layer of thin, wrinkled Arrector pili
skin over a layer of muscular tissue. Swel- muscle
ling of the scrotum may be due to an
inguinal hernia, swollen testis, hydrocele, Sebum
or fluid accumulation due to heart failure.
scuba-diving medicine A medical spe- Sebaceous
ciality concerned with the physiological gland
hazards of diving with self-contained
underwater breathing apparatus. Most Hair
hazards stem from the pressure increase follicle
with depth. Conditions treated include
burst lung and decompression sickness. Fat
scurvy A disease, now rare in developed
countries, caused by inadequate vitamin
C intake. Scurvy disturbs the production

501

SEBORRHOEA SELF-IMAGE

into hair follicles or discharge directly excessive anxiety and to control danger-

on to the skin surface. They are most ously aggressive behaviour. It may also

numerous on the scalp, face, and anus be used as part of premedication.

and are absent from the palms and soles sedative drugs A group of drugs used

of the feet. Sebum production is partly to produce sedation. Sedative drugs in-

controlled by androgen hormones. Dis- clude sleeping drugs, antianxiety drugs,

orders of the sebaceous glands may antipsychotic drugs, and some antide-

lead to seborrhoea or acne vulgaris. pressant drugs. A sedative drug is often

seborrhoea Excessive secretion of included in a premedication.

sebum, causing oiliness of the face and seizure A sudden episode of abnormal

a greasy scalp. The cause is unclear, but electrical activity in the brain. Recurrent

androgen hormones play a part. Sebor- seizures occur in epilepsy.

rhoea is most common in adolescent Seizures may be partial or generalized.

boys; those affected are more likely to In a partial seizure, the abnormal activity

develop seborrhoeic dermatitis and acne is confined to one area of the brain.

vulgaris. The condition usually improves Symptoms include tingling or twitching

in adulthood without treatment. of a small area of the body, hallucinations,

seborrhoeic dermatitis See dermatitis. fear, or déjà vu. In a generalized seizure,

sebum The oily secretion produced by the abnormal activity spreads through

the sebaceous glands of the skin. Sebum the brain, causing loss of consciousness.

lubricates the skin, keeps it supple, and Causes of seizures include head injury,

protects it from becoming waterlogged stroke, brain tumour, infection, metab-

or dried out and cracked. It also protects olic disturbances, withdrawal in alcohol

the skin from invasion by bacteria and dependence, or hereditary alcohol intol-

fungi. Oversecretion of sebum (see seb- erance. In children, high fever may cause

orrhoea) causes greasy skin and may seizures. Anticonvulsant drugs can con-

lead to seborrhoeic dermatitis or acne. trol seizures or reduce their frequency.

secondary A term applied to a disease selective serotonin reuptake inhib-

or disorder that results from or follows itors (SSRIs) A relatively new class of

another disease (the primary disease). drugs that are used to treat depression.

It also refers to a malignant tumour that They work by blocking the reabsorption

has spread from a primary cancer else- of the neurotransmitter serotonin follow-

where in the body (see metastasis). ing its release in the brain. The increased

secretin A hormone produced by the serotonin levels that result are associa-

duodenum when acidic food enters it ted with improved mood. Common drugs

from the stomach. Secretin stimulates in this group include fluoxetine and ser-

the release of pancreatic juice, which traline. SSRIs are usually taken orally

contains bicarbonate to neutralize the once a day; it may take 1–3 weeks for any

S acid, and bile from the liver. noticeable improvement in symptoms.
secretion The manufacture and release SSRIs usually produce fewer side effects

by a cell, gland, or organ of substances, than other types of antidepressant drug.

(such as enzymes) needed for metabolic However, they may cause diarrhoea,

processes elsewhere in the body. nausea, restlessness, and anxiety.

secretory otitis media An alternative selenium A trace element that may help

name for glue ear. to preserve the elasticity of body tis-

sectioning A commonly used term to sues. The richest sources are meat, fish,

describe the implementation of a sec- whole grains, and dairy products.

tion of the Mental Health Act. self-help organizations Organizations,

security object A significant item, such usually set up by patients or their rel-

as a favourite soft toy, that provides atives, that provide people affected by

comfort and reassurance to a young particular conditions with information,

child. Attachment to such an item is nor- support, and, sometimes, financial aid.

mal and usually diminishes by age 7 or 8. self-image A person’s view of his or her

sedation The use of a drug to calm a own personality and abilities. Some neu-

person. Sedation is used to reduce rotic disorders stem from an incongruity

502

SELF-INJURY SENSATION

between self-image and how others see SEMINAL VESICLE
one. Psychotherapy treats neurosis by
changing a person’s self-image. Urethra Bladder Vas deferens Ureter
self-injury The act of deliberately injur-
ing oneself. Self-mutilation most often Epididymis Ejaculatory Seminal
occurs in young adults, many of whom duct vesicle
are also drug or alcohol abusers, and is 3
times more common in women. It may and produce seminal fluid, which is S
take the form of cutting the wrists or mixed with sperm to make up semen
burning the forearms with cigarettes. In (see reproductive system, male).
some, it is a means of dealing with stress, seminoma See testis, cancer of.
such as that caused by child abuse. senile dementia See dementia.
senile purpura A skin condition in which
More unusual forms of self-harm, such areas of the skin develop a purplish or
as mutilating the genitals, are usually reddish-brown appearance due to bleed-
due to psychosis. Self-destructive biting ing of small blood vessels underneath.
is a feature of Lesch–Nyhan syndrome, Senile purpura is a disease of middle to
a rare metabolic disorder. old age and is more common in women.
selegiline A drug used in the treatment senility A term meaning old age or, more
of Parkinson’s disease, either alone (in commonly, the decline in mental ability
the disease’s early stage) or with levo- that may occur in old age.
dopa. Selegiline is also used to treat the senna A laxative drug obtained from the
symptoms of parkinsonism due, for ex- leaves and pods of the Arabian shrubs
ample, to repeated head injury; it is not CASSIA ACUTIFOLIA and CASSIA ANGUSTIFO-
used if the symptoms are drug-induced, LIA, which stimulates bowel contractions.
however. Side effects may include nau- It may colour the urine brown or red.
sea, vomiting, diarrhoea or constipation, sensate-focus technique A method
dry mouth, and sore throat. taught to couples who are experiencing
semen Fluid produced by the male on sexual difficulties caused by psycholog-
ejaculation. It is composed of fluid from ical rather than physiological factors. The
the seminal vesicles, fluid from the pros- aim of the technique is to make both
tate and Cowper’s glands, and sperm. partners more aware of pleasurable
semen, blood in the A usually harmless bodily sensations, and to reduce anxi-
condition in which a small amount of ety about performance. It is particularly
blood is present in the semen. Occasion- effective in treating loss of sexual desire
ally, there is an underlying cause (such as (see sexual desire, inhibited), or inability
an infection or, very rarely, cancer) that to achieve orgasm (see orgasm, lack of),
requires treatment. Blood in the semen and in helping men to overcome impo-
may also occur after a prostate biopsy. tence or premature ejaculation (see
semicircular canal A structure in the ejaculation, disorders of).
inner ear that plays a role in balance. sensation A feeling or impression that
There are 3 semicircular canals in each has entered consciousness. The senses
ear, at right angles to each other, and convey information, about the external
connected via a chamber called the
vestibule. The fluid-filled canals contain
small hairs that detect movement and
acceleration, and transmit information
to the brain via the vestibular nerve.
seminal fluid analysis Analysis of
sperm concentration, shape, and motility
(ability to move). It is used to investigate
male infertility and is also done some
weeks after vasectomy to ensure that
the semen no longer contains sperm.
seminal vesicle One of a pair of sacs
that lie behind the bladder in the male

503

SENSATION, ABNORMAL SEPTICAEMIA

environment and about the body’s inter- perceived in the occipital lobes at the

nal state, to the central nervous system. back of the cerebrum; sound is perceived

Information is collected by millions of in the temporal lobes at the sides.

sense receptors found throughout body sensory deprivation The removal of

tissues and in special sense organs, such normal external stimuli, such as sight

as the eye. Certain sensory information, and sound, from a person’s environment.

mainly that from the special sense Prolonged sensory deprivation can pro-

organs and skin receptors, enters the sen- duce feelings of unreality, difficulty in

sory cortex of the brain, where sensations thinking, and hallucinations.

are consciously perceived. Other types of separation anxiety The feelings of

sensory information, for example about distress a young child experiences when

body posture, are processed elsewhere parted from his or her parents or home.

and do not produce conscious sensation. This is a normal aspect of infant behav-

sensation, abnormal Dulled, unpleas- iour and usually diminishes by age 3 or 4.

ant, or otherwise altered sensations in In separation anxiety disorder, the

the absence of an obvious stimulus. reaction to separation is greater than

Numbness and pins-and-needles are that expected for the child’s level of de-

common abnormal sensations. The spe- velopment. The anxiety may manifest as

cial senses can be impaired by damage physical symptoms. Separation anxiety

to the relevant sensory apparatus (see disorder may be a feature of depression.

vision, disorders of; smell; deafness; tinni- sepsis Infection of a wound or body tis-

tus). Other causes of abnormal sensation sues with bacteria that leads to the

include peripheral nerve damage caused formation of pus or to the multiplication

by diabetes mellitus, herpes zoster infec- of the bacteria in the blood. (See also

tion, or pressure from a tumour, and bacteraemia; septicaemia; septic shock.)

disruption of nerve pathways in the brain septal defect A congenital heart abnor-

or spinal cord due to spinal injury, head mality in which there is a hole in the

injury, stroke, and multiple sclerosis. septum between the left and right ven-

Pressure on or damage to nerves can tricles of the heart or, more rarely,

sometimes be relieved by surgery or by between the left and right atria. Usually,

treatments for the cause. In other cases, the cause is unknown. The hole allows

distressing abnormal sensation can be freshly oxygenated blood to mix with

relieved only by cutting the relevant nerve deoxygenated blood in the heart.

fibres or by giving injections to block A small defect has little or no effect. A

the transmission of signals. large ventricular hole may cause heart

senses See sensation. failure to develop 6–8 weeks after birth,

sensitization The initial exposure of a causing breathlessness and feeding dif-

person to an allergen or other substance ficulties. A large atrial defect may never

S recognized as foreign by the immune cause heart failure, but there may be
system, which leads to an immune res- fatigue on exertion. Pulmonary hyperten-

ponse. On subsequent exposures to the sion may develop in both types of defect.

same substance, there is a much stronger Diagnosis may be aided by a chest

and faster immune reaction. This forms X-ray, ECG, or echocardiography.

the basis of allergy and other types of Atrial holes are repaired surgically if

hypersensitivity reaction. they cause symptoms or if complications

sensorineural deafness Deafness due develop. As the child grows, small ven-

to problems with the inner ear, nerves, tricular holes often become smaller, or

or the brain’s auditory area. even close, on their own. A ventricular

sensory cortex A region of the outer defect that is causing heart failure is

cerebrum of the brain in which sensory treated with diuretics and digitalis drugs.

information comes to consciousness. If the hole does not close spontaneously,

Pressure, pain, and temperature sen- it may be repaired by open heart surgery.

sations from the skin, muscles, joints, septicaemia A potentially life-threaten-

and organs are perceived in the parietal ing condition in which there is rapid

lobes, as is taste. Visual sensations are multiplication of bacteria and in which

504

SEPTIC ARTHRITIS SERUM SICKNESS

bacterial toxins are present in the serotonin A substance found in many S
blood. (See also bacteraemia.) tissues, particularly blood platelets, the
digestive tract lining, and the brain. Sero-
Septicaemia usually arises through es- tonin is released from platelets at the
cape of bacteria from a focus of infection, site of bleeding, where it constricts small
such as an abscess, and is more likely to blood vessels, reducing blood loss. In
occur in people with an immunodefici- the digestive tract, it inhibits gastric
ency disorder, cancer, or diabetes mellitus; secretion and stimulates smooth mus-
in those who take immunosuppressant cle of the intestine. In the brain, where
drugs; and in drug addicts who inject. it acts as a neurotransmitter, levels are
reduced in people who are depressed;
Symptoms include a fever, chills, rapid certain antidepressants raise the level.
breathing, headache, and clouding of Serotonin agonists are used to block its
consciousness. The sufferer may go into effects in acute migraine attacks.
life-threatening septic shock.
serotonin agonists A group of drugs,
Glucose and/or saline are given by also known as 5HT1 agonists, used to
intravenous infusion, and antibiotics treat acute attacks of migraine. They
by injection or infusion. Surgery may be work on the same receptors in the brain
necessary to remove the original infec- as 5 hydroxytryptamine (5HT), a neuro-
tion. If treatment is given before septic transmitter and vasodilator. Common
shock develops, the outlook is good. serotonin agonists include naratriptan
septic arthritis A type of arthritis and sumatriptan. These drugs can cause
caused by a bacterial infection entering chest pain, particularly in people with
a joint via an open wound. Symptoms heart disease. They should be used with
of septic arthritis appear suddenly and caution in those at increased risk of cor-
may include swelling, tenderness, and onary artery disease. Other side effects
fever. If pus builds up, the joint may be include flushing, tingling, and nausea.
permanently damaged.
serotonin antagonists A group of drugs
Fluid is taken from the joint and is used to treat the nausea and vomiting
analysed to determine the presence of caused by radiotherapy and anticancer
infection (see aspiration), and pus may drugs. They are also used to control
be drained to help relieve pain. Initially, nausea and vomiting following surgery.
treatment is with intravenous antibiotic Common serotonin antagonists include
drugs, followed by oral antibiotics for granisetron and ondansetron.
several weeks or months after that.
septic shock A life-threatening condi- sertraline A selective serotonin reuptake
tion in which there is tissue damage inhibitor drug used in the treatment of
and a dramatic drop in blood pressure depression (see antidepressants).
as a result of septicaemia.
septum A thin dividing wall within or serum The clear fluid that separates from
between parts of the body. blood when it clots. It contains salts, glu-
sequela A condition that results from or cose, and proteins, including antibodies.
follows a disease, disorder, or injury. The Serum from the blood of a person who
term is usually used in plural (sequelae) has been infected with a microorganism
to refer to the complications of a disease. usually contains antibodies that can pro-
sequestration A portion of diseased or tect other people from that organism if
dead tissue separated from, or joined ab- injected into them. Such a preparation
normally to, surrounding healthy tissue. is called an antiserum; its use forms the
serology A branch of laboratory medicine basis of passive immunization.
concerned with analysis of blood serum.
Applications of serological techniques serum sickness A type of hypersensi-
include the diagnosis of infectious dis- tivity reaction that may develop about
eases by the identification of antibodies, 10 days after injection with an anti-
the development of antiserum prepara- serum of animal origin or after taking
tions for passive immunization, and the certain drugs such as penicillins. Symp-
determination of blood groups in pater- toms may include an itchy rash, joint
nity testing and forensic investigations. pain, fever, and enlarged lymph nodes.
In severe cases, a state similar to shock

505

SEX SEXUAL CHARACTERISTICS

develops. Symptoms usually clear up form. In the absence of these hormones,

in a few days; antihistamine drugs may a female reproductive tract develops. At

hasten recovery. In severe cases, a puberty, another surge of hormones pro-

corticosteroid drug may be prescribed. duces secondary sexual characteristics.

sex Another term for gender and a com- Chromosomal abnormalities or hor-

monly used term for sexual intercourse. monal defects can lead to ambiguous

sex change Radical surgical procedures, sex (see genitalia, ambiguous), although

usually combined with hormone therapy, true hermaphroditism is rare.

that alter a person’s anatomical gender. sex hormones Hormones that control

Sex-change operations are performed on the development of primary and secon-

transsexuals (see transsexualism) and dary sexual characteristics and that

on infants whose external sex organs regulate sex-related functions, such as

are neither completely male nor female the menstrual cycle. There are 3 main

(see genitalia, ambiguous). types: androgen hormones, oestrogen

sex chromosomes A pair of chromo- hormones, and progesterone hormone.

somes that determines an individual’s sex-linked inheritance The passing

sex. All human cells (except egg or on to the next generation of a trait or

sperm cells) contain a pair of sex chro- disorder determined by the sex chromo-

mosomes, together with 22 other pairs somes, or by the genes carried on them.

of chromosomes called autosomes. In Disorders caused by an abnormal num-

women, there are 2 similar sex chromo- ber of sex chromosomes include Turner’s

somes called X chromosomes. Men have syndrome and Klinefelter’s syndrome.

1 X and 1 Y chromosome. The genes on Most other sex-linked traits or disorders

the Y chromosome are concerned solely are caused by recessive genes on the

with sex determination; their presence X chromosome (see genetic disorders).

ensures a male, their absence a female. sex therapy Counselling for and treat-

The X chromosome carries genes vital ment of sexual difficulties not due to a

to general development and functioning. physical cause. It may involve changing

the attitude of the partners towards sex,

SEX CHROMOSOMES increasing their understanding of sexual

X chromosome Y chromosome needs, and teaching techniques, such as
the sensate-focus technique or pelvic floor

exercises, for specific problems. Sex ther-

apy is particularly successful in treating

vaginismus, premature ejaculation (see

ejaculation, disorders of), lack of orgasm

(see orgasm, lack of), and impotence.

sexual abuse The subjection of a per-

S son to sexual activity that has caused or
is likely to cause physical or psychologi-

cal harm. (See also child abuse; rape.)

sexual characteristics, secondary

Physical features appearing at puberty

that indicate the onset of adult reproduc-

tive life. In girls, breast enlargement is

the first sign. Shortly afterwards, pubic

and underarm hair appears, and body fat

increases around the hips, stomach, and

sex determination The factors that thighs to produce the female body shape.

determine biological sex. The underlying In boys, the first sign is enlargement of

determinants are the sex chromosomes the testes, followed by thinning of the

which cause the differential development scrotal skin and enlargement of the

of the gonads in the embryo. In males, penis. Pubic, facial, axillary, and other

the testes then produce hormones that body hair appears, the voice deepens,

cause the male reproductive organs to and muscle bulk and bone size increase.

