CME Complex Strabismus

CME

Complex
Strabismus

Dr. Subhash Dadeya
Dr. Savleen Kaur

DOS Office Bearers

Dr. Subhash C Dadeya Dr. Pawan Goyal Dr. Namrata Sharma Dr. Hardeep Singh
President Vice President Secretary Joint Secretary

Dr. Jatinder S Bhalla Dr. Vinod Kumar Dr. Manav Deep Singh
Treasurer Editor Library Officer

Executive Members

Dr. Dewang Angmo Dr. Jatinder Bali Dr. Shantanu Gupta Dr. C. P. Khandelwal

Dr. Rahul Mayor Dr. Vipul Nayar Dr. Rajendra Prasad Dr. Kirti Singh

DOS Representative to AIOS Ex-Officio Members

Dr. Jeewan S. Titiyal Dr. M. Vanathi Dr. Rakesh Mahajan Dr. Arun Baweja

CME

Complex
Strabismus

Dr. Subhash Dadeya
Dr. Savleen Kaur

Foreword

Respected Seniors and Dear Friends

“Strabismus” is one of the most challenging

subspecialty in ophthalmology. It’s not very

uncommon to encounter patients with strabismic

disorders in an ophthalmic outpatient department,

prevalence ranging from 0.5-5%. These disorders

besides causing cosmetic blemish, result in

disruption of normal binocular vision, altered

stereopsis and amblyopia. Early detection and Prof. (Dr.) Namrata Sharma
Hony. General Secretary
timely initiation of treatment therefore becomes

very important in order to prevent the occurrence of these sequelae. Ocular

examination should ideally begin in the newborn period and continue up to

all subsequent visits of the child. The understanding of various strabismic

pathologies has tremendously increased over the past two decades both in

terms of their etiopathogenesis as well as their management. There has been

an increased application of imaging modalities due to better understanding

of their role in detection and further classification of these strabismic

pathologies. No investigative modality can however replace or surpass a

good clinical examination. A comprehensive clinical examination is the key

for appropriately managing these disorders. This special issue on “Complex

Strabismus” focuses on complex strabismus syndromes and cases that pose

a management dilemma to strabismologists. The contributory chapters

are written by stalwarts in the field of strabismus from India and abroad.

The outline of all these complex situations provide a ready reckoner to a

strabismus surgeon.

We look forward for better understanding and learning of strabismic disorders
contributing to creation of good clinicians.

Prof. (Dr.) Namrata Sharma

Hony. General Secretary, DOS

ii CME on COMPLEX STRABISMUS

Contents

S.No. Title Page #
1. Etiology, Clinical Features and Management of 1
Lateral Rectus Palsy
22
2. Diagnosis and Management of Third Cranial
Nerve Palsy 42
54
3. Superior Oblique Palsy 77
99
4. Duane Retraction Syndrome 116

5. Dissociated Vertical Deviation 129
141
6. Monocular Elevation Deficit 154

7. Congenital Cranial Dysinnervation Disorders; 166
Expanding Horizons, Shrinking Borders 175
187
8. Strabismus in Craniosynostosis 211

9. Brown’s Syndrome

10. Lost Muscle in Strabismus Surgery­-
‘Useful Tips not to get Lost in Problems’

11. A Complex Strabismus Entity: Strabismus Fixus

12. Ocular Myasthenia Gravis

13. Treatment of Thyroid Related Strabismus

14. Post-traumatic Strabismus

CME on COMPLEX STRABISMUS iii

iv CME on COMPLEX STRABISMUS

01Etiology, Clinical Features and Management of Lateral Rectus Palsy

Etiology, Clinical Features
and Management of
Lateral Rectus Palsy

Dr. Jitendra Jethani, MD

Baroda Children Eyecare and Squint Clinic, Vadodara

The sixth nerve or the abducens nerve is responsible for the abduction
of the eye. The lateral rectus muscle receives its innervation from the
sixth nerve. The problem of the abducens nerve can occur at any point
starting from its origin at the pons in the brain to the lateral rectus
muscle in the orbit thereby resulting in sixth nerve or lateral rectus
palsy.

To understand the various causes of abducens nerve palsy, the anatomy
of the nerve should be understood which would help in locating the
lesion clinically. The abducens nerve start from the pons close to the
seventh cranial nerve nucleus and exits the brainstem. From here it
moves towards the subarachnoid space and then upwards along the
skull at the clivus. From here, the nerve course moves toward the base
of the skull at the petrous apex of the temporal bone. Hereon, it enters
the cavernous sinus. To understand the location of the nerve with
regards to other structures we must remember that trigeminal nerve
will be just lateral, and the internal carotid will be located medially.
Through the superior orbital fissure the nerve enters the orbit and ends
by innervating the lateral rectus muscle.1-3

Etiology

The occurrence and etiology of sixth nerve palsy or paresis is well
documented in several institution-based series.1–3 In a population-based
survey the various etiologies of sixth nerve palsy were documented.4
Microvascular etiology either hypertension or diabetes mellitus have
been commonly implicated in multiple studies.1, 4

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Etiology, Clinical Features and Management of Lateral Rectus Palsy

The most common associations in sixth nerve palsy, in a population-
based study, were found to be undetermined etiology, hypertension
alone, coexistent hypertension and diabetes, and trauma.4 They found
that 72% of patients in general population were of undetermined
etiology, traumatic, or vascular (hypertension or diabetes mellitus),
whereas only 4 % were associated with neoplasm. In our own work
in south Indian population5 microangiopathy was one of the most
common cause of lateral rectus paresis followed by undetermined
etiology amongst the non-traumatic neurologically isolated cases.
(Table 1)

Our study reemphasizes the view that a careful history and
neurologic examination will help distinguish those patients who
need extensive workup from those who can be observed. Holmes
et al6 predicted the risk factors for nonrecovery in traumatic palsy
as the time delay in recovery in cases of traumatic palsy, bilateral
palsy and female gender. We did not find a significant association of
female gender with the recovery of lateral rectus palsy; however, we
included lateral palsy with all the different etiologies. We also found
that the number of patients with unilateral lateral rectus palsy cases
recovered significantly, than the bilateral lateral rectus palsy even
when we included all the different etiologies. This was, however, not
true for the recurrences, which implies that the chances of recovery
may depend on unilateral/ bilateral palsy while the recurrence is
independent of unilateral or bilateral palsies. Our series has showed
11.9% of patients would show recurrence.

We found the incidence of sixth nerve palsy with a notably lower
incidence of neoplasm and higher incidence of diabetes and
hypertension than other studies in older adults. The younger adults
(20-40 years) are more likely to have some associated neurological
disorder as a cause for 6th nerve palsy than the relatively
benign microvascular disorder. The patients with nontraumatic
neurologically isolated sixth nerve palsy may undergo a focused
medical evaluation followed by close observation, whereas non–
neurologically isolated cases warrant a full neurological evaluation,
including prompt neuroimaging.

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Etiology, Clinical Features and Management of Lateral Rectus Palsy

Table 1. Various causes of non-traumatic neurologically isolated
lateral rectus palsy

Causes of non-traumatic neurologically isolated Percentage
lateral rectus palsy
Vascular etiology 51.2%
a. Hypertension + DM 11.2%
b. Only DM 27.2%
c. Only HT 12.8%
Undetermined 24.8%
Upper respiratory infection 16.8%
Congenital 2.4%
Multiple Sclerosis 1.6%
Myasthenia Gravis 0.8%
Pseudotumor cerebri 0.8%
Gradenigo syndrome 1.6%
Total 100%

Various causes have been enumerated in the table 2 regarding the non-
traumatic non neurologically isolated cases of lateral rectus palsy in
Indian population.