506

SEXUAL DESIRE, INHIBITED SHOCK

sexual desire, inhibited Lack of sexual shellfish poisoning See food poisoning. S
desire or of the ability to become physi- shell shock See post-traumatic stress
cally aroused during sexual activity.
disorder.
sexual deviation See deviation, sexual. shigellosis An acute infection of the
sexual dysfunction See psychosexual
intestine by bacteria of the genus SHI-
dysfunction. GELLA. The source of the infection is the
sexual intercourse A term sometimes faeces of infected people; the bacteria
are spread by poor hygiene. Endemic
used to describe a variety of sexual activ- in some countries, shigellosis occurs in
ities, but which specifically refers to the isolated outbreaks in the UK.
insertion of the penis into the vagina.
sexuality A term describing the capacity The disease usually starts suddenly,
for sexual feelings and behaviour, or an with diarrhoea, abdominal pain, nausea,
individual’s sexual orientation or prefer- vomiting, generalized aches, and fever.
ence. Heterosexuality is sexuality directed Persistent diarrhoea may cause dehydra-
towards the anatomically opposite sex; tion, especially in babies and the elderly.
homosexuality is attraction to the same Occasionally, toxaemia develops.
sex; and bisexuality is attraction to both
sexes. (See also gender identity.) Shigellosis usually subsides after a
sexually transmitted infections (STIs) week or so, but hospital treatment may
Infections transmitted primarily, but not be needed for severe cases. Dehydra-
exclusively, by sexual intercourse. Com- tion is treated by rehydration therapy.
mon STIs include chlamydial infections, Antibiotics may be given.
genital herpes, pubic lice, genital warts, shingles See herpes zoster.
trichomoniasis, syphilis, gonorrhoea, and shin splints Pain in the front and sides
HIV infection. Antibiotics can be used to of the lower leg that develops or wors-
treat most bacterial STIs. Confidential ens during exercise. There may also be
tracing and treatment of an affected per- tenderness and oedema in the affected
son’s partners is an essential part of the area. Shin splints is a common problem
management of STIs (see contact tracing). in runners. It may be caused by various
Practising safer sex can help prevent STIs. disorders, such as compartment syn-
sexual problems Any difficulty associat- drome, tendinitis, myositis, or periostitis.
ed with sexual performance or behaviour.
Sexual problems are often psychological In most cases, the pain disappears
in origin (see psychosexual dysfunction). after 1 or 2 weeks of rest. However, if it
Sex therapy may help such problems. is severe or recurrent, a course of non-
Some sexual problems are due to physi- steroidal anti-inflammatory drugs or
cal disease, such as a disorder affecting corticosteroids may be needed. Rarely,
blood flow or a hormonal dysfunction. surgery is performed to alleviate exces-
A disorder of the genitals may result in sive pressure in a muscle. Some people
pain during intercourse (see intercourse, benefit from physiotherapy.
painful). Such problems are addressed shivering Involuntary trembling of the
by treating the cause, where possible. entire body that is caused by rapid
Sézary syndrome A rare condition in contraction and relaxation of muscles.
which there is an abnormal overgrowth of Shivering is the body’s normal auto-
lymphocytes in the skin, liver, spleen, and matic response to cold; contraction of
lymph nodes. It mainly affects middle- muscles generates heat. Shivering also
aged and elderly people. The first occurs in fever.
symptom is the appearance of red, scaly shock A dangerous reduction of blood
patches on the skin that spread to form flow throughout the body tissues, which
an itchy, flaking rash. There may also be may occur with severe injury or illness.
accumulation of fluid under the skin, Shock in this sense is physiological shock,
baldness, and distorted nail growth. as distinct from the mental distress that
Sézary syndrome is sometimes associ- may follow a traumatic experience.
ated with leukaemia. Treatment includes
anticancer drugs and radiotherapy. In most cases, reduced blood pressure
is a major factor in causing shock and is
one of its main features. Shock may de-
velop in any situation in which blood

507

SHOCK, ELECTRIC SHOULDER–HAND SYNDROME

volume is reduced, blood vessels are An affected child’s growth rate is moni-

abnormally widened, the heart’s action is tored by regular measurement of height.

weak, blood flow is obstructed, or there X-rays and blood tests may help identify

is a combination of these factors. Caus- an underlying cause, which will then be

es include severe bleeding or burns, treated. Growth hormone is given for hor-

persistent vomiting or diarrhoea, myo- mone deficiency, and also to treat short

cardial infarction, pulmonary embolism, stature due to disorders such as Turner’s

peritonitis, and some types of poisoning. syndrome. (See also growth, childhood.)

Symptoms of shock include rapid, shoulder The area of the body where the

shallow breathing; cold, clammy skin; arm attaches to the trunk.Three bones

rapid, weak pulse; dizziness; weakness; meet here: the scapula, clavicle, and

and fainting. Untreated, shock can lead humerus. The ball-and-socket joint at the

to collapse, coma, and death. shoulder has a wide range of movement.

Emergency treatment is required. This Common injuries include dislocation

involves an intravenous infusion of fluid, (see shoulder, dislocation of) and frac-

a blood transfusion, oxygen therapy, tures of the clavicle or upper humerus.

and, if necessary, morphine or similar The shoulder may be affected by any

powerful analgesics. Further treatment joint disorder, which in severe cases may

depends on the underlying cause. (See lead to frozen shoulder. Inflammation of

also anaphylactic shock; septic shock; a tendon or a bursa around a shoulder

shock, electric; toxic shock syndrome.) joint can cause painful arc syndrome.

shock, electric The sensation caused by shoulderblade The common name for

an electric current passing through the the scapula.

body, and its effects. A current of suffi- shoulder, dislocation of Displacement

cient size and duration can cause loss of of the head of the humerus out of the

consciousness, cardiac arrest, respiratory shoulder joint. The main symptom is

arrest, burns, and tissue damage. (See pain in the shoulder and upper arm, made

also electrical injury.) worse by movement. A forward disloca-

shock therapy See ECT. tion often produces obvious deformity;

shortsightedness See myopia. a backward dislocation usually does not.

short sight, operations for See LASIK; Diagnosis is by X-rays. The head of

photorefractive keratectomy; keratotomy, the humerus is repositioned in the joint

radial. socket. The shoulder is then immobilized

short stature A height significantly be- in a sling for about 3 weeks.

low the normal range for a person’s age. Complications of shoulder dislocation

Short stature in children is often due to include damage to nerves, causing tem-

hereditary factors or slow bone growth. porary weakness and numbness in the

In most cases, growth eventually speeds shoulder; damage to an artery in the

S up, resulting in normal adult height. Less upper arm, causing pain and discolor-
commonly, it is due to a specific disorder ation of the arm and hand; and damage

such as bone disease (as in untreated to muscles that support the shoulder.

rickets or achondroplasia) or certain hor- shoulder–hand syndrome Pain and

monal disorders such as growth hormone stiffness affecting one shoulder and the

deficiency and hypothyroidism. Emotional hand on the same side; the hand may

deprivation, chronic malnutrition and also become hot, sweaty, and swollen.

malabsorption can also limit growth. Cer- Arm muscles may waste through lack of

tain chromosomal disorders cause short use (see Sudeck’s atrophy). The cause of

stature; stunting occurs in Down’s syn- shoulder–hand syndrome is unknown,

drome, and the pubertal growth spurt is but it may occur as a complication of

absent in Turner’s syndrome. Other myocardial infarction, stroke, herpes

causes of restricted growth in children zoster, or shoulder injury. Recovery usu-

include prolonged use of corticosteroids ally occurs in about 2 years. This period

and anticancer drugs. Severe untreated may be shortened by physiotherapy and

respiratory disease or congenital heart corticosteroid drugs. In rare cases, a cer-

disease can also cause short stature. vical sympathectomy is performed.

508

SHUNT SIDS

shunt An abnormal or surgically created swelling of the hands and feet. Chronic S
passage between two normally uncon- haemolytic anaemia causes fatigue,
nected body parts. headaches, shortness of breath on exer-
tion, pallor, and jaundice. Sickle cell
Shy–Drager syndrome A rare degener- crises start suddenly; they are sometimes
ative disorder of unknown cause that brought on by an infection, cold wea-
progressively damages the autonomic ther, or dehydration, but may also occur
nervous system. It begins gradually at for no apparent reason. The sufferer may
age 60–70 and is more common in men. experience pains (especially in the
Symptoms include dizziness and fainting bones), blood in the urine (from kidney
due to postural hypotension, urinary in- damage) or damage to the lungs or intes-
continence, impotence, reduced ability to tines. If the brain is affected, seizures, a
sweat, and parkinsonism. The condition stroke, or unconsciousness may result.
eventually leads to disability, and some-
times premature death. There is no cure In some affected children, the spleen
or means of slowing degeneration, but enlarges and traps red cells at a particu-
many symptoms are relieved by drugs. larly high rate, causing a life-threatening
form of anaemia. After adolescence, the
SIADH The abbreviation for syndrome of spleen usually stops functioning, increas-
inappropriate antidiuretic hormone (se- ing the risk of infection in those affected.
cretion), associated with certain lung or
brain disorders and some types of cancer. Diagnosis is made from examination of
a blood smear and electrophoresis. Sup-
Siamese twins See twins, conjoined. portive treatment may include folic acid
sibling rivalry A term that describes supplements, and penicillin and immu-
nization to protect against infection.
the intense competition that sometimes Life-threatening crises are treated with
occurs between siblings. intravenous infusions of fluids, antibiotics,
sibutramine A centrally acting appetite oxygen therapy, and analgesic drugs. If
suppressant drug used to treat obesity the crisis still does not respond, an
in people who have not responded to exchange blood transfusion may be per-
other methods of weight loss, such as formed. This may be done regularly for
dieting. Common side effects include people who suffer frequent severe crises.
constipation, dry mouth, and hyperten- sick sinus syndrome Abnormal func-
sion. People taking this drug should tion of the heart’s sinoatrial node that
have regular follow-ups and have their leads to episodes of bradycardia (slow
blood pressure and pulse monitored. heart-rate), alternating bradycardia and
sick building syndrome A collection tachycardia (fast heart-rate), or very short
of symptoms reported by some workers episodes of cardiac arrest. The cause is
in office buildings. Symptoms include usually coronary artery disease, but may
loss of energy, headaches, and dry, itch- be a cardiomyopathy. Symptoms may
ing eyes, nose, and throat. The cause is include lightheadedness, fainting, and
unknown, but various factors are invol- palpitations. The diagnosis is confirmed
ved, including air conditioning, passive by a 24-hour ECG recording. Treatment
smoking, lack of natural ventilation and is usually by antiarrhythmic drugs and
light, and psychological factors. the fitting of an artificial pacemaker.
sickle cell anaemia An inherited blood side effect A reaction or consequence of
disease in which the red blood cells con- medication or therapy that is additional
tain haemoglobin S, an abnormal type of to the desired effect. The term usually
haemoglobin. This crystallizes in the cap- refers to an unwanted or adverse effect,
illaries, making red cells sickle-shaped usually following a normal dose, rather
and fragile, and leading to haemolytic than the toxic effects, of a drug overdose.
anaemia. The abnormal cells are unable siderosis Any of a variety of conditions
to pass easily through tiny blood vessels. in which there is too much iron in the
The blood supply to organs is blocked body. (See also haemosiderosis.)
intermittently, causing sickle cell crises. SIDS An abbreviation for sudden infant
The disease affects mainly black people. death syndrome.

Symptoms usually appear after age 6
months, often beginning with painful

509

SIEVERT SINUS, FACIAL

sievert A unit for measuring doses of ulcers, and pressure sores. Side effects
ionizing radiation. (See radiation units). may include permanent grey skin dis-
coloration, rashes, or itching.
sight See vision. simvastatin A lipid-lowering drug that
sight, partial Loss of vision short of acts on the liver enzymes that produce
cholesterol. It may cause bowel upsets,
total blindness. Partial sight may involve headaches, and muscle pains.
loss of visual acuity and/or visual field. sinew A nonmedical term for a tendon.
sigmoid colon The S-shaped part of singer’s nodes Small, greyish-white
the colon, in the lower abdomen, extend- nodules that develop on the vocal cords
ing from the brim of the pelvis, usually as the result of constant voice strain. In
down to the 3rd segment of the sacrum. acute cases, treatment consists of rest-
It is connected to the descending colon ing the voice. In chronic cases, surgical
above, and the rectum below. removal of the nodes may be necessary.
sigmoidoscopy A form of endoscopy in sinoatrial node The natural pacemaker
which a viewing instrument is inserted of the heart. The sinoatrial node consists
through the anus to examine the rectum of a cluster of specialized muscle cells
and sigmoid colon. in the right atrial wall. These cells regu-
sign An objective indication of a dis- larly emit electrical impulses, which
ease or disorder (for example, jaundice) initiate the contractions of the heart.
that is observed or detected by a doctor, sinus A cavity in a bone, in particular
as opposed to a symptom (for example, one of the air-filled spaces in the bones
pain), which is noticed by the patient. surrounding the nose (see sinus, facial).
sildenafil Commonly known by its brand
name Viagra, a drug used in the treat- The term sinus also refers to any wide
ment of impotence. Because of the risk channel that contains blood, or to an
of potentially serious side effects in cer- abnormal, often infected, tract.
tain people, the drug must only be used sinus bradycardia A slow, but regular
on medical advice. heart-rate (less than 60 beats per min-
silicone A long-chain, carbon-containing ute) caused by reduced electrical activity
compound of silicon and oxygen. Synth- in the sinoatrial node. Sinus bradycardia
etic silicones are sometimes used as is normal in athletes, but in others it may
implants in cosmetic surgery. be caused by hypothyroidism, a myo-
silicosis A lung disease caused by the cardial infarction, or by drugs such as
inhalation of dusts containing silica. beta-blockers or digoxin.
(See also pneumoconiosis.) sinus, facial Any of the air-filled cavi-
silver sulfadiazine An antibacterial ties in the bones surrounding the nose.
drug applied as a cream to prevent infec- These include 2 frontal sinuses in the
tion after skin grafts or in burns, leg

S SINUS, FACIAL
Frontal
sinus Ethmoid
sinuses

Ethmoid Frontal
sinuses sinus

Maxillary
sinus

Sphenoid
sinus

Maxillary
sinus

FRONT VIEW SIDE VIEW

510

SINUSITIS SKIN

lower forehead; 2 ethmoidal sinuses be- SKELETON Parietal bone
tween the eyes; 2 maxillary sinuses in Temporal bone
the cheekbones; and the sphenoidal Frontal bone Occipital bone
sinuses in the skull behind the nose. Zygomatic arch
Mucus drains from each sinus along a Mandible
channel that opens into the nose. Infec- Scapula Clavicle
tion of a sinus causes sinusitis. Sternum Rib
sinusitis Inflammation of the membrane
lining the facial sinuses caused by infec- Humerus Vertebral
tion, usually spread from the nose. The column
maxillary and the ethmoidal sinuses are Ulna Ilium
most commonly affected. Radius
Pubis
Sinusitis may cause a feeling of fullness Ischium
in the affected area, fever, a stuffy nose,
and loss of the sense of smell. A com- Femur Carpals
mon complication is the formation of Patella
pus in the affected sinuses, causing Metacarpals
pain and nasal discharge. Phalanges

Treatment of sinusitis is is usually Tibia
with antibiotics and a decongestant.
Steam inhalations may also be helpful. If Fibula
sinusitis persists despite treatment,
surgical drainage of the affected sinuses Tarsals Calcaneus
may be performed.
sinus tachycardia A fast, but regular, Phalanges
heart-rate (more than 100 beats per
minute) caused by increased electrical Metatarsals
activity in the sinoatrial node. Such a
heartbeat is normal during sudden movement by providing a strong, stable S
stressful moments or exercise. Persis- but mobile framework on which mus-
tent sinus tachycardia at rest may be cles can act. The skeleton also supports
caused by fever or hyperthyroidism. and protects internal body organs.
situs inversus An unusual condition in skin The outermost covering of body tis-
which the internal organs are situated sue, which protects internal organs from
in the mirror image of their normal posi- the environment. Skin has 2 layers: the
tions. No treatment is needed provided outer epidermis, and the inner dermis.
all the organs are functioning normally.
Sjögren’s syndrome A condition in The outermost epidermis is composed
which the eyes and mouth are excessively of dead cells and the protein keratin. As
dry. The nasal cavity, throat, and vagina these dead cells are worn away, they are
may also be affected. The syndrome replaced by new ones from the inner epi-
tends to occur with certain autoimmune dermis. Some epidermal cells produce
disorders, such as rheumatoid arthritis the pigment melanin, which protects the
and systemic lupus erythematosus. Most body from ultraviolet light in sunlight.
sufferers are middle-aged women.
skeleton The framework of bones that The dermis is composed of connective
gives the body shape and provides tissue interspersed with hair follicles,
attachment points for the muscles and
underlying soft tissues of the body. The
average human adult skeleton has 213
bones (counting each of the 9 fused ver-
tebrae of the sacrum and coccyx as
individual bones) joined with ligaments
and tendons at points called joints. The
skeleton plays an indispensable role in

511

SKIN ALLERGY SKIN GRAFT
Venule
SKIN
Sweat pore
Sweat duct Hair shaft
Epidermis Scaly upper layer
Sebaceous
Dermis gland

Subcutaneous Nerve ending
fat Arrector pili
muscle

Blood vessel

Hair follicle
Hair bulb
Nerve
Sweat gland

sweat glands, sebaceous glands, blood skin, disorders of the The skin is vul-

and lymph vessels, and sensory receptors nerable to various disorders, including

for pressure, temperature, and pain. birthmarks and other naevi; infections

skin allergy Irritation of the skin follow- that may be viral (such as cold sores and

ing contact with a specific substance that warts), bacterial (for example, cellulitis),

provokes an inappropriate or exagger- or fungal (such as tinea, which causes

ated reaction from the immune system. athlete’s foot); rashes due to vitamin

There are 2 main types of allergic skin deficiency or the side effects of drugs;

reaction. In contact allergic dermatitis, and tumours, both noncancerous and

red, itchy patches develop a few hours cancerous. Acne is common in adoles-

to 2 days after contact with the allergen. cents and is partly related to the action

In contact urticaria, red, raised areas of androgen hormones. Inflammation of

appear a few minutes after skin contact. the skin occurs in dermatitis, eczema,

In some cases, skin tests are needed, to and skin allergy. The skin is also vulner-

S identify the allergen, for contact with it to able to injuries such as burns, cuts, and
be minimized. (See also atopic eczema.) bites (see bites, animal; insect bites).

skin biopsy Removal of a portion of skin skin flap A surgical technique in which

for laboratory analysis in order to diag- a section of skin and underlying tissue,

nose a skin disorder. sometimes including muscle, is moved

skin cancer A malignant tumour in the to cover an area from which skin and tis-

skin. Basal cell carcinoma, squamous cell sue have been lost or damaged by injury,

carcinoma, and malignant melanoma are disease, or surgery. Unlike a skin graft, a

common forms related to long-term skin flap retains its blood supply, either

exposure to sunlight. Bowen’s disease, a by remaining attached to the donor site

rare disorder that can become cancer- or through reattachment to blood vessels

ous, may also be related to sun exposure. at the recipient site by microsurgery, so

Less common types include Paget’s dis- skin flaps adhere well even where there

ease of the nipple and mycosis fungoides. is extensive loss of deep tissue.

Kaposi’s sarcoma is a type usually found skin graft A technique used to repair

in people with AIDS. Most skin cancers areas of lost or damaged skin that are

can be cured if treated early. too large to heal naturally, that are slow

512

SKIN PATCH SLEEP S

to heal, or that would leave tethering or skin tests Procedures for determining the
unsightly scars. A skin graft is often body’s reaction to various substances by
used in the treatment of burns or some- injecting a small quantity of the sub-
times for nonhealing ulcers. A piece of stance under the skin or by applying it
healthy skin is detached from one part to the skin (usually on patches). Patch
of the body and transferred to the tests are used in the diagnosis of contact
affected area. New skin cells grow from allergic dermatitis. They can also be used
the graft and cover the damaged area. to test immunity to certain infectious
In a meshed graft, donor skin is diseases (such as in the tuberculin test).
removed and made into a mesh by cut-
ting. The mesh is stretched to fit the skin tumours A growth on or in the skin
recipient site; new skin cells grow to fill that may be cancerous (see skin cancer)
the spaces in the mesh. In a pinch graft, or noncancerous. Keratoses and squa-
multiple small areas of skin are pinched mous papillomas are common types of
up and removed from the donor site. noncancerous tumour; other types inc-
Placed on the recipient site, they gradu- lude sebaceous cysts, cutaneous horns,
ally expand to form a new sheet of keratoacanthomas, and haemangiomas.
healthy skin. (See also skin flap.)
skull The bony skeleton of the head,
SKIN GRAFT which rests on the 1st cervical vertebra.
The skull protects the brain, houses the
Healthy special sense organs, provides points of
skin attachment for muscles, and forms part
of the respiratory and digestive tracts .
Meshed The 8 bones of the cranium encase the
graft brain. The skull’s facial skeleton includes
the nasal and cheek bones, maxilla, and
Recipient mandible. All except the mandible are
site fixed together by immovable joints.

MESHED SKIN GRAFT skull, fracture of A break in 1 or more of
Pinch the skull bones caused by a head injury.
graft In most skull fractures, the broken bones
are not displaced and there are no com-
Recipient plications. Severe injury may result in
site bone fragments rupturing blood vessels
in the meninges, or, more rarely, tearing
PINCH SKIN GRAFT the meninges, leading to brain damage.
A fracture without complications usually
skin patch See transdermal patch. heals by itself; damage to brain struc-
skin peeling, chemical A cosmetic tures often requires neurosurgery.

operation in which the outer layers of skull X-ray A technique for providing
the skin are peeled away by the applica- images of the skull. X-rays of the skull
tion of a caustic paste in order to remove are usually taken after a head injury to
freckles, acne scars, delicate wrinkles, or look for a fracture or foreign body, or to
other skin blemishes. evaluate disorders that affect the skull.
skin tag A harmless, small, brown or
flesh-coloured flap of skin that may slapped cheek syndrome An alterna-
appear spontaneously or as a result of tive name for fifth disease, an infection
poor healing of a wound. in children caused by parvovirus in
which the cheeks become reddened.

SLE The abbreviation for the disorder
systemic lupus erythematosus.

sleep The natural state of lowered con-
sciousness and reduced metabolism.
There are 2 types of sleep: REM (rapid
eye movement) and NREM (nonrapid eye
movement) sleep, which alternate in
cycles. NREM sleep consists of 4 stages

513

SLEEP APNOEA SLING

of progressively greater “depth”, with sleep deprivation Insufficient sleep. Irri-

slowing of brain activity. In REM sleep, tability and a shortened attention span

the brain becomes more active; the may occur after a short night’s sleep.

eyes move rapidly and dreaming occurs. Longer periods without sleep leave a

Sleep is a fundamental human need, as person increasingly unable to concen-

shown by the effects of sleep deprivation, trate or perform normal tasks. Three or

although its purpose is not understood more sleepless nights may lead to hallu-

in detail. The need for sleep varies from cinations and, in some cases, to paranoia.

person to person and decreases with age. sleeping drugs A group of drugs used

Sleep disorders include difficulty in to treat insomnia. They include benzodi-

falling or remaining asleep (see insom- azepines, antihistamines, antidepressants,

nia); difficulty in staying awake (see and chloral hydrate. Sleeping drugs may

narcolepsy); disruption of sleep by jet- cause drowsiness and impaired concen-

lag and bed-wetting, night terrors, or tration on waking. Long-term use may

sleepwalking. (See also sleep apnoea.) induce tolerance and dependence.

sleep apnoea A disorder in which there sleeping sickness A serious infectious

are episodes of temporary cessation of disease of tropical Africa caused by the

breathing (lasting 10 seconds or longer) protozoan parasite TRYPANOSOMA BRUCEI,

during sleep. which is transmitted to humans by the

People with sleep apnoea may not be bites of tsetse flies.

aware of any problem during the night, One form of the disease, which occurs

but they may be sleepy during the day, in West and Central Africa, takes a slow

with poor memory and concentration. course, with bouts of fever and lymph

Severe sleep apnoea is potentially seri- node enlargement. After months or years,

ous and may lead to hypertension, heart spread to the brain occurs, causing head-

failure, myocardial infarction, or stroke. aches, confusion, and, eventually, severe

Obstructive sleep apnoea is the most lassitude. Without treatment, coma and

common type and may affect anyone, death follow. The other, East African,

but more often middle-aged men, espe- form runs a faster course. Fever devel-

cially those who are overweight. The ops after a few weeks of infection, and

most common cause is over-relaxation effects on the heart may be fatal before

of the muscles of the soft palate in the the disease has spread to the brain.

pharynx, which obstructs the passage of Drugs can effect a cure, but there may

air. Obstruction may also be caused by be residual brain damage if the infec-

enlarged tonsils or adenoids. The obstruc- tion has already spread to the brain.

tion causes snoring. If complete blockage sleep paralysis The sensation of being

occurs, breathing stops. This triggers unable to move at the moment of going

the brain to restart breathing, and the to sleep or when waking up, usually

S person may gasp and wake briefly. lasting only a few seconds. It may be
In central sleep apnoea, breathing stops accompanied by hallucinations. Sleep

because the chest and diaphragm mus- paralysis most often occurs in people

cles temporarily cease to work, probably with narcolepsy. (See also cataplexy.)

due to a disturbance in the brain’s con- sleep terror See night terror.

trol of breathing. Causes include paralysis sleepwalking Walking while asleep.

of the diaphragm and disorders of the Sleepwalking is usually calm and aim-

brainstem. Snoring is not a main feature. less, although it is sometimes more

People who are overweight may find frantic when it occurs with night terror.

losing weight helps. Alcohol and sleep- Some people regularly sleepwalk. Sleep-

ing drugs aggravate sleep apnoea. In walking in children is not normally a

one treatment, air from a compressor is cause for concern and tends to disap-

forced into the airway via a mask worn pear with age. In adults, it may be related

over the nose. Night-time artificial ven- to anxiety or the use of sleeping drugs.

tilation may be needed. Tonsillectomy, slimming See weight reduction.

adenoidectomy, or surgery to shorten or sling A triangular bandage used to

stiffen the soft palate may be performed. immobilize, support, or elevate an arm.

514

SLIPPED DISC SNAILS AND DISEASE

SLING The injured arm in which thickening of the mucous mem-
may be supported brane obscures olfactory nerve endings;
atrophic rhinitis, in which the nerves
horizontally or held waste away; head injury that tears the
nerves; or a tumour of the meninges or
Injured elevated, depend- nasopharynx. The perception of illusory,
arm ing on the injury. unpleasant odours may be a feature of
slipped disc See depression, schizophrenia, some forms
of epilepsy, or alcohol withdrawal.
disc prolapse. smelling salts A preparation of ammo-
nia that was used in the past to revive a
slipped femoral person who felt faint.
smoking Smoking tobacco in the form of
epiphysis See cigarettes or cigars, or in pipes. Over
100,000 deaths per year in the UK are
femoral epiphysis, attributed to smoking. The main harm-
ful effects of smoking are lung cancer,
slipped. bronchitis, emphysema, coronary artery
disease, and peripheral vascular disease.
slit-lamp An illu- Smoking also increases the risk of
mouth cancer, lip cancer, and throat
minated type of cancer (see pharynx, cancer of).

microscope that is Smoking is extremely harmful during
pregnancy. Babies of women who
ELEVATION SLING used to examine smoke are smaller and are less likely to
the internal struc- survive than those of nonsmoking
mothers. Children with parents who
tures of the front smoke are more likely to suffer from
asthma or other respiratory diseases.
part of the eye and of the retina at the
There is also evidence that passive
back. (See also eye, examination of.) smokers are at increased risk of tobacco-
related disorders and also suffer dis-
slough Dead tissue that has been shed comfort in the form of coughing,
wheezing, and sore eyes.
from its original site; for example, loss
Tobacco contains many toxic chemi-
of dead skin cells from the skin’s surface. cals. Nicotine is the substance that
causes addiction to tobacco. It acts as a
slow virus diseases A group of dis- tranquillizer but also stimulates the
release of adrenaline into the blood-
eases of the central nervous system that stream. This can raise blood pressure.
Tar in tobacco produces chronic irrita-
occur many months or even years after tion of the respiratory system and is
thought to be a major cause of lung
infection with a virus. They cause gradual cancer. Carbon monoxide passes from
the lungs into the bloodstream, where
widespread destruction of nerve tissue, it easily combines with haemoglobin in
red blood cells, interfering with oxy-
with progressive loss of brain function genation of tissues. In the long term,
persistently high levels of carbon
and a fatal outcome. Examples include monoxide in the blood cause hardening
of the arteries, which greatly increases
Creutzfeldt–Jakob disease and kuru. the risk of coronary thrombosis.
snails and disease Snails act as host to
small cell carcinoma One form of various types of fluke that infest humans,
such as liver flukes.
lung cancer.

smallpox A highly infectious viral dis-

ease that was declared eradicated in

1980 after a global vaccination campaign.

smear A specimen for microscopic

examination prepared by spreading a

thin film of cells on to a glass slide.

smegma An accumulation of sebaceous S

gland secretions under the foreskin in an

uncircumcised male, usually as a result

of poor hygiene. Fungal or bacterial in-

fection of smegma may cause balanitis.

smell One of the 5 senses. In the nose,

hair-like projections from smell receptor

cells lie in the mucous membrane. When

the receptors are stimulated by certain

molecules, they transmit impulses along

the olfactory nerves to the smell centres

in the limbic system and frontal lobes of

the brain, where smell is perceived.

Possible causes of loss of the sense

of smell include inflammation of the

nasal membrane, as in a common cold;

cigarette smoking; hypertrophic rhinitis,

515

SNAKE BITES SODIUM CROMOGLICATE

snake bites Most snake bites are by non- are encouraged to improve their ability to

venomous species. Venomous snakes are communicate. This is an important part

found mainly in the tropics; the only of rehabilitation for people with mental

species native to the UK is the adder. handicap or those with chronic psych-

The effects of a venomous bite depend ological disorders, such as schizophrenia.

on the species and size of the snake, Role-playing is a commonly used tech-

the amount of venom injected, and the nique in which various social situations

age and health of the victim. A bite from are simulated in order to improve the

an adder or other viper typically causes individual’s confidence and performance.

immediate pain and swelling at the site, sociopathy An outdated term for anti-

followed by dizziness and nausea, a social personality disorder.

drop in blood pressure, an increase in sodium A mineral that helps to regulate

heart-rate, and internal bleeding. the body’s water balance and maintain

Antibiotic drugs and tetanus antitoxin normal heart rhythm and is involved in

injections are given for all bites to pre- conduction of nerve impulses and con-

vent infection and tetanus. An injection traction of muscles. The level of sodium

of antivenom is also given for a ven- in the blood is controlled by the kidneys,

omous bite. With prompt treatment, which eliminate any excess in the urine.

most victims recover completely. Almost all foods contain sodium natu-

sneezing The involuntary expulsion of air rally or as an ingredient added during

through the nose and mouth as a result processing or cooking. Consequently,

of irritation of the upper respiratory tract. deficiency is rare and is usually the

This may be due to the common cold, result of excessive loss of the mineral

allergic rhinitis, the presence of mucus, through persistent diarrhoea or vomiting,

or inhaling an irritant substance. or profuse sweating. Symptoms include

Snellen chart A method of measuring weakness, dizziness, and muscle cramps.

visual acuity used during vision tests. In severe cases, there may be a drop in

snoring Noisy breathing through the blood pressure, leading to confusion,

open mouth during sleep, produced by fainting, and palpitations. Treatment is

vibrations of the soft palate. Snoring is with supplements. In hot climates, sodium

often caused by a condition that hinders supplements may help to prevent heat

breathing through the nose, such as a disorders by compensating for sodium

cold, allergic rhinitis, or enlarged ade- lost through heavy sweating.

noids. Snoring is more common when Excessive sodium intake is thought to

sleeping on the back. If the underlying be a contributory factor in hypertension.

cause can be treated, snoring may stop. Another adverse effect is fluid reten-

Snoring is also a feature of sleep apnoea. tion, which, in severe cases, may cause

snow-blindness A common name for dizziness and swelling of the legs.

S actinic keratopathy. sodium aurothiomalate A preparation

snuff A preparation of powdered tob- of gold that is given by injection.

acco (often with other substances) for sodium bicarbonate An over-the-

inhalation. Snuff is addictive because it counter antacid drug used to relieve

contains nicotine; it also irritates the indigestion, heartburn, and pain caused

nasal lining and increases the risk of by a peptic ulcer. It often causes belching

cancer of the nose and throat. and abdominal discomfort. Long-term

snuffles A general term for nasal obstruc- use may cause swollen ankles, muscle

tion, especially in infants suffering from cramps, tiredness, and nausea.

an upper respiratory tract infection. sodium cromoglicate A drug given by

social and communication disorders inhaler to control mild asthma in chil-

A collective term for disorders such as dren and allergic or exercise-induced

Asperger’s syndrome and autism, which asthma in adults; as a nasal spray to

begin in childhood. Problems tend to treat allergic rhinitis; in eye-drops for

persist throughout life. allergic conjunctivitis; and orally for food

social skills training A form of behav- allergy. Side effects include coughing

iour modification in which individuals and throat irritation on inhalation.

516

SODIUM PICOSULFATE SPACE MEDICINE

sodium picosulfate A stimulant laxative somatic A term meaning related to the S
drug used to treat constipation and to body (soma), as opposed to the mind
empty the bowel prior to procedures (psyche), or related to body cells, as
such as X-ray, endoscopy, and surgery opposed to germ cells (eggs and sperm).
on the intestines. Side effects may It also refers to the body wall, in con-
include abdominal cramps and diar- trast to visceral (of the internal organs).
rhoea. The drug should be avoided in
cases of intestinal obstruction. somatization disorder A condition in
which a person complains over a period
sodium valproate An anticonvulsant of several years of various physical prob-
drug used to treat epilepsy. Possible lems for which no organic cause can be
side effects include drowsiness, abdom- found. The disorder, which is more com-
inal discomfort, temporary hair loss, mon in women, usually begins before
weight gain, and rash. Prolonged treat- age 30 and leads to numerous tests by
ment may rarely cause liver damage. many doctors. Unnecessary surgery and
other treatments may result. The condi-
soft-tissue injury Damage to the tis- tion is often associated with anxiety,
sues (see ligament; tendon; muscle) that depression, or substance abuse. (See also
surround bones and joints. conversion disorder; hypochondriasis.)

soiling Inappropriate passage of faeces somatostatin analogues Synthetic ver-
after the age at which bowel control is sions of the hormone somatostatin that
achieved (usually at about 3 or 4 years). acts on the pituitary gland, controlling
Causes include slowness in developing the release of growth hormone. These
bowel control, longstanding constipation, drugs are used to treat acromegaly and
poor toilet-training, and emotional stress. symptoms associated with some other
Soiling due to constipation is usually hormone-secreting tumours (particularly
resolved with treatment. If there is no in carcinoid syndrome). Octreotide is a
physical cause, psychotherapy may help. common somatostatin analogue.
Encopresis is a form of soiling in which
children deliberately pass faeces in inap- somatotype A person’s physical build.
propriate places, such as behind furniture. somatropin A biosynthetic growth hor-

solar plexus The largest network of mone given to children to treat short
autonomic nerves in the body, located stature due to growth-hormone deficiency.
behind the stomach between the adrenal somnambulism See sleepwalking.
glands. The solar plexus incorporates sore A term used nominally to describe
branches of the vagus nerve and the any disrupted area of the skin or mucous
splanchnic nerves, and sends branches membranes, or adjectivally to describe
into the stomach, intestines, and other an area that is tender or painful.
abdominal organs. sore throat A rough or raw feeling in
the back of the throat that causes dis-
solvent abuse The practice of inhaling comfort, especially when swallowing.
the intoxicating fumes given off by cer-
tain volatile liquids. Glue sniffing is the Sore throat is a common symptom,
most common form. usually caused by pharyngitis and occa-
Inhalation of solvent fumes produces sionally by tonsillitis. It is often the first
a feeling of intoxication similar to that symptom of the common cold, influenza,
produced by alcohol. Solvent abuse can laryngitis, infectious mononucleosis, and
cause headache, vomiting, confusion, many childhood viral illnesses, such as
and coma. Death may occur due to a chickenpox, measles, and mumps.
direct toxic effect on the heart, a fall,
choking on vomit, or asphyxiation. Long- A sore throat may be relieved by gar-
term effects include erosion of the lining gling with salt water. Sore throats due
of the nose and throat, and damage to to bacterial infection are treated with
the kidneys, liver, and nervous system. antibiotic drugs. (See also strep throat.)
Acute symptoms resulting from solvent space medicine A medical speciality
abuse require urgent medical attention. concerned with the physiological effects
Counselling may be helpful in discour- of space flight. For example, weightless-
aging the behaviour. ness upsets the balance mechanisms of
the inner ear, causing motion sickness.

517

SPASM SPERM

spasm An involuntary contraction of a speech disorders Defects or disturb-

muscle. Examples include hiccups and ances in speech that lead to an inability

tics. Disorders characterized by spasm in- to communicate effectively.

clude trigeminal neuralgia and tetanus. Damage to the language centres of the

spasticity Increased rigidity in a group brain (usually due to a stroke, head

of muscles, causing stiffness and restric- injury, or brain tumour) leads to aphasia,

tion of movement. Spasticity occurs in which may impair speech.