Table 2. Distribution of various causes of non-traumatic non
neurologically isolated lateral rectus palsy patients

Causes of non-neurologically isolated lateral Percentage
rectus palsy patients
Postsurgical neoplasm 6.3%
Aneurysm 6.3%
Cerebrovascular accident 6.3%
Intracranial neoplasm 12.5%
Meningitis 18.8%
Multiple sclerosis 25.0%
Sinus disease or mucocele 12.5%
Undetermined 12.5%
Total 100%

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Etiology, Clinical Features and Management of Lateral Rectus Palsy

Table 3. Cross tabulation of recovered and non-recovered patients
with cause of lateral rectus palsy

Cause Trauma Non-trau- Nontrau- Total
matic Neu- matic
rologically
non-neu-
isolated rologically

isolated

Recov- Recur- 0 11 (8.8%) 1 (6.3%) 12
ered rence

No re- 9 (60%) 73 (58.4%) 7 (43.7%) 89
currence

Total 9 (60%) 84 (67.2%) 8 (50.0%) 101

Non Surgery 5 12 (9.6%) 0 17
recov- done (33.3%) 29 (23.2%) 8 (50.0%) 38
ered
No sur- 1 (6.7%)
gery

Total 6 (40%) 41 (32.8%) 8 (50.0%) 55

Grand total 15 125 (100%) 16 (100%) 156
(100%)

Table 4. Distribution of recovered and non-recovered patients
with lateral rectus in different age groups (p=0.369)

Age group Recovered Not Recovered Total

<10 years 3 (42.9%) 4 (57.1%) 7

10 – 20 years 4 (50%) 4 (50%) 8

20 – 40 years 20 (60.7%) 13 (39.3%) 33

>=40 years 74 (68.5%) 34 (31.5%) 108

Total 101 55 156

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Etiology, Clinical Features and Management of Lateral Rectus Palsy

Table 5. Distribution of cause of lateral rectus palsy patients in
different age groups (p=0.000)

Trauma Nontraumatic Nontraumatic Total

neurologically non-

isolated neurologically

isolated

Under 10 3 (42.9%) 3 (42.9%) 1 (14.2%) 7
years

10- 20 years 2 (25%) 4 (50%) 2 (25%) 8

20- 40 years 6 (18.2%) 19 (57.6%) 8 (24.2%) 33

>= 40 years 4 (3.7%) 99 (91.7%) 5 (4.6%) 108

Grand total 15 125 16 156

Table 6. Cross tabulation of the patients who recovered with sex
distribution. P value is 0.930 which is not significant.

Recovered Total
Yes No

Male 54 (65.1%) 29 (34.9%) 83
Female 47 (64.4%) 26 (35.6%) 73
Total 101 (64.7%) 55 (35.3%) 156

Table 7(a). Shows the distribution of the recovered cases cross
tabulated with the unilateral and bilateral cases. P value is 0.023

Unilateral Bilateral Total

Recovered 99 2 101

Not recovered 49 6 55

Total 148 8 156

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Etiology, Clinical Features and Management of Lateral Rectus Palsy

Table 07 b. Shows the distribution of the recurrences in the
recovered cases cross tabulated with the unilateral and bilateral
cases. P value is 1.000

Recovered cases Unilateral Bilateral Total

Recurrence 12 0 12

No recurrence 87 2 89

Total 99 2 101

Pathogenesis

Only the ipsilateral lateral rectus that is solely innervated by the
involved peripheral sixth cranial nerve is affected; therefore, only
deviations in the horizontal plane are produced. In isolated cases of
peripheral nerve lesions, no vertical or torsional deviations are present. 
Depending upon the area at which the six nerve has been affected,
there could be co-existing problems in brain along with the lateral
rectus palsy.7 A simple way is to divide the pathway in five different
sections to know and find out clinically in determining the cause of
lateral rectus palsy.

A. The brainstem syndrome

A lesion in the posterior fossa may be compressive, ischemic,
inflammatory (most commonly multiple sclerosis in young adults)
or degenerative. It may involve the fifth, seventh and eighth cranial
nerves, as well as the pyramidal tract on the anterior aspect of the pons
and the cerebellum behind it.7-8 The various syndromes that may arise
due to a lesion in this region could be

1. Raymond’s syndrome:
a. Sixth nerve paresis
b. Contralateral hemiparesis (pyramidal tract)

2. Millard-Gubler syndrome:
a. Sixth nerve paresis
b. Ipsilateral seventh nerve paresis
c. Contralateral hemiparesis (pyramidal tract)

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Etiology, Clinical Features and Management of Lateral Rectus Palsy

3. Foville’s syndrome:
a. Sixth nerve paresis
b. Horizontal conjugate gaze palsy
c. Ipsilateral V, VII, VIII cranial nerve palsy
d. Ipsilateral Horner’s syndrome

B. The elevated intracranial pressure syndrome

Although it may be a false localising sign, the increased intracranial
pressure may secondarily affect the sixth nerve. The sixth nerve
ascends the clivus and turns 90 degrees anteriorly to enter Dorello’s
canal. Changes in intracranial pressure (ICP) either increased or
decreased may result in downward displacement of the brainstem
causing stretching of the sixth nerve which is tethered as it exits the
pons and inside Dorello’s canal. Approximately 30% of patients with
pseudotumor cerebri have sixth nerve paresis as the only neurologic
deficit,  in addition to papilledema and concomitant visual field
changes that result in blind spot enlargement. Other pathologies in the
subarachnoid space leading to sixth nerve palsy include hemorrhage,
meningeal or parameningeal infections (viral, bacterial, fungal),
inflammation (sarcoidosis) or infiltrations (lymphoma, leukemia,
carcinoma).

C. The petrous apex syndrome

The sixth nerve lies under the petroclinoid ligament. Contact with
the tip of the petrous pyramid makes the portion of the sixth nerve
within Dorello’s canal susceptible to pathologic processes. Gradenigo
described a syndrome of sixth nerve palsy associated with ipsilateral
decreased hearing (VIII nerve involvement), ipsilateral facial pain
in distribution of cranial nerve V and ipsilateral facial paralysis (VII
nerve involvement). This is especially important in cases secondary to
localized inflammations or extra-dural abscesses due to complicated
otitis media. Lesions of the cerebellopontine angle (especially acoustic
neuroma or meningioma) may involve the sixth and other contiguous
cranial nerves. It may be associated with decreased hearing, vestibular
symptoms and decrease corneal sensitivity that can imitate the petrous
apex syndrome.

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Etiology, Clinical Features and Management of Lateral Rectus Palsy

Pseudo-Gradenigo’s syndrome23
Hearing deficits in association with sixth nerve palsy and trigeminal
symptoms may be due to brain stem lesions, such as cerebello-pontine
angle tumor. Nasopharyngeal carcinoma may mimic Gradenigo’s
syndrome, since it can obstruct the Eustachian tube, resulting in serous
otitis media. Additionally, the carcinoma may subsequently invade the
cavernous sinus, causing sixth nerve paresis.

D. The cavernous sinus syndrome
The sixth nerve is close to 3rd, 4th and 5th (ophthalmic and maxillary
divisions) cranial nerves as well as the internal carotid artery and
the carotid sympathetic plexus. The cavernous sinus syndrome may
consist of deficits of two or more of these structures. The pituitary
gland, optic nerve, and chiasm may also become affected in this
syndrome. The sixth nerve may be involved in the cavernous sinus by
a variety of processes including the following.

Nasopharyngeal carcinoma. Nasopharyngeal carcinoma may present
with various symptoms including nasal obstruction, rhinorrhea,
epistaxis and serous otitis media secondary to obstruction of the
Eustachian tube.

Intracavernous internal carotid artery aneurysm: The prominent,
tortuous course of the internal carotid artery in the cavernous sinus
raises the suspicion of an aneurysm as a common etiology of the
cavernous sinus syndrome.

Carotid-cavernous fistula (CCF): A defect of the internal carotid artery
within the cavernous sinus will result in arterialization of the sinus,
and of the orbital and ocular veins which will result in the following
signs and symptoms: pain, proptosis, bruit, ocular pulsation, red eye,
chemosis and tearing, double vision and decreased vision.