Parkinson’s disease, multiple sclerosis, Disorders of articulation may be caused

cerebral palsy, and tetanus. by damage to nerves that go to muscles

spastic paralysis Inability to move a in the larynx, mouth or lips, due to

part of the body, accompanied by rigidity stroke, head injury, multiple sclerosis, or

of the muscles. Causes of spastic para- Parkinson’s disease. A structural abnor-

lysis include stroke, cerebral palsy, and mality of the mouth, such as a cleft lip

multiple sclerosis. (See also paralysis.) and palate, can also be a cause.

specific gravity The ratio of the dens- Disorders of voice production include

ity of a substance to that of water. hoarseness and inappropriate pitch or

specific learning disability Difficulty loudness. In many cases, the cause is a

in one or more areas of learning in a disorder affecting closure of the vocal

child of average or above average intel- cords (see larynx, disorders of). A voice

ligence. Specific learning disabilities that is too high or low or too loud or soft

include dyslexia and dyscalculia, where may be caused by a hormonal or psy-

there is a problem with mathematics. chiatric disturbance or by hearing loss.

specimen A sample of tissue, body fluids, Disorders of fluency include stuttering,

waste products, or an infective organism which is marked by hesitant speech and

taken for analysis, identification, and/or repetition of sounds.

diagnosis. The sample may be prepared Delayed speech development in a child

for examination under a microscope. may be due to hearing loss (see deaf-

SPECT The abbreviation for single pho- ness), slow maturation of the nervous

ton emission computed tomography, a system, poor tongue and lip control,

type of radionuclide scanning. lack of stimulation, or emotional distur-

spectacles See glasses. bance (see developmental delay).

speculum A device for holding open a Many people with speech disorders

body orifice to enable a doctor to per- can be helped by speech therapy.

form an examination. speech therapy A form of treatment

speech A system of sounds by which for people who have a speech disorder.

humans communicate. Children learn A speech therapist SPERM
speech through listening to and imitat- tests speech and

ing the speech of others. hearing and devises Acrosome

S Speech production originates in 2 exercises to improve
regions of the cerebral cortex on each the deficient aspect

side of the brain. These regions are linked of speech. Head

to the centre for language expression sperm The male sex

(Broca’s area) in the dominant hemi- cell, which is respon-

sphere. They send signals down nerve sible for fertilization

pathways to muscles controlling the lar- of the female ovum.

ynx, tongue, and other parts involved in Inside the head of

speech. The cerebellum plays a part in the sperm is genetic

coordinating movements of these parts. material, while the

Air from the lungs is vibrated through acrosome that caps Tail
the vocal cords in the larynx. This pro- the head contains

duces a noise, which is amplified in the enzymes that enable

cavities of the throat, nose, and sinuses. sperm to penetrate

The sound of the vibrated air is modified the ovum’s outer

by movements of the tongue, mouth, covering. The tail of

and lips to produce speech sounds. the sperm propels it.

518

SPERMATIC CORD SPINA BIFIDA

Sperm are produced within the seminif- sphincter, artificial A surgically creat-

erous tubules of the testes and mature in ed valve or other device used to treat or

the epididymis. Production and develop- prevent urinary or faecal incontinence.

ment of sperm cells is dependent on sphincterotomy A surgical procedure

testosterone and on gonadotrophin hor- that involves cutting the muscle that

mones secreted by the pituitary gland. closes a body opening or that constricts

Sperm production starts at puberty. the opening between body passages.

spermatic cord The structure in males sphygmomanometer An instrument

that runs from the abdomen to the used for measuring blood pressure. A

scrotum and contains the vas deferens. cuff attached to the device is wrapped

(See also reproductive system, male.) around the person’s arm and inflated

spermatocele A harmless cyst of the until it compresses the main artery in

epididymis containing fluid and sperm. the arm. The cuff is deflated while the

spermatozoa See sperm. doctor listens to the blood flow through

spermicides Contraceptive preparations a stethoscope. The sphygmomanometer

that kill sperm. They are usually recom- records the pressure on a mercury-filled

mended for use with a barrier device. glass column or a digital display.

SPF Sun protec- SPHYGMOMANOMETER
tion factor, the

degree of protec- Sphygmomanometer
tion a sunscreen

provides against

sunburn. It is a Stethoscope Inflatable
measure of the cuff

amount of UVB

radiation a sun-

screen absorbs:

the higher the

number, the more

the protection.

sphenoid bone

The bat-shaped

bone in the cen-

tre of the base of

the cranium.

spherocytosis,

hereditary An inherited disorder in spider bites Nearly all spiders produce

which there are a large number of venom, which they use to kill their prey.

unusually small, round red blood cells However, only a few species, such as the S

(spherocytes) in the circulation. These black widow in North America, are harm-

abnormal red cells are readily broken up ful to humans. Antivenoms are available

when blood passes through the spleen. for many dangerous spider bites.

At times, the rate of red cell destruction spider naevus A red, raised pinhead-

exceeds the rate at which new cells can sized dot, from which small blood

be made in the bone marrow, leading to vessels radiate, due to a dilated minor

symptoms of anaemia. Other symptoms artery and its connecting capillaries.

include jaundice and enlargement of the Small numbers of spider naevi are com-

spleen. Occasionally, crises occur (usu- mon in children and pregnant women,

ally triggered by infection) in which all but in larger numbers, they may indicate

symptoms worsen. Gallstones are a fre- liver disease. (See also telangiectasia.)

quent complication. Splenectomy usually spina bifida A congenital defect that is a

leads to permanent improvement. type of neural tube defect in which part

sphincter A ring of muscle around a of 1 or more vertebrae fails to develop

natural opening or passage that acts as completely. As a result, a portion of the

a valve, regulating inflow or outflow. spinal cord is left exposed.

519

SPINAL ANAESTHESIA SPINAL NERVES

spinal anaesthesia Injection of an spinal fusion Major surgery to join 2 or

anaesthetic into the cerebrospinal fluid more adjacent vertebrae. It is perfor-

in the spinal canal to block pain sensa- med if abnormal movement between

tions before they reach the central adjacent vertebrae causes severe back

nervous system. It is used mainly during pain or may damage the spinal cord.

surgery on the lower abdomen and legs. spinal injury Damage to the spine and

(See also epidural anaesthesia.) sometimes to the spinal cord. Spinal

spinal cord A cylinder of nerve tissue injury is most often the result of falling

that runs from the brain, down the cen- from a height or of a road traffic accident.

tral canal in the spine to the 1st lumbar Damage to the vertebrae and their liga-

vertebra. Below that, the nerve roots con- ments usually causes severe pain and

tinue within the canal as cauda equina. swelling of the affected area. Damage to

Grey matter, the spinal cord’s core, con- the spinal cord results in paralysis and/or

tains the cell bodies of nerve cells. loss of sensation below the site of injury.

Areas of white matter (tracts of nerve X-rays of the spine are carried out to

fibres running lengthwise) surround the determine the extent of damage. If the

grey matter. Sprouting from the cord on bones are dislocated, surgery is needed

each side at regular intervals are the sen- to manipulate them back into position.

sory and motor spinal nerve roots. The Treatment with the drug methylpred-

small nodule (ganglion) in each sensory nisolone within a few hours of an injury

root comprises nerve cell bodies. Nerve aids recovery from spinal-cord damage.

roots combine to form the spinal nerves Surgery may be needed to remove any

that link the spinal cord to all regions of pressure on the cord, but damaged nerve

the trunk and limbs. The entire spinal tracts cannot be repaired. Physiotherapy

cord is bathed in cerebrospinal fluid and may stop joints locking and muscles

surrounded by the meninges. contracting as the result of paralysis.

The nerve tracts in the white matter act If there is no spinal-cord damage,

mainly as highways for sensory informa- recovery is usually complete. In cases of

tion passing up to the brain or motor spinal-cord damage, some improve-

signals passing down. However, the cord ment may occur for up to 12 months.

processes some sensory information spinal nerves A set of 31 pairs of nerves

itself and provides motor responses that connect to the spinal cord. Spinal

without involving the brain. Many reflex nerves emerge in 2 rows from either side

actions are controlled in this way. of the spinal cord and leave the spine

The spinal cord may be injured by through gaps between adjacent verte-

trauma (see spinal injury); spinal-cord brae. The nerves then branch out to

infections such as poliomyelitis are rare supply all parts of the trunk, arms, and

but can cause serious damage. legs with sensory and motor nerve fibres.

S SPINAL CORD

Brain Sensory Grey matter
nerve root
Spinal White matter
cord Spinal
nerve Motor
nerve
root

Cauda
equina

Spinal Ganglion
nerve STRUCTURE OF SPINAL CORD

Meninges

LOCATION

520

SPINAL TAP SPLEEN

Disc prolapse may lead to pressure on spirochaete A spiral-shaped bacterium.
Spirochaetes cause syphilis, leptospirosis,
a spinal nerve, causing pain. Injury to a relapsing fever, and Lyme disease.

nerve may lead to loss of sensation or spirometry A pulmonary function test
used to diagnose or assess a lung disor-
movement in the area supplied by the der or to monitor treatment. It records the
rate at which a person exhales air from
nerve. (See also nerve injury; neuropathy.) the lungs and the total volume exhaled.

spinal tap See lumbar puncture.

spine The column of bones and carti-

lage that extends from the base of the

skull to the pelvis, enclosing the spinal SPIROMETRY

cord and supporting the trunk and head.

The spine is made up of 33 roughly Monitor Nose clip

cylindrical vertebrae. Each pair of adja-

cent vertebrae is connected by a facet Spirometer

joint, which stabilizes the vertebral col-

umn. Between each pair of vertebrae lies

a disc-shaped pad of cartilage called an

intervertebral disc (see disc, interverte-

bral). These discs cushion the vertebrae

during movement. The vertebrae are

bound together by 2 ligaments running

the length of the spine and by smaller

ligaments between each vertebra.

SPINE Attached to the
vertebrae are sev-

Cervical eral groups of
spine (7 muscles, which
vertebrae) control movement

of, and help to

support, the spine.

spine, disorders

of Many disorders spironolactone A potassium-sparing
diuretic drug, which is given to treat
of the spine cause heart failure. Spironolactone may cause
numbness, weakness, and nausea. Less
back pain. Spina common side effects include diarrhoea,
lethargy, impotence, rash, and irregular
Thoracic bifida is a congen- menstruation. High doses may cause
spine (12 ital disorder in abnormal breast enlargement in men.
vertebrae) which part of the
spleen An organ that removes worn-out
spinal cord is ex- and defective red blood cells from the
circulation and helps to fight infection by
posed. Sometimes, producing some of the antibodies, lym-
phocytes, and phagocytes that destroy
the spine is abnor- invading microorganisms. The spleen is S
a fist-sized, spongy organ in the upper
Lumbar mally curved (see left abdomen behind the lower ribs.
spine (5 lordosis, kyphosis, The spleen enlarges in many diseases.
vertebrae) scoliosis). In ankylo- These include infections such as malaria
sing spondylitis, and and infectious mononucleosis; blood dis-
orders such as leukaemia, thalassaemia,
in some cases of and sickle cell anaemia; and tumours
such as lymphomas. Enlargement of the
rheumatoid arth- spleen may be accompanied by hyper-
splenism. The spleen may be ruptured by
ritis, spinal joints a severe blow to the abdomen. This can

are affected; osteo-

arthritis affects the

spinal joints of

Sacrum most people over
(5 fused 60. Other disorders
vertebrae) affecting the spine

Coccyx are spinal injuries;
(4 fused disc prolapse, and
vertebrae) spondylolisthesis.

521

SPLENECTOMY SPRUE

cause potentially fatal haemorrhage, and orally usually clears up the infection.

an emergency splenectomy is needed. Rarely, in people with reduced immunity,

splenectomy Surgical removal of the sporotrichosis spreads to other parts of

spleen. Splenectomy is performed after the body and requires treatment with

the spleen has been seriously injured or amphotericin, an antifungal drug .

to treat hypersplenism or certain forms sport, drugs and Four main types of

of anaemia. The absence of the spleen drug are abused by athletes to enhance

does not normally cause problems; its physical or mental condition. Stimulants

function is largely taken over by other such as amfetamines can prevent fatigue

parts of the lymphatic system and by the and increase confidence. Three types of

liver. People who have had a splenec- hormone drugs may be abused: anabolic

tomy are more susceptible to certain steroids (see steroids, anabolic) to speed

infections and are given pneumococcal muscle recovery after exercise; erythropo-

vaccine and long-term antibiotics. ietin to boost the haemoglobin content

splint A device used to immobilize a of the blood, which may increase stam-

part of the body. ina; and growth hormone to stimulate

splinter haemorrhage Bleeding under muscle growth. Analgesic drugs may be

the fingernails visible as tiny splinter- used to mask the pain of an injury. Beta-

like marks. Usually due to trauma, it can blockers are taken to reduce tremor in

also be a sign of infective endocarditis. sports that require a steady hand. Aside

splinting The application of a splint, from the health risks associated with

most often used to immobilize a frac- abuse of these drugs, their use is pro-

tured or otherwise injured limb or digit. hibited in many competitive sports.

splinting, dental The mechanical join- sports injuries Any injury that arises

ing of several teeth to hold them firmly during sports participation. Typical

in place while an injury heals or while sports injuries include fractures, head

periodontal disease is treated. injury (including concussion), muscle

split personality A common term for strain or compartment syndrome, liga-

multiple personality. It is also used, ment sprain, tendinitis or tendon rupture,

incorrectly, to describe schizophrenia. and joint dislocation or subluxation. Some

spondylitis Inflammation of the joints so-called sports injuries, such as tennis

between the vertebrae in the spine. It is elbow, are in fact a type of overuse injury.

usually caused by osteoarthritis, rheum- sports medicine The medical speciality

atoid arthritis, or ankylosing spondylitis. concerned with assessment and improve-

spondylolisthesis The slipping forwards ment of fitness and the treatment and

(or occasionally backwards) of a verte- prevention of disorders related to sports.

bra over the one below it. spot A general term for a small lump,

spondylolysis A disorder of the spine in mark, or inflamed area on the skin.

S which the arch of the 5th (or, rarely, the spotting See breakthrough bleeding.
4th) lumbar vertebra consists of soft sprain Tearing or stretching of the liga-

fibrous tissue instead of normal bone. As ments that hold together the bone ends

a result, the arch is weak and prone to in a joint, caused by a sudden pull. The

damage under stress, which may produce ankle is the most commonly sprained

spondylolisthesis. Otherwise, spondyloly- joint. A sprain causes painful swelling

sis is usually symptomless. See cervical of the joint, which cannot be moved

spondylosis; cervical osteoarthritis. without increasing the pain. There may

sporotrichosis A chronic infection cau- also be spasm of surrounding muscles.

sed by the fungus SPOROTHRIX SCHENCKII, Treatment consists of applying an ice-

which grows on plants. The infection is pack, wrapping the joint in a bandage,

most often contracted through a skin resting it in a raised position, and tak-

wound; gardeners are particularly vul- ing analgesic drugs. In severe cases,

nerable. An ulcer develops at the site of surgical repair may be necessary.

the wound, followed by the formation sprue An intestinal disorder causing

of nodules in lymph channels around failure to absorb nutrients from food.

the site. Potassium iodide solution taken (See also sprue, tropical; coeliac disease.)

522

SPRUE, TROPICAL STAPEDECTOMY S

sprue, tropical A disease of the small suppresses the image from the deviating
intestine that causes failure to absorb eye, leading to amblyopia.
nutrients from food. It occurs mainly in
India, the Far East, and the Caribbean. In adults, squint may be a symptom of
Sprue leads to malnutrition and mega- stroke, diabetes mellitus, multiple scler-
loblastic anaemia. It may be due to an osis, hyperthyroidism, or a tumour. A
intestinal infection. Symptoms include squint in adults causes double vision.
appetite and weight loss, an inflamed
mouth, and fatty diarrhoea. Diagnosis is Treatment in children up to 6–7 years
confirmed by jejunal biopsy. Sprue resp- may include covering the normal eye with
onds well to antibiotic drug treatment a patch to force the child to use the weak
and vitamin and mineral supplements. eye. Deviation of the squinting eye may
be controlled by glasses and/or surgery.
sputum Mucous material produced by Sudden onset of a squint in adults may
cells lining the respiratory tract. Sputum have a serious underlying cause and
production may be increased by respira- must be investigated promptly.
tory tract infection, an allergic reaction SSRIs See selective serotonin reuptake
(see asthma), or inhalation of irritants. inhibitors.
stable A term used in medicine to des-
squamous cell carcinoma One of the cribe a patient’s condition that is neither
most common types of skin cancer. deteriorating nor improving; a personal-
Squamous cell carcinoma is linked to ity that is not susceptible to mental
long-term exposure to sunlight. It is most illness; or a chemical substance that is
common in fair-skinned people over 60. resistant to changes in its composition
The tumour starts as a small, painless or physical state, or is not radioactive.
lump or patch (usually on the lip, ear, or stage A term used in medicine to refer
back of the hand), which enlarges fairly to a phase in the course of a disease,
rapidly, often resembling a wart or ulcer. particularly in the progression of cancer.
Left untreated, the cancer may spread to staining The process of dyeing specimens
other parts of the body and prove fatal. of cells, tissues, or microorganisms in
Diagnosis is based on a skin biopsy. order for them to be clearly visible or
The tumour is removed surgically or easily identifiable under a microscope.
destroyed by radiotherapy. stammering See stuttering.
Stanford–Binet test A type of intelli-
squint An abnormal deviation of 1 eye gence test.
relative to the other. Many babies have a stanozolol A type of anabolic steroid
squint because the mechanism for align- drug (see steroids, anabolic).
ing the eyes has not yet developed. A stapedectomy An operation on the ear
squint that starts later in childhood is to remove the stapes and replace it with
usually due to breakdown of the align- an artificial substitute. It is used to treat
ment mechanism. Longsightedness is a deafness due to otosclerosis.
common factor. In some cases, the brain

STAPEDECTOMY

Bony Inner ear Prosthetic Hole in
overgrowth piston bony area

LOCATION Area of
Middle ear stapes
Eardrum to be
removed

Base of
stapes

BEFORE SURGERY AFTER SURGERY
523

STAPES STEM CELL

stapes The innermost of the 3 tiny, steam inhalation A method of relieving

sound-conducting bones in the middle some of the symptoms of colds, sinusi-

ear. The stapes is the smallest bone in tis, and laryngitis by breathing in hot

the body. Its head articulates with the vapour from a bowl of hot water. The

incus, and its base fits into the oval moisture loosens secretions in the nose

window in the wall of the inner ear. and throat, making them easier to clear.

In otosclerosis, the stapes becomes STEAM INHALATION
fixed and cannot transmit sound to the

inner ear. Resultant hearing loss can be Towel
treated by stapedectomy.

staphylococcal infections Infections Hot
caused by bacteria of the genus STAPHYLO- water
COCCUS. Different types of staphylococci

are responsible for a variety of disorders,

including skin infections such as pus-

tules, boils, and abscesses, and a rash in

newborn babies (see necrolysis, toxic

epidermal); pneumonia; toxic shock syn-

drome in menstruating women; urinary

tract infection; food poisoning; and, if the

bacteria enter the circulation, septic

shock, infectious arthritis, osteomyelitis,

or bacterial endocarditis.

starch See carbohydrates.

starvation A condition caused by lack

of food over a long period, resulting in

weight loss, changes in metabolism, and steatorrhoea The presence of excessive

extreme hunger. (See also anorexia ner- fat in the faeces. Steatorrhoea causes

vosa; fasting; nutritional disorders.) offensive-smelling, bulky, loose, greasy,

stasis Slowing down or cessation of flow. pale-coloured faeces, which float in the

statins A type of lipid-lowering drug used toilet. Steatorrhoea may occur in panc-

to treat high blood levels of cholesterol reatitis and coeliac disease and after the

or to lower blood lipid levels in people removal of substantial segments of

with coronary artery disease. small intestine. It is also a side effect

statistics, medical The collection and of some lipid-lowering drugs.

analysis of numerical data relating to Stein-Leventhal syndrome See ovary,

medicine. Information on the incidence polycystic.

and prevalence of various conditions is stem cell A basic cell in the body from

S an important aspect of medical statistics. which more specialized cells are formed.
statistics, vital Assessment of a popu- Stem cells within the bone marrow pro-

lation’s health that relies on the duce blood cells through a series of

collection of data on birth and death maturation steps. Stem cells are found

rates and on the causes of death. in blood and can be transplanted as an

status asthmaticus A severe and pro- alternative to bone marrow transplanta-

longed attack of asthma. This is a tion. Stem cells can be obtained from a

potentially life-threatening condition donor sibling, a matched but unrelated

that requires urgent treatment. donor, or from stored umbilical blood.

status epilepticus Prolonged or repea- Patients can also act as their own

ted epileptic seizures without recovery donors, with cells harvested and stored

of consciousness between attacks. This to be reinfused later after treatment has

is a medical emergency that may be damaged the bone marrow. Stem-cell

fatal if not treated promptly. It is more transplantation is used mainly for peo-

likely to occur if anticonvulsant drugs ple being treated for leukaemia and

are taken erratically or if they are with- other cancers but may, in the future, be

drawn suddenly. (See also epilepsy.) used for noncancerous disorders.

524

STENOSIS STETHOSCOPE

stenosis Narrowing of a duct, canal, to prevent sperm reaching the ova.

passage, or tubular organ. Female sterilization is usually per-

stent A rigid tube that is surgically inser- formed by laparoscopy, which involves 2

ted to open up or keep open any body small incisions in the abdomen. Some-

canal that may have become narrowed or times it is done by minilaparotomy, in

closed up due to disease. Stents are used which a single incision is made in the

to open narrowed coronary arteries in pubic area. The fallopian tubes are

heart disease. They are also used to sealed using clips or by cutting and

relieve blockages caused by a tumour, for tying. The operations have a low failure

example in the oesophagus or pancreas. rate. Fertility can sometimes be restored

sterculia A bulk-forming laxative used to after sterilization using microsurgery.

treat constipation. It is especially useful sterilization, male See vasectomy.

when stools are small and hard. Stercu- sternum The long, narrow, flat plate of

lia should only be used if fibre intake bone at the front of the chest. The ster-

cannot be increased; adequate fluid num has 3 parts: an upper, triangular

intake must be maintained to avoid in- portion (manubrium); a long middle part

testinal obstruction. Side effects may (body); and, at the lower end, a small,

include flatulence, bloating, and gastro- leaf-shaped projection (xiphoid process).

intestinal obstruction or impaction. The upper manubrium articulates with

stereotaxic surgery Brain operations the inner ends of the clavicles. The ribs

carried out by inserting delicate instru- are attached to the sides of the manubri-

ments through a surgically created hole um and body by cartilage. Between the

in the skull and guiding them, with the manubrium and body is a symphysis

aid of CT scanning, to a specific area. joint, allowing slight movement when

Stereotaxic procedures can be used to the ribs rise and fall during breathing.

treat pituitary tumours; for a brain biopsy; Great force is required to fracture the

or to destroy small areas of the brain to sternum. The main danger of such an

treat disabling neurological disorders. injury is the possibility that the broken

sterility The state either of being germ- bone may be driven inwards, damaging

free or of permanent infertility. the heart, which lies behind the sternum.

sterilization The complete destruction steroid drugs A group of drugs includ-

or removal of living organisms, usually to ing corticosteroid drugs and anabolic

prevent spread of infection; any proce- steroids (see steroids, anabolic).

dure that renders a person infertile (see steroids, anabolic Drugs that have an

sterilization, female; vasectomy). anabolic (protein-building) effect similar

sterilization, female A usually perma- to testosterone. Anabolic steroids build

nent method of contraception in which tissue, promote muscle recovery after

the fallopian tubes are sealed in order an injury, and strengthen bones. They

STERILIZATION, FEMALE are used to treat S
some types of

Fallopian tube anaemia. Anabolic
steroids are often

abused by athletes.

Clip blocking Possible adverse

fallopian tube effects of the drugs

include acne, oede-

Ovary ma, damage to the
liver and adrenal

Uterus glands, infertility,
impotence in men,
Cervix and virilization in

women.

Vagina stethoscope An

instrument that is

SITES OF INCISION LAPAROSCOPIC CLIP STERILIZATION used for listening

525

STEVENS–JOHNSON SYNDROME STOMACH

STETHOSCOPE Still’s disease See rheumatoid arthritis,
juvenile.

Tubing stimulant drugs Drugs that increase

brain activity by initiating the release of

noradrenaline (norepinephrine). Stimu-

lants are of 2 types: central nervous

Diaphragm of system stimulants (for example, amfe-
stethoscope tamines), which increase alertness; and

respiratory stimulants (see analeptic

drugs), which encourage breathing.

stimulus Anything that directly results

in a change in the activities of the body

as a whole or of any individual part.

stings Stinging animals include scorpi-

ons, some insects, jellyfish, and some

fish (see venomous bites and stings).

Stinging plants may cause an allergic

to sounds in the body, particularly skin reaction. (See also poisonous plants.)

those made by the heart or lungs. STIs See sexually transmitted infections.

Stevens–Johnson syndrome A rare, stitch A temporary, sudden, sharp pain

life-threatening form of erythema multi- in the abdomen or side that occurs dur-

forme characterized by severe blisters and ing severe or unaccustomed exercise.

bleeding in the mucous membranes of Stitch is also the common name for a

the eyes, mouth, nose, and genitals. suture (see suturing) to close a wound.

sticky eye One of the symptoms of con- St. John’s wort A herbal remedy derived

junctivitis in which the eyelids become from the plant HYPERICUM PERFORTUM.

stuck together with discharge. Capsules or infusions taken orally are

stiff neck A common symptom, usually effective in treating mild depression. St.

due to spasm in muscles at the side or John’s wort is also used in creams for

back of the neck. In most cases, it occurs burns, wounds, and joint problems.

suddenly and for no apparent reason. It However, St John’s wort interacts with a

may result from a neck injury, such as a wide variety of other medications. Peo-

ligament sprain, disc prolapse, or whip- ple should not take a St John’s wort

lash injury. A rare cause is meningitis. preparation without first consulting a

Mild stiffness may be relieved by mas- doctor or pharmacist.

sage, warming, and use of a liniment. Stokes–Adams syndrome Recurrent

Severe or persistent stiffness requires episodes of temporary loss of conscious-

medical attention. (See also torticollis.) ness caused by insufficient blood flow

S stiffness A term used to describe difficulty from the heart to the brain. This is due to
in moving a joint or stretching a muscle. irregularity of the heartbeat (see arrhyth-

stilboestrol A drug that mimics the mia, cardiac) or to complete heart block.

natural oestrogen hormone estradiol. It Most people with the syndrome are fit-

is occasionally used to treat prostate can- ted with a pacemaker to prevent attacks.

cer. Side effects are those of oestrogens. stoma A term meaning mouth or orifice.

stillbirth Delivery of a dead fetus after A stoma can be created surgically in the

the 24th week of pregnancy. The cause is abdominal wall (see colostomy; ileost-

unknown in many cases. Some stillborn omy) to allow the intestine to empty into

babies have severe malformations, such a bag or pouch on the surface of the skin.

as anencephaly, spina bifida, or hydro- stomach A hollow, bag-like organ of the

cephalus. Other possible causes include digestive system located in the left side

a maternal disorder, such as antepartum of the abdomen under the diaphragm.

haemorrhage or hypertension, or severe Food enters the stomach from the

Rhesus incompatibility. The risk of still- oesophagus and exits into the duodenum.

birth is increased if the mother has a The sight and smell of food, and its

severe infection during pregnancy. arrival in the stomach, stimulate gastric

526

STOMACHACHE STRANGURY

STOMACH There may also be other symptoms indis-
tinguishable from those of peptic ulcer.
Oesophagus
Diagnosis is usually made by gastros-
Oesophageal LOCATION copy or by a barium X-ray examination.
sphincter Muscle layers The only effective treatment is total gas-
trectomy. In advanced cases in which the
Pyloric Ruga tumour has spread, radiotherapy and
sphincter anticancer drugs may prolong life.
stomach, disorders of the The stom-
Duodenum Mucosa ach may be affected by various disorders,
Submucosa including gastrointestinal infections, pep-
tic ulcers, gastritis, pyloric stenosis,
secretion from the stomach lining. Gas- volvulus, polyps, and stomach cancer. S
tric juice contains pepsin, an enzyme that stomach imaging See barium X-ray
breaks down protein; hydrochloric acid, examinations.
which kills bacteria and creates the opti- stomach pump See lavage, gastric.
mum pH for pepsin activity; and intrinsic stomach ulcer A type of peptic ulcer.
factor, which is essential for absorption stomatitis Any form of inflammation or
of vitamin B12 in the small intestine. The ulceration of the mouth.
gastric lining also secretes mucus to stones Small, hard collections of solid
stop the stomach digesting itself. material within the body. (See also cal-
culus, urinary tract; gallstones.)
The muscular stomach wall produces stool Another word for faeces.
rhythmic contractions that churn the food stork mark A small, flat, harmless,
and gastric juice to aid digestion. Partly pinkish-red skin blemish found in many
digested food is squirted into the duo- newborn babies. Such marks, which may
denum at regular intervals by stomach be temporary, are a type of haeman-
contractions and by relaxation of the gioma and are usually found around the
ring of muscle at the stomach outlet. eyes and at the nape of the neck.
stomachache Discomfort in the upper strabismus See squint.
abdomen. (See also indigestion.) strain Tearing or stretching of muscle
stomach cancer A malignant tumour fibres as a result of suddenly pulling
that arises from the lining of the stomach. them too far. There is bleeding into the
The exact cause is unknown, but HELICO- damaged area of muscle, causing pain,
BACTER PYLORI infection is thought to be swelling, muscle spasm, and bruising.
linked to increased incidence. Other like-
ly factors include smoking and alcohol Treatment may include applying an ice-
intake; diet may also play a part, in par- pack, resting the affected part, taking
ticular eating large amounts of salted or analgesic drugs, and physiotherapy.
pickled foods. Pernicious anaemia, a par- strangulation The constriction, usually
tial gastrectomy, and belonging to blood by twisting or compression, of a tube or
group A also seem to increase the risk. passage in the body, blocking blood
Stomach cancer rarely affects people flow and interfering with the function of
under 40 and is more common in men. the affected organ. Strangulation may
occur with a hernia, for example.

Strangulation of the neck causes com-
pression of the jugular veins, preventing
blood from flowing out of the brain, and
compression of the windpipe, which
restricts breathing. The victim loses con-
sciousness, and brain damage and death
from lack of oxygen follow.
strangury A symptom characterized by
a painful and frequent desire to empty
the bladder, although only a few drops
of urine can be passed. Causes include

527

STRAPPING STRIDOR

prostatitis, cystitis, bladder cancer (see Continued exposure to stress often

bladder tumours), and bladder stones leads to mental and physical symptoms,

(see calculus, urinary tract). such as anxiety and depression, indiges-

strapping The application of adhesive tion, palpitations, and muscular aches

tape to part of the body to exert pres- and pains. Post-traumatic stress disorder

sure and hold a structure in place. is a direct response to a specific stressful

strawberry naevus A bright red, raised event. (See also relaxation techniques.)

spot which appears in early infancy. It is stress fracture A fracture that occurs as

a type of haemangioma. a result of repetitive jarring of a bone.

strep throat A streptococcal infection of Common sites include the metatarsal

the throat. It is most common in chil- bones in the foot (see March fracture),

dren. The bacteria are spread in droplets the tibia or fibula, the neck of the femur,

coughed or breathed into the air. and the lumbar spine. The main symp-

In some people, the bacteria cause no toms are pain and tenderness at the

symptoms, but others suffer a sore throat, fracture site. Diagnosis is by bone imag-

fever, and enlarged lymph nodes in the ing. Treatment consists of resting the

neck. In some cases, the bacterial toxins affected area for 4–6 weeks. The fracture

produce a rash (see scarlet fever). may be immobilized in a cast.

Treatment is usually with a penicillin stress ulcer An acute peptic ulcer that

drug. Untreated, strep throat may lead develops after shock, severe burns or

to glomerulonephritis or rheumatic fever. injuries, or during a major illness. Stress

streptococcal infections Infections ulcers are usually multiple and are most

caused by bacteria of the STREPTOCOCCUS common in the stomach. The exact

group. A particular type, haemolytic strep- cause is unknown. Drugs are often given

tococci, can cause tonsillitis, strep throat, to severely ill patients in hospital to pre-

scarlet fever, otitis media, pneumonia, ery- vent the development of stress ulcers.

sipelas, and wound infections. Another stretcher A frame covered with fabric

type is often responsible for urinary tract that is used in first aid for carrying the

infection, and another can cause bacterial sick, injured, or deceased.

endocarditis if it enters the bloodstream. stretch-mark Another name for stria.

streptokinase A thrombolytic drug used stria Also called a stretch-mark, a line on

to dissolve blood clots following a myo- the skin caused by thinning and loss of

cardial infarction or pulmonary embolism. elasticity in the dermis. Striae first appear

Side effects include nausea, rash, and as red, raised lines. Later they become

cardiac arrhythmias. purple, eventually fading to shiny streaks.

streptomycin An antibiotic drug used to Striae often develop on the hips and

treat a number of uncommon infections, thighs during the adolescent growth

including tularaemia, plague, brucellosis, spurt, especially in athletic girls. They are

S and glanders. It may damage nerves in a common feature of pregnancy, occur-
the inner ear, disturbing balance and ring on the breasts, thighs, and lower

causing dizziness, tinnitus, or deafness. abdomen. Purple striae are a character-

Other side effects are facial numbness, istic feature of Cushing’s syndrome.

tingling in the hands, and headache. Striae are thought to be caused by an

stress Any interference that disturbs a excess of corticosteroid hormones. There

person’s mental and physical well-being. is no means of prevention, but in some

Stress may be experienced in response cases laser treatment may be used.

to a range of physical and emotional stricture Narrowing of a duct, canal, or

stimuli. When faced with stressful situ- other passage in the body.

ations, the body responds by increasing stridor An abnormal breathing sound

production of the hormones adrenaline caused by narrowing or obstruction of

(epinephrine) and cortisol, which pro- the larynx or trachea. Stridor is most

duce changes in heart-rate, blood common in young children. It usually

pressure, and metabolism to improve occurs in croup. Other causes include

performance. However, at a certain level, epiglottitis, an inhaled foreign body, hy-

they disrupt a person’s ability to cope. pocalcaemia, and some larynx disorders.

528

STROKE STRYCHNINE POISONING

stroke Damage to part of the brain caused stroma The tissue that forms an organ’s S
by an interruption to its blood supply. framework, as distinct from the functional
The interruption is most often due to the tissue (the parenchyma) and the fibrous
blockage of a cerebral artery by a blood outer layer that holds the organ together.
clot, which may have formed within the
artery (see thrombosis), or may have strongyloidiasis An infestation of the
been carried into the artery in the circu- intestines by the parasitic worm STRONGY-
lation from a clot elsewhere in the body LOIDES STERCORALIS. It is widespread in
(see embolism). Stroke may also result the tropics. Strongyloidiasis is contract-
from localized haemorrhage due to rup- ed in affected areas by walking barefoot
ture of a blood vessel in or near the brain. on soil contaminated with faeces. Larvae
The incidence of stroke rises with age penetrate the soles, migrating via the
and is higher in men. Certain factors in- lungs and throat to the intestine. Here
crease the risk. The most important are they develop into adults and produce
hypertension and atherosclerosis (and, larvae. Most larvae are passed in the fae-
by association, factors such as smoking ces, but some enter the skin around the
that contribute to these disorders). Other anus to begin a new cycle. A person
risk factors are atrial fibrillation, a damaged may be infested for more than 40 years.
heart valve, and a recent myocardial The larvae cause itching and red weals
infarction; these can cause clots in the where they enter the skin. In the lungs
heart which may migrate to the brain. they may cause asthma or pneumonia.
Symptoms usually develop abruptly Heavy intestinal infestation may cause
and, depending on the site, cause, and swelling of the abdomen and diarrhoea.
extent of brain damage, may include Occasionally, an infected person with
headache, dizziness, visual disturbance, reduced immunity dies of complica-
and difficulty in swallowing. Sensation, tions, such as septicaemia or meningitis.
movement, or function controlled by the Treatment with an anthelmintic drug,
damaged area of the brain is impaired. usually tiabendazole, kills the worms.
Weakness or paralysis on one side of the
body, called hemiplegia, is a common strontium A metallic element occurring
effect of a serious stroke. A stroke that in various compounds in certain miner-
affects the dominant cerebral hemisphere als, seawater, and marine plants.
may cause disturbance of language (see A radioactive variety, strontium 90, is
aphasia). About a third of major strokes produced during nuclear reactions and
are fatal, a third result in some disabil- may be present in nuclear fallout. Stron-
ity, and a third have no lasting ill effects tium 90 accumulates in bone, where the
(see transient ischaemic attack). radiation it emits may cause leukaemia
In some cases, urgent treatment may and/or bone tumours. Other forms of
improve the chances of recovery. ECG, radioactive strontium have been used
CT scanning, chest X-rays, blood tests, to diagnose and treat bone tumours.
angiography, and MRI may be used to
investigate the cause and extent of brain strychnine poisoning Strychnine is a
damage. If a stroke is proven by scan to poisonous chemical found in the seeds
be due to thrombosis, thrombolytic drugs of Strychnos species (tropical trees and
may be given. Anticoagulants may be shrubs). Its main use is as an ingredient
given if there is an obvious source of an in some rodent poisons; most cases of
embolism, such as atrial fibrillation or a strychnine poisoning occur in children
narrowed carotid artery. In some cases, who accidentally eat such poisons.
antiplatelet agents such as aspirin are Symptoms begin soon after ingestion
given. In most cases, attention to hydra- and include restlessness, stiffness of the
tion and pressure areas, and good nursing face and neck, increased sensitivity of
care, are the most important influences hearing, taste, and smell, and photosensi-
on outcome. Physiotherapy may restore tivity, followed by alternating episodes of
lost movement or sensation; speech seizures and floppiness. Death may occur
therapy may help language disturbances. from respiratory arrest.
The victim is given intravenous injec-
tions of a tranquillizer or a barbiturate,
with a muscle-relaxant drug if needed.