Tolosa-Hunt syndrome: Tolosa-Hunt syndrome is an idiopathic, sterile
inflammation that primarily affects the anterior portion of the cavernous
sinus. Causes include trauma, syphilitic periostitis and neoplasms in
the region of the superior orbital fissure. These patients present with
orbital pain, ipsilateral involvement of the second through sixth cranial
nerves, as well as oculosympathetic palsy (Horner syndrome).

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Etiology, Clinical Features and Management of Lateral Rectus Palsy

Meningioma. Meningioma located along the medial aspect of the
sphenoid ridge, the anterior clinoid process, or the tuberculum sellae
may present with clinical features described for the cavernous sinus
syndrome of the sixth nerve. Exophthalmos and visual loss or visual
field defects such as bitemporal hemianopia, monocular blindness and
upper-temporal field defects in the other eye (junctional scotoma) may
occur.

Miscellaneous: A list of possible aetiologies of the cavernous sinus
syndrome of the sixth nerve is quite extensive and includes metastatic
lesions, neurofibroma, craniopharyngioma, multiple myeloma,
lymphoma, herpes zoster, temporal arteritis and syphilis.

E. The orbital syndrome
Proptosis is an early sign of the orbital syndrome and is frequently
accompanied by congestion of conjunctival vessels and conjunctival
chemosis. The optic nerve may be involved manifesting as optic
atrophy or papilledema. It is frequently difficult to distinguish between
cranial nerve (III, IV and VI) palsy and mechanical displacement of
the globe.Horner syndrome may be present, but the ptosis may not be
recognized because of proptosis.

F. Isolated Sixth nerve palsy syndrome

Ocular findings

The patient in an acquired lateral rectus palsy presents with symptoms
of double vision which increases on looking towards the affected eye.
This is associated with the inability to move the eye outward in the
affected eye. Some patients might complain of misalignment of eyes
and double vision in the primary position and may not appreciate
double vision in the extreme side gaze. This is mainly because the two
images are so far apart that the patient can ignore one of the images.
Some patients may present with face turn usually towards the side of
the affected eye. This is mainly to compensate for the double vision
in primary position. In early cases or paresis the double vision may
be mainly for distance and the movement restriction may be minimal.

The patient may present with other symptoms like blurring of vision

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Etiology, Clinical Features and Management of Lateral Rectus Palsy

or associated with neurological deficit depending on the cause of
lateral rectus palsy. In children with congenital lateral rectus palsy, it
is a diagnosis of exclusion as it is uncommon. The child would present
with esotropia, amblyopia and history of squint since birth. It should
always be differentiated from Duane’s retraction syndrome type I
which is more common.

Signs

The diagnosis is fairly easy and could be established with clinical
examination. Few important signs are

a. Incomitant Esotropia
The incomitance may be for near and distance. One the most

important features is that the angle of esotropia would increase
when measured on the affected side mainly because the affected
eye is unable to move whereas the contralateral yoke medial rectus
muscle receives more impulses.

Also primary deviation would be less than the secondary deviation
which is the amount of esotropia measured fixing unsound (here
Paretic) eye. This is due to the Hering’s law of equal in innervation.
When the sound eye is fixing, there is no increased innervation.
When the paretic eye (unsound eye) is fixing, the yoke muscle of
the sound eye receives more impulses and gets adducted more and
hence a greater angle.

b. Abduction restriction
Abduction restriction can be measured on a scale of 0 to -4 whereas

0 is normal limbus touching the outer canthus of the eye and -4
is no outward movement of the eye from primary position, An
ocular motility tester can also be used to grade the ocular motility.
It would be useful to know as this can measure the ocular motility
in millimeters.9

c. Past Pointing
If the patient is asked to point to an object in the field of action of

the paralyzed muscle while the sound eye is covered, his finger
will point beyond the object toward the field of action of the
paralyzed muscle. During this test, it is important that the patient

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Etiology, Clinical Features and Management of Lateral Rectus Palsy

points rapidly toward the object to avoid visual correction of the
error of localization while the hand is still moving toward the
object

d. Diplopia and Hess Charting
As the eye is moved inwards and there is an esotropia, there would

be an uncrossed diplopia mainly because the fovea is temporally
placed and the image is on the nasal retina which has a temporal
projection in the field. This would cause an uncrossed diplopia.
A small Hess chart would be seen in the affected eye. The outer
and the inner field would be closer to each other depending on the
acute or chronic lateral rectus paresis. (Figure 1)

Green glass in front of left eye Green glass in front of right eye

temp temp

O.S O.D

Figure 1: Both the eyes show small fields and overaction is seen on the nasal side.
The inner field is closer to the outer on so likely to be a recent onset palsy. The

midline has shifted nasally and so the eyes must also have shifted nasally and the im
‘to’ The midline has shifted nasally and so the eyes must have shifted nasally.

e. Forced Duction Test
After instilling the topical anesthetic drops, a forcep is used to

hold the eye at limbus. The eyeball is abducted to see if resistance
if felt. This helps in understanding and assessing the medial rectus
restriction.

f. Force Generation Test
Similarly as in Force duction test, this test is used to assess the

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Etiology, Clinical Features and Management of Lateral Rectus Palsy

power of the lateral rectus while the eye is held still. The patient is
asked to move the eyeball outward and the examiner tries to hold
the eyeball. A tug is felt as the force generated by the lateral rectus
muscle

g. Vertical Misalignment
Small vertical deviations in sixth nerve palsy are consistent with

normal hyperphorias that become manifest in the presence of
esotropia. Wong et al (2002) postulated that in peripheral sixth
nerve palsy, static head roll to either side induces hyperdeviation
in the eye on the side of the head tilt. Hyperdeviation of the same
eye induced by head tilt to either direction implicates a brainstem
lesion as the cause of paretic abduction. A vertical deviation > 5
PD indicates skew deviation or peripheral nerve palsy in addition
to abduction palsy.

h. Fundus Evaluation
It is important to evaluate the fundus to see the normal disc and

macula. Malignant hypertension or raised intracranial pressure
may show positive signs in fundus and help in doing the systemic
investigation.

Systemic Investigations

Once an isolated sixth nerve palsy has been established, patients can
be divided into two groups: The pediatric group and the adult group.
The workup for sixth cranial nerve palsy depends on what cause is
suspected.  An aggressive workup should be performed in children as
there is a significantly higher risk of neoplasm as a primary cause. In the
setting of abducens nerve palsy associated with trauma, neuroimaging
should be performed at the time of injury. If there is a concern of
elevated intracranial pressure as a cause, guarded lumbar puncture
should be performed. If the palsy is suspected due to an ischemic
cause, MRI is recommended as the preferred modality because of its
superior capability of imaging the posterior fossa.
1. Blood pressure measurement
2. Complete blood count (CBC)
3. Glucose tolerance test
4. Sedimentation rate

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Etiology, Clinical Features and Management of Lateral Rectus Palsy

5. Syphilis serology/VDRL
6. Thyroid function tests
7. Neuroimaging and radiological studies such as MRI with

enhancement
8. Skull series and stereoscopic submental- vertex basal views of the

skull (for nasopharyngeal carcinoma)
9. Chest radiography
10. Superior orbital fissure views
11. Otolaryngologic evaluation

Indications for imaging

1. Age less than 40 years
2. Non-Vascular Etiology
3. Multiple cranial nerve paresis
4. Neurologic Deficit
5. Recurrence
6. Non recovery
7. Presence of disc edema or pale disc

Differential Diagnosis (Table 08)

Neurologic Duane retraction Syndrome
Disorders Myasthenia Gravis
Restrictive Horizontal Gaze Palsy
Disorders
Dysthyroid Orbitopathy
Post-Surgical Medial Wall Orbital Fracture
Disorders
Lost Lateral Rectus
Miscellaneous Disinsertion of the Lateral Rectus
Excessive Lateral Rectus Recession
Medial Rectus Scarring and Contracture
Excessive Medial Rectus Resection

High Myopia with Inferior Lateral Rectus
Displacement
Inflammatory Orbital Disease
Spasm of Near Reflex

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Etiology, Clinical Features and Management of Lateral Rectus Palsy

Treatment

The course of a paralytic deviation starts with weakness of the lateral
rectus muscle with overaction of medial rectus of the same eye. The
maximum deviation is in the field of action of the paralyzed muscle
that is in a case of right eye lateral rectus paralysis it would be on the
right side of the patient. This stage is followed by overaction of the
antagonist of the paralyzed muscle. The esotropia would increase in
the primary position mainly because the right eye lateral rectus palsy
has cause overaction of the right eye medial rectus even in primary
position. This may lead to the contracture of the ipsilateral medial
rectus muscle. It is important to understand that this contracture may
prevent complete remission and may cause increased resistance to the
passive stretching of the lateral rectus.

This is followed by spread of comitance where in the deviation
becomes increasingly comitant. It may then no longer be possible to
detect a paretic component, and the angle of strabismus may be of the
same magnitude with either the paralyzed or sound eye fixating.

The treatment can be broadly divided into

1. None -- if mild with rapid recovery

2. Occlusion or blurring (with filter)
The reason for occlusion is twofold: One is to make the patient

free of irritating double vision. Any eye can be occluded to reduce
double vision. It is important to occlude or blur the unsound eye
when the patient is active. The sound eye may be occluded to
prevent contracture and impulses for the abduction should be sent
to the unsound eye. Some patients may find it difficult to occlude
the sound eye due to various reasons like past pointing etc.

3. Prism -- press-on or ground-in
Prisms (Fresnel) can be pressed on the glasses to alleviate diplopia.

Ground in prisms are possible only for angles less than 24 prism
diopters base out as it would make the glasses extremely thick and
bulky along with causing blurred vision.

4. Botulinum Toxin -- to medial rectus muscle of the affected eye

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Etiology, Clinical Features and Management of Lateral Rectus Palsy

Again, it serves two purposes one to reduce the double vision
and second to prevent contracture when given early in the course
of the disease. In the late period at the time of management
and an interesting approach is to inject it 2 weeks before
surgery. This helps in eliminating the need of doing a medial
rectus recession with the transposition procedure, even in the
presence of contracture, revealed by positive forced ductions.
Botulinum toxin can be injected in OPD or in Operation theatre.
Around 1.5 to 2.5 units of botulinum toxin in the muscle belly
either directly under visualization or under Electromyographic
(EMG) control.

5. Surgery
Almost 70% of patients of isolated 6th nerve palsy recover as per

our own study in Indian eyes depending upon the age, it is very
important to investigate and then observe for at least a period of
6 months. Even after 6 months, if there is still some recovery, we
should wait before embarking on any surgical decision.

Timing of Surgery

— 6 months

— 2 subsequent Hess charts showing no change

The decision of further management once it is established that the
patient would not recover is based on

A. Partial weakness (paresis)
B. Total weakness
C. Bilateral Sixth nerve palsy

A. Partial Weakeness or partial recovery

Regardless of the amount of deviation in the primary position the
partial recovery means that the abduction function has recovered at
least partially. The motility restriction should not be more than -2 for
getting good results postoperatively. On measuring with an ocular
motility tester, we believe the ocular motility in millimeter should be
at least 4.5 mm or more. (Figure 2)

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Etiology, Clinical Features and Management of Lateral Rectus Palsy

Figure 2: Shows right eye lateral rectus palsy with large esotropia in primary
position and only (-1) abduction restriction in right eye

• Recession of Medial Rectus
• Recession of Medial Rectus + resection of Lateral Rectus
The decision to do a single muscle or two muscle depends upon the
amount of deviation in the primary position with angle measured
fixing sound eye. An angle less than 18 prism base out can be easily
tackled with single muscle medial rectus recession.

If the amount of deviation is large, the patient would require a recess
resect procedure with the amount depending upon the amount of
deviation in the primary position. It would be preferable to use
adjustable sutures in adults and older children. Contralateral medial
rectus muscle Faden may sometimes help reducing incomitance.

C. Total weakness (palsy) (Figure 3 & 4)

The goal of surgical intervention in lateral rectus palsy is twofold:
improvement in primary position deviation and abduction
improvement. Transposition of vertical recti is a common procedure
for non-recovered lateral rectus palsy. Hummelsheim is credited
with describing the first rectus muscle transposition procedure
for treatment of paralytic strabismus in 1908.1  His procedure for
treating the esodeviation that results from sixth nerve palsy involved
splitting the vertical recti and reattaching the temporal halves of each
vertical rectus muscle adjacent to the insertion of the lateral rectus
muscle. Several modifications to this procedure have been described,
including those of O’Connor (1921), Berens and Girard (1950),
Wiener and Scheie (1952), Hildreth (1953), Costenbader (1958),
Schillinger (1959), Jensen (1964), Uribe (1968), and Knapp (1969).

16 CME on COMPLEX STRABISMUS

Etiology, Clinical Features and Management of Lateral Rectus Palsy

All extraocular muscle transpositions that involve the rectus muscles
shift forces of antagonist muscles to a rectus muscle that lies between
them and acts in the opposite plane.

Figure 3: Shows complete restriction of eye movement in abduction. The eye is
not able to reach the midline and shows large esotropia in primary position. Force

duction test is strongly positive (not shown in the image)

Figure 4: Complete right lateral rectus palsy with no abduction movement. The eye
is able to reach the midline though.

Full tendon transposition of vertical recti

The basic principle is to shift the superior rectus and inferior rectus
next to lateral rectus along the spiral of tillaux. The shifting of the
muscles would help improving the misalignment in primary position
and may help in improving the abduction movement. (Figure 5)
If done along with medial rectus recession, there is a risk of anterior
segment ischemia. A variation is to use botulinum injection in the
medial rectus as described above before the surgery and then do the
full tendon transposition

CME on COMPLEX STRABISMUS 17

Etiology, Clinical Features and Management of Lateral Rectus Palsy

Superior Rectus

LR

Inferior Rectus

Figure 5: Shows the vertical rectus transposed to lateral rectus muscle.
Full thickness transposition

Another variation is to do a split half vertical muscle transposition
(Hummelsheim procedure) along with medial rectus recession. Once
the vertical recti have been identified, engaged on a muscle hook,
and freed of surrounding attachments to intermuscular membrane
and anterior Tenon’s capsule, a small muscle hook is used to split
the muscle and tendon, beginning at the insertion, and extending
approximately 15 mm posteriorly sparing as much blood supply as
possible and then transposing this half toward the lateral rectus along
the line of spiral of tillaux.
The Jensen procedure is performed by splitting the palsied muscle and
joining the midportion of this muscle to the similarly split midportions
of the two adjacent rectus muscles. The dissection and splitting are
performed as described for the Hummelsheim procedure, but the
muscles are not disinserted. Instead, a 5-0 nonabsorbable fiber suture
is used to join the muscle bellies to affect a union of the two muscles
just anterior to the equator.

18 CME on COMPLEX STRABISMUS

Etiology, Clinical Features and Management of Lateral Rectus Palsy

In 1997, Foster described a modification of the traditional full-tendon
transfer which involves vertical muscle transposition augmented with
a lateral fixation suture. (Figure 6)

Superior Rectus

LR

Inferior Rectus

Figure 6: Shows foster augmentation suture between lateral rectus and superior
rectus on the superior border of lateral rectus and on the inferior border with inferior

rectus muscle after full thickness transposition

The goal of the Foster procedure is to close the gap between the
transposed rectus muscles and the nondisplaced paretic muscle, thereby
enhancing the desired force vectors of the transposed muscles. For a
lateral rectus palsy, a full-tendon transfer is performed as described
previously, with the addition of a 5-0 nonabsorbable, polyester
fiber suture placed through the sclera adjacent to the border of the
lateral rectus. This suture is placed 16 mm posterior to the limbus, or
approximately 8 mm posterior to the insertion of the lateral rectus,
and separate sutures are placed along the upper and lower borders of
the muscle. Once anchored in the sclera, the sutures are then passed
through the adjacent transposed vertical rectus, incorporating 25% of
its width. When the suture is pulled tight and tied, the gap between
the muscles is closed as the borders are drawn into approximation and
securely fixed at the equator.