529

STUFFY NOSE SUBDURAL HAEMORRHAGE

Breathing may be maintained by a ven- of the neck may develop. Even uncon-

tilator. With prompt treatment, recovery scious patients may recover, but further

usually occurs in about 24 hours. attacks are common and often fatal.

stuffy nose See nasal congestion. Diagnosis is by CT scanning and angio-

stump The end portion of a limb that graphy. Treatment includes life-support

remains after amputation. procedures and control of blood pressure

stupor A state of almost complete un- to prevent recurrence. Burst or leaking

consciousness from which a person can aneurysms are usually treated by surg-

be aroused only briefly and by vigorous ery. About half of those people affected

external stimulation. (See also coma.) survive, some recover completely, others

Sturge–Weber syndrome A rare, con- have residual disability such as paralysis.

genital condition that affects the skin and subclavian steal syndrome Recurrent

the brain. Characteristically, a large pur- attacks of blurred or double vision, loss

ple birthmark (port wine stain) extends of coordination, or dizziness caused by

over one side of the face, including the reduced blood flow to the base of the

eye. Malformation of cerebral blood ves- brain when one arm (usually the left) is

sels may cause weakness on one side of moved. The cause is narrowing of the

the body, progressive mental handicap, arteries that carry blood to the arms,

and epilepsy. Glaucoma may develop in usually due to atherosclerosis. Treat-

the affected eye, leading to loss of vision. ment is by arterial reconstructive surgery.

Seizures can usually be controlled with subclinical A term applied to a disor-

anticonvulsant drugs. In severe cases, der that produces no symptoms or

brain surgery may be necessary. signs because it is either mild or in the

stuttering A speech disorder in which early stages of development.

there is repeated hesitation and delay in subconjunctival haemorrhage Bleed-

uttering words, unusual prolongation of ing under the conjunctiva that is usually

sounds, and repetition of word elements. harmless and disappears in a few days

Stuttering usually starts before the age without treatment.

of 8 and may continue into adult life. It is subconscious A term describing mental

more common in males, twins, and left- events (such as thoughts) of which one

handed people, and may occur with tics is temporarily unaware but which can be

or tremors. The severity may be related recalled under the right circumstances.

to social circumstances. The exact cause subcutaneous Beneath the skin.

is unknown, although it tends to run in subdural haemorrhage Bleeding into

families. Speech therapy often helps. the space between the outer and middle

St. Vitus’ dance An outdated term for layers of the meninges, usually following

Sydenham’s chorea. head injury. The trapped blood slowly

stye A small, pus-filled abscess at the forms a large clot within the skull that

S base of an eyelash, caused by infection. presses on brain tissue. The symptoms,
subacute A term used for a disease that which tend to fluctuate, may include

runs a course between acute and chronic. headache, confusion, drowsiness, and

subarachnoid haemorrhage A type of one-sided weakness or paralysis. The

brain haemorrhage in which a blood ves- interval between the injury and the start

sel ruptures into the cerebrospinal fluid of symptoms varies from days to months.

that surrounds the brain and spinal Diagnosis is by CT scanning or MRI. In

cord. It usually occurs spontaneously many cases, surgical treatment is need-

but may follow unaccustomed exercise. ed. This involves drilling burr holes in

It is most common in people between the skull (see craniotomy), so that the

35 and 60. The most common cause is a blood can be drained out and damaged

burst aneurysm (see berry aneurysm). blood vessels repaired. If treatment is

An attack may cause loss of conscious- carried out at an early enough stage,

ness, sometimes preceded by a sudden the person usually makes a full recov-

violent headache. If the person remains ery. A subdural haemorrhage that is

conscious, symptoms such as photo- small and produces few symptoms may

phobia, nausea, drowsiness, and stiffness not require any treatment. The affected

530

SUBLIMATION SUDECK’S ATROPHY

SUBDURAL HAEMORRHAGE dental). If the tooth’s blood vessels are
torn, root-canal treatment is required.
Skull Skull subluxation Incomplete dislocation of a
joint, in which the surfaces of the bones
Scalp remain in partial contact.
submucous resection An operation to
Brain correct a deviated nasal septum.
subphrenic abscess An abscess under
LOCATION the diaphragm.
substance abuse The use of drugs or
Arachnoid other substances for a purpose other
than that which is normally recommen-
Dura ded. Stimulant drugs, solvents, and
mater glue, are all commonly abused. Prob-
lems may arise due to adverse effects or
NORMAL from the habit-forming potential of the
substance. (See also drug abuse.)
Dura mater substrate A substance on which an
enzyme acts.
Skull sucking chest wound An open wound
Blood clot in the chest wall through which air pas-
compressing ses, causing the lung on that side to
brain and collapse. Severe breathlessness and a
arachnoid life-threatening lack of oxygen result.
sucralfate An ulcer-healing drug used
SUBDURAL HAEMORRHAGE to treat peptic ulcer. Possible side effects S
are constipation and abdominal pain.
person is usually monitored with regular suction The removal of unwanted fluid or
scans, and the clot may clear up on its semi-fluid material from the body with
own. (See also extradural haemorrhage.) a syringe and hollow needle or with an
sublimation In psychoanalytic theory, the intestinal tube and a mechanical pump.
unconscious process by which primitive, suction lipectomy A cosmetic proced-
unacceptable impulses are redirected in- ure, also called liposuction, that is used
to socially acceptable forms of behaviour. in body contour surgery.
sublingual A term meaning under the sudden death See death, sudden.
tongue. Drugs taken sublingually, either sudden infant death syndrome The
as tablets or spray, are rapidly absorbed sudden, unexpected death of an infant
into the bloodstream via the lining of that cannot be explained.
the mouth. For example, nitrate tablets
are given sublingually to provide rapid Possible risk factors include: laying
relief of an angina attack. the baby face-down to sleep; overheat-
subluxated tooth A tooth displaced in ing; parental smoking after the birth;
its socket as the result of an accident. prematurity and low birth weight; and
The upper front teeth are the most poor socioeconomic background.
vulnerable. A subluxated tooth can usu-
ally be manipulated back into position, Preventive measures include: ensuring
and is then immobilized (see splinting, that the baby sleeps on its back at the
foot of the cot; regulating the baby’s
temperature (using the same amount of
clothing and blankets that an adult
would need); and stopping smoking.
Sudeck’s atrophy Swelling and loss of
use of a hand or foot after a fracture or
other injury. Treatment includes eleva-
tion of the affected hand or foot, gentle
exercise, and heat treatment. Full recov-
ery is usual within about 4 months.

531

SUFFOCATION SUNTAN

suffocation A condition in which there sulphur A mineral that is a constituent of

is a lack of oxygen due to obstruction to vitamin B1 (see vitamin B complex) and
the passage of air into the lungs. (See several essential amino acids. In the body,

also asphyxia; choking; strangulation.) it is needed for the manufacture of col-

sugar See carbohydrates. lagen and is a constituent of keratin. It is

suicide The act of intentionally killing used in the form of a cream to treat acne.

oneself. Suicide results from a person’s sulpiride An antipsychotic drug used in

reaction to a perceivedly overwhelming the treatment of schizophrenia and

problem, such as social isolation, death Gilles de la Tourette’s syndrome.

of a loved one, serious physical illness, sumatriptan A serotonin agonist drug

or financial problems. It is often the re- that relieves acute attacks of migraine,

sult of a psychiatric illness, such as severe especially those that have not responded

depression or schizophrenia. to analgesics; it is particularly effective

Suicide is most common among the in treating cluster headaches. Sumatrip-

elderly. More men than women commit tan may cause chest pain and tightness,

suicide, although women attempt the flushing, dizziness, and weakness.

act more often (see suicide, attempted). sunburn Inflammation of the skin caused

The most common method is poisoning, by overexposure to the sun. The ultra-

usually by taking a drug overdose or by violet light in sunlight may destroy cells

inhaling car exhaust fumes. in the outer layer of the skin and dam-

suicide, attempted Any deliberate act age tiny blood vessels beneath.

of self-harm that is or is believed to be Fair-skinned people are most suscep-

life-threatening but that in effect proves tible. The affected skin turns red and

nonfatal. Attempted suicide is more tender and may become blistered. The

common in women and most common dead skin cells are later shed by peeling.

in the 15–30 age group. The rate is high- Calamine lotion soothes the burned

est in people with personality disorders skin. Analgesic drugs may be taken to

and in those who live in deprived urban relieve discomfort. A high protection fac-

areas or have alcohol or drug problems. tor sunscreen helps to prevent sunburn.

Common precipitating factors include Severe sunburn in childhood increases

the death of a loved one, financial wor- the risk of skin cancer in later life.

ries, or severe loss of any kind that sunlight, adverse effects of Problems

results in depression. The most common resulting from overexposure to sunlight.

method is drug overdose. Fair-skinned people are more suscepti-

Urgent treatment is needed for drug ble. Short-term overexposure causes

poisoning. Longer-term therapy aims to sunburn and, in intense heat, can result

provide support and treat depression. in heat exhaustion or heatstroke. Repeat-

sulfasalazine A drug used to relieve ed overexposure over a long period can

S inflammation in Crohn’s disease and cause premature aging of the skin and
ulcerative colitis. It may cause nausea, solar keratoses. It increases the risk of

headache, fever, and loss of appetite. skin cancer. Protection of the skin with

sulfinpyrazone A drug that reduces the sunscreens helps to prevent sun damage.

frequency of attacks of gout. Side effects Photosensitivity is an abnormal sensitiv-

include nausea and abdominal pain. ity to sunlight, resulting in a rash.

sulindac A nonsteroidal anti-inflamma- Exposure to sunlight can affect the

tory drug (NSAID) used to relieve joint eyes, causing irritation of the conjunctiva,

pain and stiffness in various types of arth- actinic keratopathy, or pterygium. Good

ritis and acute gout. Side effects are as sunglasses help to prevent eye problems.

for other NSAIDs. sunscreens Preparations that help to

sulphasalazine See sulfasalazine. protect the skin from the harmful effects

sulphinpyrazone See sulfinpyrazone. of sunlight.

sulphonamide drugs A group of anti- sunstroke A common form of heatstroke.

bacterial drugs that has largely been suntan Darkening of the skin after expo-

superseded by more effective and less sure to sunlight. Specialized cells in the

toxic alternatives. epidermis respond to ultraviolet light by

532

SUPEREGO SUTURE

producing the pigment melanin. (See occurs in episodes lasting for several S
also sunlight, adverse effects of; sunburn.) hours or days. Supraventricular tachy-
superego The part of the personality, cardia occurs when abnormal electrical
as described in psychoanalytic theory, impulses that arise in the atria of the
that is responsible for maintaining a heart take control of the heartbeat from
person’s standards of behaviour. Popu- the sinoatrial node. Symptoms include
larly termed the “conscience”, the palpitations, breathlessness, chest pain,
superego arises as a result of a child or fainting (see Stokes–Adams syndrome).
incorporating the moral views of those
in authority (usually parents). Diagnosis is by an ECG. An attack can
superficial Situated near the surface. sometimes be terminated by Valsalva’s
superinfection A second infection that manoeuvre or by drinking cold water.
occurs during the course of an existing Recurrent attacks are treated with anti-
infection. The term usually refers to an arrhythmic drugs. Rarely, the condition
infection by a microorganism that is may require application of an electric
resistant to drugs being used against shock to the heart (see defibrillation).
the original infection. surfactant A substance, such as a soap
superiority complex An individual’s or emulsifier, that reduces surface ten-
exaggerated and unrealistic belief that sion. Pulmonary surfactant is secreted by
he or she is better than other people. In the alveoli in the lungs, preventing them
modern psychoanalytic theory, a superi- from collapsing during exhalation, and
ority complex is considered to be a is absent in babies born significantly
compensation for unconscious feelings prematurely. This deficiency causes
of inadequacy or low self-esteem. breathing difficulties, and the infant
supernumerary A term meaning more needs artificial ventilation and the admin-
than the normal number. istration of an artificial surfactant.
supernumerary teeth One or more surfer’s nodules Multiple bony out-
teeth in excess of the usual number. growths on the foot bones and on the
These teeth are usually extracted. bony prominence just below the knee.
supination The act of turning the body surgery The treatment of disease, injury,
to a supine position (lying on the back or other disorders by direct physical inter-
with the face upward) or of turning the vention, or those aspects of medicine that
hand to a palm forward position. The deal with the study, diagnosis, and man-
opposite of supination is pronation. agement of disorders treated in this way.
suppository A solid medical prepara- surgical spirit A liquid preparation,
tion, of cone or bullet shape, designed consisting mainly of ethyl alcohol, that
to be placed in the rectum to dissolve. has a soothing and hardening effect
Suppositories are used to treat rectal when applied to the skin. It may be
disorders such as haemorrhoids or used before injections as an antiseptic.
proctitis. They may also be used to soft- surrogacy The agreement by a woman
en faeces and stimulate defaecation. In to become pregnant and give birth to a
addition, suppositories may be used to child with the understanding that she
administer drugs into the general circu- will surrender the child after birth to the
lation, via blood vessels in the rectum, if contractual parents. Surrogacy may be
vomiting is likely to prevent absorption accomplished by artificial insemination
after oral administration or if the drug or by in vitro fertilization.
would cause irritation of the stomach. susceptibility A total or partial vulner-
suppuration The formation or discharge ability to an infection or disorder.
of pus. suture A type of joint, found only be-
suprarenal glands Another name for tween the bones of the skull, in which the
the adrenal glands. adjacent bones are mobile during birth
supraspinatus syndrome See painful but then become so closely and firmly
arc syndrome. joined by a layer of connective tissue that
supraventricular tachycardia An ab- movement between them is impossible.
normally fast but regular heart-rate that
The term suture is also used to refer
to a surgical stitch (see suturing).

533

SUTURING SWEAT GLANDS

SUTURING the stomach via the oesophagus. Once
food has been chewed and mixed with

saliva to form a bolus, the tongue push-
Skin es the bolus to the back of the mouth

and the voluntary muscles in the palate

push it into the throat. The rest of the

Wound swallowing process occurs by a series of

reflexes. Entry of food into the throat

Stitch causes the epiglottis to tilt down to seal
the trachea and the soft palate to move

back in order to close off the naval cavi-

SUBCUTICULAR STITCH ty. The throat muscles push the food
into the oesophagus. Waves of contrac-

Skin tion (peristalsis) along the oesophagus
propel the food towards the stomach.

Wound swallowing difficulty A common symp-
tom with various possible causes,

Stitch including a foreign object in the throat;
insufficient production of saliva (see

mouth, dry); a disorder of the oesophagus

such as oesophageal stricture; pressure

on the oesophagus, for example from a

INTERRUPTED STITCHES goitre; a nervous system disorder such as
myasthenia gravis or stroke; or a psycho-

logical problem such as globus hystericus.

suturing The closing of a surgical inci- Investigations of swallowing difficulty

sion or a wound by sutures (stitches) to may include oesophagoscopy or barium

promote healing. This may be done by swallow (see barium X-ray examinations).

means of a single stitch under the skin Treatment depends on the cause.

(subcuticular) or by using individual swamp fever Another name for lepto-

stitches (interrupted). Some materials spirosis. The term is also sometimes

used in suturing, such as catgut, eventu- applied to malaria.

ally dissolve in the body; skin sutures sweat glands Structures deep within the

made of other materials are removed skin that produce sweat, which is mainly

about 1–2 weeks after insertion. water with some dissolved substances,

swab A wad of absorbent material used including salt. There are 2 types of sweat

to apply antiseptics or soak up body flu- glands: eccrine glands, which are most

ids during surgery, or to obtain a sample numerous and open directly on to the

S of bacteria from an infected patient. skin surface, and apocrine glands, which
swallowing The process by which food develop at puberty. Apocrine glands,

or liquid is conveyed from the mouth to which open into a hair follicle, occur only

Soft palate SWALLOWING
Food bolus
Tongue Soft palate
moved back

Bolus

Epiglottis in Tilted
raised position epiglottis

Oesophagus Trachea sealed
Trachea Oesophagus

FOOD IN MOUTH FOOD IN THROAT

534

SWEATING S Y N D A C T Y LY

SWEAT GLANDS sympathectomy An operation in which S
the ganglia (nerve terminals) of sympa-
Hair Sweat droplet thetic nerves are destroyed to interrupt
the nerve pathway. This may be per-
Sweat formed to improve blood supply to a
gland limb (as a treatment for peripheral vas-
cular disease) or to relieve chronic pain,
ECCRINE SWEAT GLAND IN SKIN for example causalgia.

in hairy areas, particularly the armpits, sympathetic nervous system One of
pubic region, and around the anus. the 2 divisions of the autonomic nervous
system. In conjunction with the other
The sweat glands are controlled by the division (the parasympathetic nervous
autonomic nervous system. The glands system), this system controls many of
are usually stimulated to keep the body the involuntary activities of the body’s
cool, but anxiety or fear can also cause glands and organs.
sweating. Sweat is odourless until bac-
teria act upon it, producing body odour. symphysis A type of joint in which 2
bones are firmly joined by tough carti-
A common disorder of the sweat lage. Such joints occur between the
glands is prickly heat. Other disorders vertebrae; between the pubic bones at
include hyperhidrosis and hypohidrosis. the front of the pelvis; and between the
sweating The process by which the body upper and middle parts of the sternum.
cools itself. (See also sweat glands.)
sweeteners, artificial See artificial symptom An indication of a disease or
sweeteners. disorder that is noticed by the sufferer.
swimmer’s ear A common name for By contrast, the indications that a doc-
otitis externa. tor notes are called signs.
sycosis barbae Inflammation of the
beard area due to infection of the hair symptothermal method See contra-
follicles, usually with STAPHYLOCOCCUS ception, natural methods of.
AUREUS bacteria contracted from in-
fected razors or towels. Pus-filled synaesthesia A condition in which stim-
blisters appear around the follicles. Treat- ulation of one of the senses (by a sound,
ment is usually with antibiotic drugs. for example) produces an additional
Sydenham’s chorea A rare childhood response, such as the appearance of a
disorder of the central nervous system colour in addition to the normal per-
that causes involuntary jerky movements ception associated with that stimulus.
of the head, face, limbs, and fingers. Vol-
untary movements are clumsy, and the synapse A junction between 2 neurons
limbs become floppy. The disorder usu- across which a signal can pass. At a
ally follows an attack of rheumatic fever. synapse, the 2 neurons do not come
directly into contact but are separated
Sydenham’s chorea usually clears up by a gap called the synaptic cleft. When
after 2–3 months and has no long-term an electrical signal passing along a neu-
adverse effects. ron reaches a synapse, it causes the
release of a chemical called a neuro-
transmitter. The neurotransmitter travels
across the synaptic cleft to the surface
membrane of the next neuron, where it
changes the electrical potential of the
membrane. Signals can be transmitted
across a synapse in one direction only.
Most drugs affecting the nervous sys-
tem work as a result of their effects on
synapses. Such drugs may affect the
release of neurotransmitters, or they
may modify their effects.

syncope The medical term for fainting.
syndactyly A congenital defect in which

2 or more fingers or toes are joined.