CME on COMPLEX STRABISMUS 19

Etiology, Clinical Features and Management of Lateral Rectus Palsy

Nishida et al in 2003, described a muscle transposition procedure
in which the temporal halves of the vertical rectus muscle bellies
were sutured midway between the lateral rectus and vertical rectus
muscle onto the sclera. (Figure 7) Each vertical muscle belly was
longitudinally split from the centre of the muscle insertion for about
15 mm. They were also inserted at the sclera beside the superior or
inferior margin of the LR, 8 mm posterior to the LR insertion. Then
the lateral halves of the vertical rectus muscle bellies were transposed
to the scleral point beside the superior or inferior margin of the LR
and sutured onto the sclera so that the transposed muscle bellies could
be fixed.

Figure 7: Shows Nishida’s transposition of vertical rectus muscle towards lateral
rectus muscle

We compared Nishida’s procedure (NP) with partial VRT (with
medial rectus recession) and found that mean abduction preoperative
in NP group was 2.35 +/- 0.7 mm & VRT group was 2.6 +/- 0.8 mm.
The mean improvement in abduction was 2.4 +/- 0.6 mm & 3.55 +/-
0.4 mm in NT and VRT group. The improvement in primary position
angle was comparable in both groups. The partial VRT group showed
statistically significant improvement in abduction compared to NP.9

20 CME on COMPLEX STRABISMUS

Etiology, Clinical Features and Management of Lateral Rectus Palsy

Superior rectus Transposition

Mehendale et al in 2012 described single superior rectus muscle
transposition for Esotropia in Duane’s retraction syndrome and
lateral rectus palsy. Here medial rectus recession is done along
with transposition of temporal part of superior rectus adjacent to
the superior part of the lateral rectus muscle, and the nasal part was
reattached adjacent to the temporal part of the superior rectus muscle
insertion following the spiral of Tillaux. A double-armed 6-0 polyester
augmentation suture was placed by passing one needle through
the lateral one-quarter of the superior rectus muscle and the other
needle through the superior one-quarter of the lateral rectus muscle,
positioning this suture 8 to 12 mm posterior to the insertion of the 2
muscles.

References

1. Rush JA, Younge BR. Paralysis of cranial nerves III, IV, and VI. Cause and
prognosis in 1,000 cases. Arch Ophthalmol 1981; 99: 76–9

2. Richard BW, Jones FR Jr, Younge BR. Causes and prognosis in 4,278 cases
of paralysis of the oculomotor, trochlear and abducens cranial nerves. Am J
Ophthalmol 1992; 113: 489–96

3. Robertson DM, Hines JD, Rucker CW. Acquired sixth nerve paresis in children.
Arch Ophthalmol 1970; 83: 574–9

4. Patel SV, Mutyala S, Leske D, Hodge DO, Holmes J. Incidence, associations, and
evaluation of sixth nerve palsy using a population-based method. Ophthalmology
2004; 111:369–75

5. Jethani J, Pharande V, Mahalakshmi R, Maheshkumar S. Association of cause
and final outcome of sixth nerve palsy in south Indian population. Indian Journal
of Pediatirc Ophthalmology and Strabismus. 2012

6. Holmes JM, Beck RW, Kip KE, et al, Pediatric Eye Disease Investigator Group.
Predictors of nonrecovery in acute traumatic sixth nerve palsy and paresis.
Ophthalmology 2001; 108: 1457–60

7. Azarmina M, Azarmina H. The six syndromes of the sixth cranial nerve. J
Ophthalmic Vis Res. 2013;8(2):160-171.

8. Schmidt D. Classical brainstem syndrome. Definitions and history Ophthalmol-
oge. 2000;97:411–417

9. Jethani J. Abduction improvement in lateral rectus palsy post-surgery: Nishida’s
transposition versus Partial Vertical rectus transposition. Presented at AIOS 2019
Neuroophthalmology section.

CME on COMPLEX STRABISMUS 21

Diagnosis and Management of Third Cranial Nerve Palsy 02

Diagnosis and
Management of Third
Cranial Nerve Palsy

Dr. Birsen Gökyiğit, MD, Dr. Selcen Celik, MD

University of Health Sciences, Istanbul Beyoğlu Education and Research Eye Hospital,
Istanbul, Turkey

The third cranial nerve (Oculomotor nerve) is thoroughly complex
in nature because it innervates four of the six extraocular muscles
including superior rectus, inferior rectus, medial rectus and inferior
oblique. Additionally, besides innervating superior levator palpebrae
muscle, it also provides parasympathetic innervation to the pupillary
sphincter and ciliary body. To understand the partial or complete
paralysis of the oculomotor nerve and their management, we need to
start with the anatomy of the oculomotor nerve.

Anatomy of the Oculomotor Nerve

Oculomotor nerve can be analyzed in five segments including nucleus
and fasciculus which are located in midbrain, subarachnoid space,
cavernous sinus and the orbit.

Nucleus: Oculomotor nuclear complex involves individual subnuclei
which are responsible for the actions of each muscle innervated by
the oculomotor nerve. The central caudal nucleus is located midline
and innervates both right and left superior levator palpebrae muscles.
Therefore, lesion affecting the third nerve nucleus results in bilateral
ptosis. All the other subnuclei (inferior rectus subnuclei, superior
rectus subnuclei, inferior oblique subnuclei, medial rectus subnuclei
and Edinger- Westphal subnuclei) in the oculomotor nuclear complex
are paired and except for superior rectus subnuclei innervate the
ipsilateral eye. Because superior rectus fascicles decussate in
the nuclear complex, superior rectus subnucleus innervates the
contralateral eye. Edingher Westphal subnuclei send parasympathetic

22 CME on COMPLEX STRABISMUS

Diagnosis and Management of Third Cranial Nerve Palsy

signals to the pupillary constrictors and the muscles of accommodation
in the ciliary body. Lesions affecting the third nerve nucleus result
in bilateral ptosis, contralateral superior rectus palsy and ipsilateral
palsies of inferior rectus, medial rectus, inferior oblique and ipsilateral
parasympathetic involvement of pupillary constrictor muscles and the
muscles of accommodations in the ciliary body.

Fascicles: The fascicles of third cranial nerve traverse the midbrain
ventrally and pass thorough the red nucleus and the cerebral peduncle.
Although the lesions involving fascicles in the midbrain may
occasionally represent like isolated third nerve palsy, the involvement
of red nucleus and the cerebral peduncle usually accompanies.

Subarachnoid space: The fibers of oculomotor nerve unite in the
subarachnoid space and travel to cavernous sinus. The nerve has an
important relationship with the Willis Polygon. It courses between
the superior cerebellar and posterior cerebral arteries and then travels
inferior and lateral to posterior communicating artery before entering
the cavernous sinus. Since the pupillomotor fibers travel at the outer
surface of the nerve superficially, the mass lesions in this region
including aneurysms lead to compression of the third cranial nerve.
Ischemic pathologies instead affect the central portion of the nerve
and usually are not associated with pupillary involvement unlike
aneurysms.

Cavernous sinus: The oculomotor nerve lies superolateral in the
cavernous sinus. It is divided into superior and inferior divisions at the
superior orbital fissure however this type of division may be seen in
the lesions anywhere from the brainstem to the orbit. Since the fourth
and sixth cranial nerve and the ophthalmic division of fifth cranial
nerve also travel in the cavernous sinus, multiple cranial neuropathies
may be observed in the lesions of cavernous sinus.

Orbit: Superior division of the oculomotor nerve innervates the
superior rectus and levator palpebrae muscles. Therefore, the lesions
of this division lead to ptosis and elevation deficiency. Inferior
division innervates the inferior and medial rectus muscles, inferior
oblique muscle and also gives parasympathetic signals to pupillary

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Diagnosis and Management of Third Cranial Nerve Palsy

sphincter muscle and the ciliary body. Lesions arising from the inferior
division cause decreased depression and adduction with involvement
of pupillary dilatation.

Etiology of Third Cranial Nerve Palsy

The reasons of oculomotor paralysis can be evaluated under several
headings as

1. Idiopathic (in about 25% of cases the reason of palsy is not found)
2. Nerve compression (aneurysm, brain tumor, hydrocephaly etc.)
3. Ischemia (Diabetes Mellitus, atherosclerosis, hypertension and

giant cell arteritis)
4. Trauma (open/closed head traumas)
5. Inflammation (Viral, post-viral, bacterial, Multiple Sclerosis)
6. Miscellaneous (post several minor surgical injections, radiation,

Myasthenia Gravis, etc.)
Third nerve palsy may be congenital or acquired in the pediatric
age group. While 40-50% of the cases were congenital, the most
common causes of acquired palsies in children include trauma (20%),
neoplasms of the brainstem and posterior fossa (17%), inflammatory
conditions and migraine. Aberrant regeneration was seen in 45% of
this group. Additionally, the congenital absence of cranial nerve and
muscle should be encountered in children. All acquired third-nerve
palsy cases should be investigated thoroughly to exclude any space-
occupying lesion in children.

Ischemia (20%) builds up the most common cause of third cranial
nerve palsy in adults, especially patients older than 45 years with
diabetes, 60% are affected by micro vasculopathy. Ischemia followed
by trauma (15%), aneurysm, neoplasms, demyelization and viral or
bacterial infection. In cases with pupillary involvement, the cause
of paralysis may be a life-threatening disease. Following paralysis
aberrant regeneration also seen in adult patients and should alert the
physician to a life-threatening condition.

24 CME on COMPLEX STRABISMUS

Diagnosis and Management of Third Cranial Nerve Palsy

Clinical features in Complete Oculomotor Palsy

While general features of cases in complete palsy are similar,
oculomotor palsy clinics are changed according to cases being
congenital or acquired, or if have aberrant regeneration or periodic
appearance.

General features in affected eye in complete cranial third nerve palsy
are ptosis (due to paralysis of levator palpebra superioris) and ocular
deviation as eyeball is turned out and slightly down with intorsion.
(Figure 1) This occurs from healthy lateral rectus and superior oblique
activity. Ocular movement is restricted in adduction, elevation and
depression because of medial rectus, superior rectus and inferior
rectus paralysis. Extorsion is enabled due to both inferior oblique and

Figure 1: Acquired left cranial nerve third palsy in adult.

Figure 2: Congenital cranial nerve third palsy in left eye

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Diagnosis and Management of Third Cranial Nerve Palsy

inferior rectus paralysis. General relaxation of tonus four of the six
extraocular muscles may produce a small degree proptosis. Pupil
is fixed and dilated and accommodation is completely lost due to
paralysis of sphincter pupillae and ciliary muscles. However, vascular
causes such as diabetes and hypertension often cause pupil sparing
palsy. Accommodation and pupillae size are normal in these cases.
Patients complain for diplopia and have abnormal head posture. Their
face is turned on the opposite side, head tilted towards the effected
side and chin is slightly elevated. The cases who have severe ptosis
has not diplopia and head posture.
In congenital third nerve palsy, intraocular muscles are usually not
involved and ptosis is not severe as acquired cases. (Figure 2) But
suppression and amblyopia is more common in congenital cases.
Aberrant regeneration can occur both in congenital cases and following
acquired third nerve palsy (Figure 3) It may be miswiring of axons
proximal portion of affected nerve. But also, it might be a sign of
slowly growing intracavernous meningioma or carotid aneurism in
acquired cases, both of which are life threatening factors. Aberrant
regeneration can be seen as several types. Pseudo -Greafe’s sign is
more visible, while patient attempts to down gaze upper lid makes
elevation. Also, palpebral fissure widening or narrowing, or globe
retraction during the eye movement and pupillae strange reactions are
seen in aberrant regeneration.

Figure 3: Aberrant regeneration late stage following recess resect procedure.

26 CME on COMPLEX STRABISMUS

Diagnosis and Management of Third Cranial Nerve Palsy

Cyclic oculomotor paralysis is very rare. While the cases are normal
in spastic phase almost complete paralysis noted in paretic phase. But
in time paretic phase takes more times in cycles.

All above information are about complete cranial nerve palsy. But
in management of these cases, it is important to distinguish if the
palsy is complete or incomplete. Incomplete palsies can present as
isolated or multiple muscle palsy. Management and expectations from
the treatment varies in the setting of complete or incomplete palsy.
The treatment option is selected according to the extent of palsy and
recovery in each individual patient.

Management of Complete Third Cranial Nerve
Palsy

In complete third nerve palsy, because the medial rectus, inferior
rectus, superior rectus and inferior oblique complete paralysis were
present, the management is most difficult, and the results are most
unpredictable in strabismus.

Management began with exploration of reason(s) and meticulous
examination. Because basically the treatment of nerve palsies is
needed to solve the basic problems. Then, conservative treatment
might be performed. After 6-12 months onset of strabismus surgical
treatment is needed.

In onset of strabismus in investigation stage, neurology, rheumatology,
pediatric and internal medicine consultation is required. Radiological
and other tests may show the reason of the paralysis. If the reason
is definitely found, patient should be referred to related clinic for
treatment. If there is no surgical cause found, patient followed with
conservative treatment.

It is essential to initially make the first six months of observation as
a conservative treatment. This period can be extended to one year in
patients who show positive development during the waiting period.
Paralysis that develop due to microangiopathy show spontaneous
improvement over time. Spontaneous recovery in post-traumatic
paralysis is around 30%. However, waiting longer in patients with
no positive course in six months affects the outcome of treatment

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Diagnosis and Management of Third Cranial Nerve Palsy

negatively. Amblyopia occurs both due to deviation and most
importantly with severe ptosis, and treatment is very important for the
children. The treatment must be vigorous and the control examination
should not be neglected. Also, surgical treatment should not be delayed
too long in childhood.
Alternate or affected eye patching, or use prismatic glasses for
preventing diplopia is another type of conservative treatment. Either
Fresnel prism or prismatic glasses also very helpful after surgical
treatment for enhance the diplopia free area.
The injection of botulinum toxin A (btx) to the unaffected muscle for
preventing the healthy muscle(s) contraction and fibrosis is one of
the very important conservative treatment choices which sometimes
is enough for the complete treatment of paralysis (Figure 4). Also,
giving vitamin B-complex for neurogenic support and systemic steroid
if needed are the other nonsurgical ways of the treatment. During the
observation, measurement of deviation and documentation of diplopia
and gaze restriction is important for following the course of paralysis.

Figure 4. Complete CN 3rd. palsy at left eye (above), 3 months later left lateral
rectus Btx. Injection (belove)

28 CME on COMPLEX STRABISMUS

Diagnosis and Management of Third Cranial Nerve Palsy

Surgical Treatment of Complete Third Cranial
Nerve Paralysis

Surgical treatment must be planned for at least 6-8 months after the
paralysis and this period may be extended up to one year. Because,
after the operation, the patient could not achieve a good binocular
vision area, the results should be shared with the patient and ptosis
surgery may be delayed in some to prevent incapacitating diplopia. In
surgical treatment, associated factors such as pupillary involvement,
aberrant regeneration, lateral rectus contracture (in old cases), poor
Bell phenomenon, presence serious ptosis and amblyopia might be
taken into account and the situation with probable complication(s)
must be discussed with the patient or family. In addition, multiple
operation probability and almost fixate (un mobile) eye in primary
position target, also must be shared with the related persons. Another
very important point which need to be shared with the patients is the
goal of the surgical treatment is the almost orthophoria in primary
position with the good cosmetics and obtain as large as possible
binocular vision area at the end of the surgery(s).