535

SYNDROME SYPHILIS, NONVENEREAL

Syndactyly is often inherited and is more The synovium also forms a sheath for

common in males. In mild cases, the certain tendons of the hands and feet.

affected fingers or toes are joined only The membrane secretes synovial fluid,

by a web of skin. In more serious cases, which lubricates the joint or tendon. The

the bones of adjacent digits are fused. synovium can become inflamed; in a

Surgery to separate the affected digits joint this is known as synovitis, in a ten-

may be performed in early childhood. don sheath it is known as tenosynovitis.

syndrome A group of symptoms and/or syphilis An infection caused by TREPON-

signs that, occurring together, consti- EMA PALLIDUM bacteria and spread

tutes a particular disorder. through sexual intercourse or other inti-

synovectomy Surgical removal of the mate body contact, or, less commonly,

membrane lining a joint capsule to treat from mother to fetus during pregnancy.

recurrent or persistent synovitis, usually Following sexual infection, the organ-

due to severe rheumatoid arthritis. ism spreads rapidly via the bloodstream

synovitis Inflammation of the membrane and lymphatic system. The first symptom

lining a joint capsule. The condition is a sore (chancre) that appears on the

may be acute, in which case it is usually genitals, anus, rectum, lips, throat, or

caused by an attack of arthritis, injury, fingers and heals in 4–8 weeks. A rash

or infection; or chronic, as in a disorder then develops, which may be transient,

such as rheumatoid arthritis. The affec- recurrent, or may last for months. Other

ted joint becomes swollen, painful, and possible symptoms include lymph node

often warm and red. To find the cause, enlargement, headache, bone pain, loss

joint aspiration or biopsy may be needed. of appetite, fever, and fatigue. Thickened,

Symptoms are relieved by rest, sup- grey or pink patches may develop on

porting the joint with a splint or cast, moist areas of skin and are highly infec-

analgesics, nonsteroidal anti-inflammatory tious. Meningitis may also develop.

drugs, and, occasionally, a corticosteroid Following this symptomatic phase, the

injection. Chronic synovitis may be trea- disease becomes latent for a few years,

ted by synovectomy. or sometimes indefinitely. A few untrea-

synovium A membrane that lines the ted cases proceed, eventually, to a final

capsule surrounding a movable joint. stage characterized by widespread tissue

SYNOVIUM destruction. This may be accompanied
by cardiovascular syphilis, which affects

the aorta and leads to aneurysm and

heart-valve disease; neurosyphilis, with

Bone progressive brain damage and paralysis;

and tabes dorsalis of the spinal cord.

Signs of congenital infection include a

S rash, persistent snuffles, bone abnorma-
lities, jaundice, and enlargement of the

Synovium liver and spleen. Keratitis, arthritis, a
characteristic flat face, peg-shaped teeth,

and mental handicap may appear later

Articular in childhood.
cartilage Diagnosis is by examination of chancre

serum or by blood tests. All forms of

Synovial syphilis are treated with antibacterial
fluid drugs. Organ damage already caused by
the disease cannot be reversed.

Practising safer sex can help to prevent

Ligament syphilis infection. People with syphilis

are infectious in the early stages but

not in the latent and final stages.

syphilis, nonvenereal An infection due

TYPICAL JOINT to TREPONEMA PALLIDUM bacteria that is

536

SYRINGE SYSTOLE

spread by nonsexual means, such as joints. The condition is 3 times as com-
through broken skin or saliva. It occurs mon in women and is most likely to
mainly in the Middle East and Africa. appear between the age of 30 and 50.
Treatment is with antibacterial drugs.
syringe An instrument that is commonly The number and severity of symptoms
used with a needle for injecting fluid varies. The most common symptom is
into, or withdrawing fluid from, a body Raynaud’s phenomenon. Also common
cavity, blood vessel, or tissue. are changes in the skin, especially of the
syringe driver A portable device used face and fingers, which becomes shiny,
to provide continuous pain relief in tight, and thickened, leading to difficulty
conditions such as cancer. The syringe with movements. Other parts of the body
driver delivers a certain amount of an may also be affected, leading to difficulty
analgesic (painkiller) over a set period in swallowing, shortness of breath, palpi-
of time. It is attached to a syringe, tations, high blood pressure, joint pain,
which pumps the drug, via a tube, or muscle weakness. Progression of scle-
through a needle inserted into the skin. roderma is often rapid in the first few
syringing of ears The flushing out of years and then slows down or even stops.
excess earwax or a foreign body from In a minority of people, degeneration is
the outer ear canal by introducing water rapid, and leads to death from heart fail-
from a syringe into the ear canal. ure, respiratory failure, or kidney failure.
syringomyelia A rare, progressive con-
dition, usually congenital, in which a There is no cure for scleroderma, but
cavity forms in the brainstem or in the many of the symptoms can be relieved.
spinal cord at neck level and gradually systole A period of muscular contraction
expands, filling with cerebrospinal fluid. of a chamber of the heart that alternates
Symptoms usually appear in early adult- with a resting period known as diastole.
hood and include lack of temperature or
pain sensation, wasting of muscles in the S
neck, shoulders, arms, and hands, and
some loss of the sense of touch. Later,
there is difficulty in moving the legs and
controlling the bladder and bowel.

There is no drug treatment. Surgery can
relieve pressure in the central cavity to
prevent further enlargement, or alterna-
tively, decompress the distended spinal
cord (see decompression, spinal canal).
system A group of interconnected or
interdependent organs with a common
function, as in the digestive system.
systemic A term applied to something
that affects the whole body rather than a
specific part of it. For example, fever is
a systemic symptom, whereas swelling
is a localized symptom. The term sys-
temic is also applied to the part of the
blood circulation that supplies all parts
of the body except the lungs.
systemic lupus erythematosus See
lupus erythematosus.
systemic sclerosis Also known as scle-
roderma, a rare autoimmune disorder
that can affect many organs and tissues,
particularly the skin, arteries, kidneys,
lungs, heart, gastrointestinal tract, and

537

TABES DORSALIS TARDIVE DYSKINESIA

T of infertility. It may cause nausea, vomit-
ing, hot flushes, swollen ankles, and
irregular vaginal bleeding.
tampon A plug of absorbent material
inserted into a wound or body opening to
soak up blood or other secretions. The

term commonly refers to a vaginal tam-

pon, used to absorb menstrual blood.

tamponade Compression of the heart by

tabes dorsalis A rare complication of fluid within the pericardium, which may

untreated syphilis that appears years after cause breathlessness and collapse. Caus-

infection. The condition causes abnor- es include pericarditis, complications after

malities of sensation, sharp pains, heart surgery, or a chest injury. A diag-

incoordination, and incontinence. nosis is made by echocardiography, and

tachycardia An adult heart rate of over the fluid is removed through a needle.

100 beats per minute. The average heart tamsulosin An alpha-blocker drug used

rate is 72–78 beats per minute. Tachy- for the treatment of urinary symptoms

cardia occurs in healthy people during due to an enlarged prostate gland (see

exercise. At rest, it may be due to fever, prostate, enlarged). Side effects include

anxiety, hyperthyroidism, coronary artery low blood pressure, drowsiness, dry

disease, high caffeine intake, or treatment mouth, and gastrointestinal disturbances.

involving anticholinergic or diuretic drugs. tan See suntan.

There are various types of tachycardia, tannin Also known as tannic acid, a

which originate in different areas of the chemical that occurs in many plants, par-

heart; the types include atrial fibrillation, ticularly tea. It may cause constipation,

sinus tachycardia, supraventricular tachy- and large amounts cause liver damage.

cardia, and ventricular tachycardia. tantrum An outburst of bad behaviour,

tachypnoea An abnormally fast rate of common in toddlers, usually indicating

breathing, which may be caused by exer- frustration and anger.

cise, anxiety, or lung or cardiac disorders. tapeworm infestation Tapeworms (ces-

T’ai chi A Chinese exercise system based todes) are ribbon-shaped worms that

on a series of over 100 postures between infest the intestines of humans and ani-

which slow, continuous movements are mals. They are usually acquired by

made. The aim is to exercise the muscles eating undercooked meat or fish. Tape-

and integrate mind and body. worms from beef, pork, and fish usually

talipes A birth defect (commonly called only cause mild abdominal discomfort

club-foot) in which the foot is twisted or diarrhoea. However, if eggs of pork

out of shape or position. The cause may worms are ingested, the hatched larvae

be pressure on the feet from the mother’s burrow into tissues to form cysts. This

uterus, or a genetic factor. The most leads to cysticerosis, the symptoms of

T common form is an equinovarus defor- which are muscle pain and convulsions.
mity, in which the heel turns inwards Rarely, fish tapeworms cause anaemia.

and the rest of the foot bends down and Dwarf tapeworms, common in the trop-

inwards. It is treated by repeated ics, can cause diarrhoea and abdominal

manipulation of the foot and ankle, discomfort. Tapeworms acquired from

starting soon after birth. A plaster cast, dogs cause hydatid disease. A diagnosis

splint, or strapping may be used to hold is made from the presence of worm seg-

the foot in position. If this is not suc- ments or eggs in the faeces. Treatment

cessful, surgery will be needed. is with anthelmintic drugs.

talus The square-shaped foot bone that tardive dyskinesia Abnormal, uncon-

forms the ankle joint together with the trolled movements, mainly of the face,

tibia and fibula. tongue, mouth, and neck. Tardive dyski-

tamoxifen An anticancer drug that is nesia may be caused by prolonged use

used to treat certain forms of breast can- of antipsychotic drugs, and is distinct

cer, and, sometimes, to treat some types from parkinsonism.

538

TARSALGIA TECHNETIUM

tarsalgia Pain in the rear part of the foot, buds from stomatitis, mouth cancer, or

usually associated with flat-feet. radiotherapy to the mouth; or damage

tarsorrhaphy Surgery in which the upper to nerves that carry taste sensations.

and lower eyelids are partially or com- tattooing The introduction of permanent

pletely sewn together. Tarsorrhaphy may colours under the skin surface, usually to

be used as part of the treatment of create a picture. Small tattoos can be

corneal ulcer, or to protect the corneas removed by cutting out the tattoo and

of people who cannot close their eyes or stitching the wound edges together. Lar-

those with exophthalmos. The eyelids ger tattoos can sometimes be removed

are later cut apart and allowed to open. by dermabrasion or by laser treatment.

tarsus The 7 bones that make up the taxanes A group of anticancer drugs used

back of the foot and the ankle. to treat certain cancers, such as ovarian

tartar See calculus, dental. cancer (see ovary, cancer of) and breast

taste One of the 5 senses. Taste can dis- cancer. They work by preventing the

tinguish only between sweet, salt, sour, growth of cancer cells. Common taxane

and bitter, but in combination with the drugs include paclitaxel and docetaxel.

sense of smell, many different flavours Tay–Sachs disease A serious inherited

can be distinguished. Tastes are detect- metabolic disorder (see metabolism, in-

ed by structures called taste buds. born errors of) that causes premature

taste bud One of 10,000 specialized death. The cause is deficiency of the

structures located mainly on the tongue, enzyme hexosaminidase A, which results

with some at the back of the throat and on in a buildup in the brain of a harmful

the palate. Each bud contains about 25 substance. Symptoms usually appear af-

sensory receptor cells, with tiny taste hairs ter age 6 months and include blindness,

that respond to food and drink. Taste buds paralysis, and seizures leading to death.

on different parts of the tongue sense the Diagnosis is made by enzyme analysis of

4 basic tastes: bitter, sour, salty, and sweet. white blood cells. It is now largely pre-

TASTE BUD vented by genetic
counselling of high-

Tongue Taste hair Surface cell on tongue risk groups.
TB An abbreviation

for tuberculosis.

T-cell A class of

lymphocyte.

tears The watery,

salty secretion that

is produced by the

lacrimal glands, part

LOCATION of the lacrimal ap-

paratus of the eye.

Receptor cell Tears keep the cor- T

Supporting cell nea and conjunctiva
moist to maintain

Nerve fibre transparency of the
cornea and prevent

ulcers; aid blinking;

and wash away for-

taste, loss of Loss of the sense of taste, eign particles. Tear production increases

usually as a result of the loss of the in response to eye irritation and emotion.

sense of smell. The most common cause tears, artificial Preparations to supple-

is inflammation of the nasal passages. ment tear production in disorders that

Other causes of loss of taste include cause dry eye, such as keratoconjunctivitis

any condition that causes a dry mouth sicca, and to relieve irritation.

(see mouth, dry); natural degeneration technetium A radioactive element used

of the taste buds; damage to the taste in radionuclide scanning.

539

TEETH TEETH TEMPORAL ARTERITIS

Crown Enamel and a “broken veins” appearance. It is
Root most common on the nose and cheeks.
Dentine There may be no obvious cause, or the
condition may be due to many years of
Gum excessive alcohol consumption, rosacea,
(gingiva) overexposure to sunlight, or a connective
tissue disease such as dermatomyositis.
Pulp
Telangiectasia is not a cause for con-
Periodontal cern, but the veins can be removed in
ligament some cases by electrodesiccation (elec-
trical destruction of the upper layers of
Cementum the skin). (See also spider naevus.)
temazepam A benzodiazepine drug that
Jawbone is used to treat insomnia and also as a
drug of abuse.
Nerve temperature The degree of hotness of a
body or substance. In the human body,
Blood the temperature must be maintained at
vessel around 37°C for optimum functioning.
STRUCTURE OF A TOOTH Body temperature is maintained by the
hypothalamus, which monitors blood
teeth Hard, bone-like projections set in temperature and activates mechanisms
the jaws and surrounded by the gums. to compensate for changes. When body
The teeth are used for mastication, help temperature falls, shivering creates heat
to form speech, and give shape to the by muscle activity, and constriction of
face. At the centre of each tooth is the blood vessels in the skin minimizes
pulp, which contains blood vessels and heat loss. When the body temperature
nerves and is surrounded by hard den- rises, sweating results in cooling, and
tine. The part of the tooth above the dilation of blood vessels in the skin
gum, the crown, is covered by enamel, increases heat loss.
the hardest substance in the body. temperature method See contracep-
The roots of the tooth, which fit into the tion, natural methods of.
jawbone, are covered by bone-like temporal A medical term meaning of or
cementum. Humans have 32 permanent near the temples or a temple.
teeth, which erupt after the primary temporal arteritis An uncommon dis-
teeth are lost. These teeth comprise ease of older people in which the walls of
the arteries in the scalp over the temples
T chisel-shaped, biting incisors; sharp, become inflamed. Other arteries in the
pointed canines; grinding premolars; body may also be affected. The cause is
and larger grinding molars. unknown, but the condition is often
teeth, care of See oral hygiene. associated with polymyalgia rheumatica.
teething The period when a baby cuts Symptoms may include severe headache
his or her primary teeth (see eruption of on 1 or both sides, scalp tenderness, a
teeth). While teething, a baby may be low fever, and poor appetite. In about
irritable, fretful, clingy, have difficulty half of the cases, the arteries supplying
sleeping, and may cry more than usual. the eyes are affected, which may cause
Symptoms may be relieved by the use sudden blindness if left untreated.
of painkilling gels that are rubbed on
the gums, or liquid preparations. Diagnosis of temporal arteritis is made
telangiectasia An increase in the size by blood tests (including ESR) and, in
of small blood vessels beneath the sur- some cases, by a biopsy of the temporal
face of an area of skin, causing redness artery. Treatment involves the use of a
corticosteroid drug. If this is not suc-
cessful, immunosuppressants may be
given. The disease usually clears up
within 2 years.

540

TEMPORAL LOBE EPILEPSY TENESMUS

temporal lobe epilepsy A form of tendon A fibrous cord that joins muscle T
epilepsy in which abnormal electrical dis- to bone or muscle to muscle. Tendons
charges occur in the temporal lobe (most are strong and flexible, but inelastic.
of the lower side of each half of the cere- Those in the hands, wrists, and feet are
brum) in the brain. The usual cause is enclosed in synovial sheaths (fibrous
damage to the temporal lobe, which capsules) that secrete a lubricating fluid.
may be due to a birth injury, head injury,
brain tumour, brain abscess, or stroke. TENDON
Attacks of this form of epilepsy cause
dreamlike states, unpleasant hallucina- Tendon
tions of smell or taste, the perception of
an illusory scene, or déja vu. There may Bone
also be grimacing, rotation of the head
and eyes, and sucking and chewing Muscle
movements. The affected person may
have no memory of activities during an Tendon
attack, which can last for minutes or
hours. Sometimes, the seizure develops tendon release See tendolysis.
into a grand mal seizure. Diagnosis and tendon repair Surgery to join the cut
drug treatment is the same as for other
forms of epilepsy. or torn ends of, or to replace, a tendon.
tendon rupture A complete tear in a
temporomandibular joint The joint
between the mandible (lower jaw bone) tendon. A tendon may rupture when the
and the skull. muscle to which it is attached contracts
suddenly and powerfully, such as during
temporomandibular joint syndrome vigorous exercise. Rupture may also be
Pain and other symptoms affecting the due to an injury or joint disorder such
head, jaw, and face, thought to result as rheumatoid arthritis. Symptoms
when the temporomandibular joints and include a snapping sensation, impaired
the muscles and ligaments attached to movement, pain, and swelling. Diagnosis
them do not work together correctly. is usually obvious from the symptoms.
Causes include spasm of the chewing Surgery to repair the tendon may be
muscles, an incorrect bite (see maloc- needed. In some cases, the tendon may
clusion), jaw, head, or neck injuries, or heal if immobilized in a plaster cast.
osteoarthritis. Common symptoms include tendon transfer Surgery to reposition
headaches, tenderness of the jaw mus- a tendon so that it makes a muscle per-
cles, and aching facial pain. Treatment form a different function. The tendon is
involves correction of any underlying cut from its original point of attachment
abnormality, analgesic drugs, and, in and reattached elsewhere, making the
some cases, injection of corticosteroid muscle lie in a different position. The
drugs into the joint. procedure may be used to treat talipes
or permanent muscle injury or paralysis.
tenderness Pain or abnormal sensitivity tenesmus A feeling of incomplete empty-
in a part of the body when it is pressed ing of the bowel in which an urge to pass
or touched. faeces accompanies ineffective straining.
It may be a symptom of inflammation
tendinitis Inflammation of a tendon, or of a tumour (see colon, cancer of).
usually caused by injury or overuse.
Symptoms of tendinitis include pain,
tenderness, and restricted movement.
Treatment is with nonsteroidal anti-
inflammatory drugs (NSAIDs), ultrasound
treatment, or injection of a corticosteroid
drug around the tendon.

tendolysis An operation performed to
free a tendon from adhesions that limit
its movement. The adhesions are usu-
ally caused by tenosynovitis.