Surgery for complete third nerve palsy is challenging and includes
several methods such as:

Conventional supramaximal recession-resection procedure of
horizontal rectus muscles. Paretic medial rectus is resected up to
10 mm and lateral rectus muscle is recessed up to 12 mm with this
technique. However, if the function of MR is severely affected this
procedure does not result in satisfactory outcomes. Additionally, lateral
rectus muscle contracture may be present as a result of long-standing
palsy and therefore even after a successful surgery, shortening of LR
as well as lengthening of paralyzed MR muscle may occur in time.
These factors may lead to return to preoperative exotropia drift. And
as a result, this operation is not effective in these cases.

Lateral Rectus disinsertion procedures: Since there is an unopposed
action of lateral rectus muscle in 3rd nerve palsy, this unopposed force
should be balanced in order to achieve primary position alignment.
In addition, various levels of contracture of the lateral rectus muscle
may be present in the setting of a long-standing large angle exotropia.

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Diagnosis and Management of Third Cranial Nerve Palsy

Methods of profound weakening of the lateral rectus muscle include
supramaximal recession, disinsertion of the lateral rectus muscle
from the globe (free tenotomy), disinsertion of the muscle from the
globe and reattachment of it to the lateral orbital periosteum using
nonabsorbable sutures.

Globe anchoring procedures: The globe can be anchored to the
periosteum of the anterior lacrimal crest or medial orbital wall by
using periosteal flaps, fascia lata, 5-0 polyester sutures, silicone band
and superior oblique tendon. In complete third nerve palsy, because
the medial rectus, inferior rectus, superior rectus and inferior oblique
complete paralysis were present; operation methods such as recession-
resection and muscle transposition are not effective in these cases.

Traction sutures: Since in a complete third nerve palsy there is only
an unopposed action of lateral rectus muscle and the superior oblique
muscle, the eye is fixed in a divergent position against the orbital static
forces which try to pull the eye back to the center. In time, the eye
adopts this position and the static forces stop trying to remove the eye
position to the center against the unopposed action of the lateral rectus
muscle. This is the reason of unsatisfactory results after supramaximal
horizontal rectus muscle surgery. In this case unopposed action of the
lateral rectus muscle should be weakened profoundly in combination
with supramaximal resection of the medial rectus muscle and the
traction sutures which keep the eye in adducted position can be
inserted and left in situ for weeks to prevent the eye moving back to
the preoperative position after surgery.

Two Ethibond sutures are passed through the insertion of the superior
and inferior rectus muscles right next to the sclera and taken to the
medial canthus, then they are brought to the surface through the lid
skin and pulled up to move the eye into adduction and are then tied.
The authors said that, nasal traction suture have satisfactory results in
long term.

Superior oblique tendon transposition: In cases where the SO muscle
is intact, the transposition of this muscle by shortening to the nasal
medial rectus area, provides a partial treatment. It seems only a
slight reduction in the deviation. If the medial rectus muscle lacks

30 CME on COMPLEX STRABISMUS

Diagnosis and Management of Third Cranial Nerve Palsy

any function, transposition of the superior oblique muscle is usually
necessary in order to imply an adducting force to the globe.

Peter and Jackson described a technique involving fracturing of the
trochlea and attachment of the shortened superior oblique tendon
to the medial rectus muscle insertion. However, this procedure has
technical difficulties and may result in the superior oblique tendon
being severed inadvertently at the trochlea, especially in an adult
patient with a calcified trochlea. To avoid these difficulties, Scott
described an alternative technique of transposition of the superior
oblique tendon without trochleotomy. In Scott’s technique, the superior
oblique tenotomy is performed at the medial border of the superior
rectus muscle and then the tendon is sutured to the sclera 2.0 to 3.0
mm anterior to the medial side of the superior rectus muscle insertion.
This procedure is often performed in combination with supramaximal
recession-resection of horizontal rectus muscles.

Unfortunately, in many cases the 3rd and 4th nerves are affected
together and the eye is in extreme exotropia with under effects of only
one healthy extraocular muscle is lateral rectus.

Therefore, in complete third nerve palsies, the method to be selected
in the cases is; either completely eliminating the effect of the lateral
rectus and mechanically pulling the globe medially or transposing the
strength of the lateral muscle, the only muscle remaining intact, into
medial rectus area.

Nasal transposition of lateral rectus: Nasal transposition of the LR,
either whole muscle in superior or inferior of medial rectus are used in
several cases with partial success. Also split lateral rectus transposition
to the globe medial area near vortex vein are used years ago but the
results were disappointing in two cases.

Split lateral rectus nasal transposition operation while using splitting
and reattaching the arms superior and inferior to the insertion of
the medial rectus for treating strabismus for complete CN 3rdpalsy
seems to be the most effective procedure. Gokyigit’s method and its
modifications published with very successful results and with non-
serious mild and transient complications. During the split lateral

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Diagnosis and Management of Third Cranial Nerve Palsy

rectus transposition of medial rectus insertion, originally superior

and inferior parts of lateral rectus pass through under both rectus and

oblique muscle complexes in both the inferior and superior area. But

successful results are obtained while lateral rectus parts were passed

under only rectus muscles. (Figure 5.)

A3 B8 Figure 5: Superior aspects of split

4 2 lateral rectus operation in A, and

5 15 inferior aspects of operation in B.

7 1. Lateral rectus,

6 2. Superior rectus,
3. Superior parts of lateral rectus,

4. Superior oblique muscle,

5. Medial Rectus,

1 6. İnferior oblique muscle,

7. Inferior rectus muscle.

8. Inferior part of Lateral rectus

muscle

Some simplified modifications of this operation, inferior and superior
oblique muscles dis-insertion, were performed. We noted some
advantages and disadvantages in two techniques. While original
application is difficult to perform but allows safe superior or inferior
rectus recession when needed. On the other side, simplified technique
is quite easy to perform compared to original technique, but the
recession or other application performance are not safe enough if
needed later.

If there is still deviation, it can be treated via either in same eye
additional operation or fellow eye interventions. Vertical recti posterior
fixation sutures and lateral rectus recession operations are the most
common performed fellow eye operations for residual deviations.

Isolated Superior Rectus Muscle Paralysis

Superior rectus palsy can be seen mostly congenital or secondary in
trauma. While defective elevation in abduction and normal elevation
in adduction are noted in recent onset cases, the findings are changed
as elevation deficit is observed in abduction, adduction and primary
position in older cases. Ipsilateral inferior rectus and contralateral
inferior oblique muscles overaction with mild excyclotropia are also
found. (Figure 6)

32 CME on COMPLEX STRABISMUS

Diagnosis and Management of Third Cranial Nerve Palsy

Figure 6: Isolated superior rectus paralysis at the right eye

Effected eye is seen hypotropic in primary position with absence of
Bell phenomenon, as face is turned upward, the chin is elevated, the
head is inclined toward the healthy eye. Previously explained ocular
torticollis and pseudo ptosis are the other characteristics for superior
rectus paralysis. Pseudo ptosis and true ptosis must be discriminative
for treatment plan. For this reason, patient try to fixate with the effected
eye. In pseudo ptosis, upper lid is found to be in normal anatomic
position.

Monocular elevation deficiency, structural pathology and mechanical
causes that restrict the elevation are in differential diagnosis. Most
well-known restrictive reasons are fibrosis, heavy eye due to high
myopia, endocrine orbitopathy, orbital floor blow out fracture or
myositis. While force duction test is positive in all above diagnosis
and in some anatomical pathologies, test is negative in paralysis.
Rarely, in very long duration palsies, force duction test may be found
as positive for resulting secondary ipsilateral inferior rectus fibrosis.