541

TENNIS ELBOW TESTICULAR FEMINIZATION

tennis elbow Pain and tenderness on area of the pain. TENS can help relieve

the outside of the elbow and in the back chronic pain not controlled by analgesic

of the forearm. Commonly called epicon- drugs and may be used in childbirth.

dylitis, it is caused by inflammation of tension A feeling of mental and physical

the tendon that attaches the muscles strain associated with anxiety. Muscle

that straighten the fingers and wrist to the tension may cause headaches and stiff-

humerus. Treatment consists of resting ness in muscles. Persistent tension is

the arm, applying ice-packs, and taking related to generalized anxiety disorder.

analgesic drugs or nonsteroidal anti- (See also stress.)

inflammatory drugs (NSAIDs). Ultrasound teratogen A physical, chemical, or bio-

treatment, injection of a corticosteroid logical agent, such as radiation, the

drug, or surgery are sometimes needed. drug thalidomide, and the rubella virus,

tenosynovitis Inflammation of the lin- that causes abnormalities in a develop-

ing of the sheath that surrounds a ing embryo or fetus.

tendon. The usual cause is excessive fric- teratoma A primary tumour consisting

tion caused by repetitive movements; of cells totally unlike those normally

bacterial infection is a rare cause. The found in that part of the body.

hands and wrists are most often affect- terbinafine An antifungal drug used to

ed. Symptoms include pain, tenderness, treat fungal nail or skin infections. Side

and swelling over the tendon. Treatment effects are rare with topical use but may

is with nonsteroidal anti-inflammatory include local irritation. Taken as tablets,

drugs (NSAIDs) or a local injection of a the drug may cause nausea, abdominal

corticosteroid drug. However, if infection pain, and, occasionally a rash.

is the cause, antibiotic drugs are pre- terbutaline A bronchodilator drug used

scribed. A splint to immobilize the joint, to treat asthma and chronic obstructive

or surgery, may also be needed. pulmonary disease, and also to prevent

tenovaginitis Inflammation or thicken- premature labour. Possible adverse ef-

ing of the fibrous wall of the sheath that fects include nervousness, restlessness,

surrounds a tendon. tremor, nausea, and palpitations.

TENS Abbreviation for transcutaneous terminal care See dying, care of the.

electrical nerve stimulation, a method termination of pregnancy See abor-

of pain relief. Minute electrical impulses, tion, induced.

which block pain messages to the brain, testicle See testis.

are relayed from an impulse generator testicular feminization syndrome A

to electrodes attached to the skin in the rare inherited condition in which a gen-

TENS etic male with internal testes has the
external appearance of a female. The syn-

drome is a form of intersex and is the

most common form of male pseudoher-

maphroditism. The cause is a defective

T Electrode response of the body tissues to testos-
terone. The causative genes are carried

Impulse on the X chromosome, and so females

generator can be carriers. Affected individuals ap-

pear to be girls throughout childhood,

and most develop female secondary

sexual characteristics at puberty; but

amenorrhoea occurs, and a diagnosis is

usually made during investigations to

find its cause. Chromosome analysis

shows the presence of male chromo-

somes and blood tests show male levels

of testosterone. Treatment of testicular

feminization syndrome involves surgi-

cal removal of the testes, to prevent

542

TESTIS TESTIS, TORSION OF

cancerous change in later life, and ther- testis, ectopic A testis that is absent

apy with oestrogen drugs. An affected from the scrotum because it has descen-

person is not fertile but can live a nor- ded into an abnormal position, usually

mal life as a woman. in the groin or at the base of the penis.

testis One of 2 male sexual organs, also The condition is most often discovered

called testicles, that produce sperm and soon after birth during a routine physical

the hormone testosterone. The testes examination. It is treated by orchidopexy.

develop in the fetus within the abdomen (See also testis, undescended.)

and usually descend into the scrotum testis, pain in the Pain in a testis may

by birth or within the next few months. be caused by mild injury, a tear in the

Each testis contains seminiferous tubu- wall of the testis due to a direct blow,

les that produce sperm. Cells between orchitis, epididymo-orchitis, and torsion

the seminiferous tubules produce testos- of the testis (see testis, torsion of). Some-

terone. Each testis is suspended by the times, no cause is found and the pain

spermatic cord, composed of the vas def- disappears without treatment. If the wall

erens, blood vessels, and nerves. (See of the testis is torn, an operation to

also testis, undescended.) repair it may be needed.

TESTIS testis, retractile A
testis that is drawn up

Urethra Bladder Vas Spermatic high into the groin by
deferens cord a pronounced muscle
reflex in response to

Vas cold or touch. A retrac-
deferens tile testis is normal in
young children, but it

usually disappears by

Scrotum puberty.
testis, swollen Swel-

ling of the testis or the

surrounding tissues in

the scrotum. Harmless

and painless swellings

Penis Testis Epididymis include epididymal cysts,
hydroceles, varicoceles,
LOCATION Epididymis and spermatoceles. Can-

Seminiferous cer of the testis (see
tubule testis, cancer of) is rare
but may be a cause of
STRUCTURE OF A TESTIS

painless swelling. Swel-

testis, cancer of A rare, cancerous ling that is painful may be caused by a

tumour of the testis. Testicular cancer is direct blow, torsion of the testis (see T

most common in young to middle-aged testis, torsion of), orchitis, epididymo-

men, and the risk increases in indi- orchitis, or, in very rare cases, cancer of

viduals with a history of undescended the testis. Any swelling of the testes

testis (see testis, undescended). The should be assessed promptly by a doctor.

most common types of testicular cancer testis, torsion of Twisting of the sper-

are seminomas, which are made up of matic cord that causes severe pain and

only 1 type of cell, and teratomas. The swelling of the testis. The pain develops

cancer usually appears as a firm, pain- rapidly and is sometimes accompanied

less swelling of 1 testis. There may also by abdominal pain and nausea. The tes-

be pain and inflammation. Biopsy, fol- tis becomes swollen and very tender,

lowed by orchidectomy, is the usual and the skin of the scrotum becomes

treatment, and may be combined with discoloured. Unless the torsion is treated

chemotherapy. The tumours usually within a few hours, permanent damage

respond well to treatment. to the testis results. The condition is

543

TESTIS, UNDESCENDED TETANUS

TESTIS, TORSION OF gastric fluid is sucked up through the
tube. An injection of histamine or, more

Twisted usually, pentagastrin (a synthetic prepa-

spermatic ration of the hormone gastrin) is given;
cord further samples of stomach fluid are

taken at intervals for up to 2 hours and

Vas analysed for hydrochloric acid content.
deferens The test is used for people thought to

Blood be suffering from Zollinger–Ellison syn-
vessels drome, and to confirm the absence of

Penis stomach acid in people with pernicious
anaemia (see anaemia, pernicious).

testosterone The main androgen hor-

mone (male sex hormone). It stimulates

Testis Scrotum bone and muscle growth and sexual
twisted development. It is produced by the testes
around and, in very small amounts, the ovaries.

Synthetic or animal testosterone is

most common around puberty. It is used to stimulate delayed puberty or

more likely to occur if the testis is treat some forms of male infertility.

unusually mobile within the scrotum. tests, medical Tests may be performed

Diagnosis is by physical examination. to investigate the cause of symptoms

Surgery is performed to untwist the testis and establish a diagnosis, to monitor

and anchor it in the scrotum with small the course of a disease, or to assess

stitches to prevent recurrence. If irrever- response to treatment. A medical test-

sible damage has occurred, orchidectomy ing programme carried out on apparently

is performed. In either case, the other tes- healthy people to find disease at an early

tis is anchored to the scrotum to prevent stage is known as screening.

torsion on that side. With prompt treat- The accuracy of a test is based on its

ment, recovery of the testis is complete. sensitivity (ability to correctly identify

testis, undescended A testis that has diseased subjects), specificity (ability to

failed to descend from the abdomen to correctly identify healthy subjects), and

the scrotum. The condition usually affects predictive value. The predictive value is

only 1 testis and occurs in about 1 per determined by a mathematical formula

cent of full-term and 10 per cent of pre- that involves the number of accurate

mature male babies. An undescended test results and the total number of tests

testis often descends within months of performed. The best tests have both

birth but rarely descends after this time. high specificity and high sensitivity, and

An undescended testis does not de- therefore high predictive value.

velop normally, is incapable of normal tetanus A serious, sometimes fatal, dis-

T sperm production, and is at increased ease of the central nervous system caused
risk of developing testicular cancer (see by infection of a wound with spores of

testis, cancer of). If both testes are the bacterium CLOSTRIDIUM TETANI. The

undescended, infertility results. spores live mainly in soil and manure

A diagnosis is made during a physical but are also found elsewhere, including

examination after birth or later in infancy. in the human intestine. When the spores

Treatment is by orchidopexy, which usu- infect poorly oxygenated tissues they

ally reduces the risk of later infertility or multiply and produce a toxin that acts

testicular cancer (see testis, cancer of). A on the nerves controlling muscle acti-

poorly developed undescended testis vity. The most common symptom of this

may be removed if the other is normal. is trismus (commonly known as lockjaw).

test meal A procedure to measure the Other symptoms include stiffness of the

output of acid by the stomach. A naso- abdominal and back muscles, and con-

gastric tube is passed into the stomach traction of facial muscles, producing a

after an overnight fast, and a sample of fixed grimace. There may also be a fast

544

TETANY THALASSAEMIA

pulse, slight fever, and profuse sweating. coexisting anomalies: displacement of T
Painful muscle spasms then develop, and the aorta, narrowing of the pulmonary
may result in asphyxia if they affect the valve, a hole in the ventricular septum,
larynx or chest wall. The spasms usually and thickening of the right ventricle wall.
subside after 10 to 14 days. These cause poor oxygenation of the
blood pumped to the body, resulting in
About half a million cases of tetanus cyanosis and breathlessness. Tetralogy of
occur worldwide each year, but fewer Fallot occurs in about 1 in 1,000 infants.
than 20 occur in the UK. The diagnosis
is made from the symptoms and signs, Affected infants appear normal at birth.
and a course of tetanus antitoxin injec- Severely affected infants may become
tions is started. Most people recover cyanosed and breathless early in life.
completely if treated promptly. Other symptoms include failure to gain
weight and poor development.
Prevention of tetanus in the UK relies
on the DPT vaccination being given rou- An ECG, echocardiogram (see echo-
tinely during childhood; booster shots cardiography), and sometimes cardiac
are given every 10 years. catheterization are performed to confirm
tetany Spasms and twitching of the mus- the diagnosis and assess the severity of
cles, most commonly in the hands and the condition. The disorder is corrected
feet, although the muscles of the face, by open heart surgery.
larynx, or spine may also be affected. tetraplegia An alternative term for the
The spasms are caused by a biochemical condition quadriplegia.
disturbance and are painless at first; if thalamus One of 2 structures within the
the condition persists, the spasms tend brain consisting of a walnut-sized mass
to become increasingly painful. Muscle of nerve tissue. The thalami sit at the
damage may result if the underlying top of the brainstem and are connected
cause is not treated. The most common to all parts of the brain.
underlying cause is hypocalcaemia. Other
causes include hypokalaemia, hypervent- Each thalamus relays sensory infor-
ilation during a panic attack, or, more mation flowing into the brain. Some
rarely, hypoparathyroidism. basic sensations, such as pain, may
tetracosactide A drug used to test the reach consciousness within the thala-
functioning of the adrenal glands. Tetra- mus. Other types of sensory information
cosactide is a chemical analogue of the are processed and relayed to parts of
natural hormone corticotrophin (ACTH). the cerebral cortex (outer layer of the
ACTH stimulates the cortices of the brain), where sensations are perceived.
adrenal glands to secrete hormones such
as cortisol. To diagnose a disorder of the The thalamus seems to act as a filter
adrenal glands, a tetracosactide injection by selecting only information of particu-
is given and the blood cortisol level lar importance. Certain centres in the
measured. Failure of the level to rise thalamus may also play a part in long-
indicates an abnormality. term memory.
tetracycline drugs A group of antibiotic thalassaemia A group of inherited blood
drugs commonly used to treat bronchitis, disorders in which there is a fault in the
acne, syphilis, gonorrhoea, nongonococcal production of haemoglobin. Many of the
urethritis, and certain types of pneumonia. red blood cells become fragile and
If taken with milk, tetracyclines are not haemolyse (break up), leading to anaemia
absorbed effectively into the intestines. (see anaemia, haemolytic). Thalassaemia
Possible side effects include nausea, is prevalent in the Mediterranean, the
vomiting, diarrhoea, worsening of kidney Middle East, and Southeast Asia, and in
disorders, rash, and itching. Tetracyclines families originating from these areas.
may discolour developing teeth and are
therefore not usually prescribed for chil- Normal adult haemoglobin contains 2
dren under age 12 or pregnant women. pairs of globins (protein chains): alpha
tetralogy of Fallot A form of congenital and beta. In thalassaemia, a recessive de-
heart disease in which the heart has 4 fective gene results in reduced synthesis
of 1 of the chains. Usually beta-chain pro-
duction is disturbed (beta-thalassaemia).
Beta-thalassaemia minor (thalassaemia

545

THALIDOMIDE THERMOMETER

trait), which is never severe, is caused by therapeutic A term meaning related to

1 defective gene. The presence of 2 defec- treatment. The therapeutic dose of a

tive genes causes beta-thalassaemia drug is the amount required to have the

major (Cooley’s anaemia). The much greatest beneficial effect.

rarer disorder alpha-thalassaemia varies therapeutic community A method of

in severity; alpha-thalassaemia major treating drug dependence and alcohol

usually results in fetal death. dependence, and some personality dis-

Symptoms of beta-thalassaemia major orders, that entails patients living

appear 3–6 months after birth. If un- together as a group in a nonhospital

treated, bone marrow cavities expand, environment, usually under super-

leading to a characteristic enlargement vision. (See also social skills training.)

of the skull and facial bones. therapy The treatment of any disease or

Beta-thalassaemia major is diagnosed abnormal physical or mental condition.

from microscopic examination of the thermography A technique by which

blood, and from other blood tests. Treat- temperature patterns on the surface of

ment is with blood transfusions and, the skin are recorded in the form of an

sometimes, splenectomy. However, suc- image. Thermography provides clues to

cessive blood transfusions cause a the presence of diseases and abnormal-

buildup of iron in the body (see haemo- ities that alter the temperature of the

siderosis). Chelating agents are given by skin, such as problems of the circulation,

continuous infusion to help the body inflammation, and tumours. There are 2

excrete the excess iron. A bone marrow types of thermography. In one, a camera

transplant offers a cure for the disease. or scanner picks up infrared radiation

Genetic counselling is advised for par- naturally emitted from the skin. In the

ents or other close relatives of a child other, sheets of temperature-sensitive

with thalassaemia, and also for any per- liquid crystals are applied to the skin;

son with thalassaemia trait. they change colour in response to

thalidomide A drug that was withdrawn changes in temperature.

in the UK in 1961 after it was found to thermometer An instrument used to

cause limb deformities in many babies measure temperature. A traditional clin-

born to women given the drug during ical thermometer consists of a glass

pregnancy. Thalidomide is still used to capillary tube (a tube with a very fine

treat certain forms of Hansen’s disease bore) that is sealed at one end and has

(leprosy) and Behçet’s syndrome. a mercury-filled bulb at the other.

thallium A rare metallic element that is Modern versions of the clinical therm-

present as compounds in some zinc and ometer include an electronic probe

lead ores. Poisoning over a prolonged connected to a digital display, and an

period causes loss of hair, disorders of aural thermometer, which measures the

the nerves in the limbs, and disturbance THERMOMETER
of the stomach and intestines. Thallium-

T 201 (an artificial radioactive isotope) is Temperature
sometimes used in radionuclide scan- displayed
ning of the heart.

THC The abbreviation for tetrahydro-

cannabinol, the active ingredient in

marijuana.

theophylline A bronchodilator drug some-

times used to treat severe asthma and

heart failure in cases that have failed to

respond to other treatments. Theophyl-

line is usually given orally but can be

given intravenously as emergency treat-

ment. Possible adverse effects include

dizziness, nausea, vomiting, diarrhoea,

palpitations, and seizures. USING AN AURAL THERMOMETER

546

THIABENDAZOLE THOUGHT DISORDERS

temperature of the eardrum. Both ver- The condition is made worse by lifting T
sions give an almost instant reading. and carrying heavy loads or by increases
There are also disposable skin ther- in body weight.
mometers that employ heat-sensitive
chemicals, which change colour at Treatment of thoracic outlet syndrome
specific temperatures. These are not as usually consists of exercises to improve
reliable, however. Clinical thermom- posture, sometimes together with non-
eters may be calibrated in degrees steroidal anti-inflammatory drugs and
Celsius (centigrade), degrees Fahren- muscle-relaxant drugs. Severe cases
heit, or sometimes both. may be treated by surgical removal of
thiabendazole See tiabendazole. the 1st rib.
thiamine See vitamin B complex. thoracic surgery A surgical speciality
thiazides A type of diuretic drug. concerned with operations on organs
thiopental A barbiturate drug that is within the chest cavity. Sometimes, tho-
widely used as a general anaesthetic racic surgery is combined with heart
(see anaesthesia, general). Thiopental is surgery, in which case it is known as
given by intravenous injection. cardiothoracic surgery.
thioridazine An antipsychotic drug used thoracotomy An operation in which
to treat schizophrenia. It is now used only the chest is opened to provide access to
under specialist supervision because of organs in the chest cavity.
potentially serious side effects.
thirst The desire to drink. Thirst is one There are 2 types of thoracotomy:
means by which the amount of water in lateral and anterior. In a lateral thora-
the body is controlled (the other is the cotomy the chest is opened between 2
volume of urine excreted). ribs to provide access to the lungs,
major blood vessels, and the oeso-
Thirst is stimulated by an increased phagus. In an anterior thoracotomy, an
concentration of salt, sugar, or certain incision down the sternum (breast-
other substances in the blood. As the bone) provides access to the heart and
blood passes through the hypothalamus the coronary arteries.
in the brain, special nerve receptors are thorax The medical name for the chest.
stimulated, inducing the sensation of The thorax extends from the base of the
thirst. Thirst is also stimulated if blood neck to the diaphragm muscle.
volume decreases as a result of sweating, thought The mental activity that enables
vomiting, diarrhoea, severe bleeding, or humans to reason, form judgments, and
extensive burns. Thirst may also be solve problems. The essential features
caused by a dry mouth. of thought include the substitution of
thirst, excessive A strong and persis- symbols (in the form of words, numbers,
tent need to drink, most commonly due or images) for objects, the formation of
to dehydration. Other causes include symbols into ideas, and the arrangement
untreated diabetes mellitus and diabetes of ideas into a certain order in the mind.
insipidus, kidney failure, treatment with (See also thought disorders.)
phenothiazine drugs, and severe blood thought disorders Abnormalities in
loss. Abnormal thirst may also be due the structure or content of thought, as
to a psychological condition known as reflected in a person’s speech, writing,
psychogenic polydipsia. or behaviour. Schizophrenia causes sev-
thoracic outlet syndrome A condition eral thought disorders, including loss of
in which pressure on the brachial plexus logical connections between associa-
causes pain in the arms and shoulders, tions, the invention of new words (see
pins-and-needles sensation in the fin- neologisms), thought blocking (sudden
gers, and weakness of grip and other interruption in the train of thought), the
hand movements. Severe symptoms are feeling that thoughts are being inserted
usually caused by a cervical rib. Thoracic into or withdrawn from the mind, and
outlet syndrome may also be caused by auditory hallucinations.
drooping of the shoulders, an enlarged
scalenus muscle in the neck, or a tumour. Incoherent thoughts occur in all types
of confusion, including dementia and
delirium. Rapidly jumping from one idea

547