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Diagnosis and Management of Third Cranial Nerve Palsy

In early cases, botulinum toxin injection of ipsilateral inferior rectus
can be obtained good results. Conservative treatment is as similar
with the complete palsy. After 6-12 months follow up there are
several choices for surgical treatment depending on condition of
the case. These are, Ipsilateral inferior rectus recession, Ipsilateral
superior rectus resection, Vertical transposition of horizontal recti to
the superior rectus area, Ipsilateral inferior rectus faden-operation,
Contralateral superior rectus faden-operation, Nasal transposition of
superior oblique muscle.
In above list, inferior rectus recession needs to have a specific attention
for preventing lower lid retraction. If operation plan includes more
than 4mm recession, novel inferior rectus recession, which doesn’t
cause lover lid retraction, may be taking into account. In the mild
form of superior rectus palsy, resection of superior rectus or recession
of the yoke inferior oblique may be performed. As treatment choice
for isolated superior rectus palsy, In the moderate form, recession
of inferior rectus muscle is added to the resection of superior rectus
muscle. In the severe form, transposition of vertical recti either tendon
or partial or whole muscle is performed (Figure 7). Previous operation
may be combined with recession of the superior rectus of the fellow
eye if needed.

Figure 7: Left isolated superior rectus palsy at left, following transposition operation
at right.

Isolated Medial Rectus Muscle Paralysis

Isolated medial rectus paralysis without other inferior division of CN
3rd muscles involvement is very rare in clinical observation. There is

34 CME on COMPLEX STRABISMUS

Diagnosis and Management of Third Cranial Nerve Palsy

exotropia with adduction deficit. Patients’face turns toward the healthy
eye (Figure 8). Differential diagnosis of internuclear ophthalmoplegia,
synergistic divergence, Duane’s retraction syndrome Type II, and
supranuclear disorders might be investigated.

Figure 8: Isolated medial rectus paralysis at the right eye

Recent cases can be managed with ipsilateral lateral rectus Btx
injection. After 6-12 months onset of diagnoses, according to severity
of paralysis lateral rectus weakening procedure for fellow eye,
ipsilateral lateral rectus recession and/or vertical recti transposition or
recess-resect procedure can be performed.

For example, in the mild form of isolated medial rectus palsy,
recession of the yoke lateral rectus muscle may be beneficial or may be
combined with medial rectus resection. In the moderate form, medial
rectus resection is combined with lateral rectus recession. However,
in the severe form, transposition of inferior rectus and superior rectus
should be performed in combination with medial rectus resection and
yoke lateral rectus muscle recession.

Total tenotomy of the lateral rectus muscle, resection of the medial
rectus muscle and tenotomy of the superior oblique and myectomy
of the inferior oblique muscles perform for aberrant innervation
treatment. Split lateral rectus medial transposition can also be used for
aberrant innervation or mis-innervation treatment.

CME on COMPLEX STRABISMUS 35

Diagnosis and Management of Third Cranial Nerve Palsy

Isolated Inferior Rectus Muscle Paralysis

There is down gaze limitation in inferior rectus palsy especially in
abduction, incyclotorsion and hypertropia. (Figure 9) Patients have
chin down head position. Isolated inferior rectus palsy is also rare,
it is generally congenital but also it can be seen following orbital
floor fracture. Complication of vascular disease is also the cause of
acquired palsy. In early stage, we cannot use any protective procedure
similar as to the other palsies. Because severe ptosis complication
superior rectus Botulinum toxin injection is not advised. After waiting
at least 6 months from onset, one of the following surgical procedures
may be performed. In surgical treatment, inferior muscle resection
alone, inferior rectus plication, superior rectus recession, reverse
Knapp procedure and inferior oblique muscle anterior transposition
techniques are eligible for affected eye. Inferior rectus posterior
fixation suture operation for fellow eye is also beneficial.

Figure 9: Isolated inferior rectus paralysis at the right eye

For example, in the mild form of inferior rectus palsy, resection or
plication of inferior rectus or recession of yoke superior oblique
may be effective. In the moderate form, inferior rectus resection is

36 CME on COMPLEX STRABISMUS

Diagnosis and Management of Third Cranial Nerve Palsy

performed in combination with superior rectus recession. In the severe
form, transposition of medial rectus and lateral rectus (reverse Knapp
procedure) and recession or faden-operation of the inferior rectus of
the fellow eye can be performed.

Isolated Inferior Oblique Muscle Paralysis

Inferior oblique muscle paralysis also is very rare, there is a
noticeable lack in elevation in adduction. (Figure 10) It needs to be
differentiated from Brown syndrome and severe ipsilateral superior
oblique hyperfunction. In palsy, there is a negative force duction with
A pattern strabismus. Surgical plan is created according to amount of
hypertropia. In the mild form, recession of the yoke superior rectus
may be enough. If hypertropia is less than 10PD in primary position,
ipsilateral superior oblique tendon expander or superior oblique split
tendon elongation is performed. If hypertropia is over 10PD in primary
position contralateral superior rectus recession might be added to
previous operation choice.

Figure 10: Left inferior oblique isolated palsy. Diagnosis was verified with forced
duction test.

Conclusion

Because the oculomotor nerve innervates four of the six extraocular
muscles as well as the superior levator palpebrae, the pupillary
constrictor and the ciliary body, complete palsy of the third cranial nerve
presents with marked limitation in elevation, depression and adduction
in association with ptosis, mydriasis and loss of accommodation. The
affected eye is aligned in an abducted position usually with a slight
depression and intorsion due to unopposed action of lateral rectus and
superior oblique muscles. Correction of strabismus due to complete
oculomotor nerve palsy is one of the most challenging issues in the

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Diagnosis and Management of Third Cranial Nerve Palsy

strabismus field. In complete palsies, it is not usually possible to
restore binocular single vision and achieve satisfactory functional
outcome because of the extent of the muscles involved. Actually,
complete oculomotor paralysis can be surgically corrected. However,
the excellent result is that the eyes are in the primary position, with
the widest possible binocular visual field, and a acceptable cosmetic
appearance. However, in the setting of incomplete palsies, the goal of
the surgery can be broadened to improve ocular motility and center
and enlarge single binocular vision area.

Following the diagnosis of oculomotor palsy, several consultations and
lab investigations are required. Sometimes cranial third palsy is only
symptom for the life threating disease. During the consultations, for
preventing the healthy muscle(s) contraction and fibrosis, botulinum
toxin A (btx) injection of the unaffected muscle maybe helpful.

On the other hand, when planning the operation of any of the partial
cranial nerve third palsy, weakening of the strong muscle, strengthening
of the weak muscle and if there are ineffective muscles, applying the
transposition procedures are the basic rules. Another important point
is that if there is ptosis, ptosis operation should take into account that
those patients do not have Bell phenomenon. Following both operation
of complete paralysis and partial palsies, complications should always
be expected and followed.

It should always be kept in mind that oculomotor partial paralysis
can mimic many types of strabismus, care should be taken in the
differential diagnosis.

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CME on COMPLEX STRABISMUS 41

Superior Oblique Palsy 03

Superior Oblique Palsy

Dr. Miho Sato, MD, Ph.D.

Hamamatsu University School of Medicine

Introduction

Superior oblique palsy (SOP) is one of the most common causes of
vertical deviation in children and adults. There are two major origins
of SOP: one is congenital, and the other is acquired, and they have
different characteristics. The trochlear nerve is the smallest and longest
of the ocular motor nerves; therefore, it is vulnerable to trauma and is
easily affected bilaterally. It is the only cranial nerve to emerge on the
dorsal surface of the brainstem and is the only nerve to cross entirely.

Occasionally, patients with congenital SOP visit ophthalmology
clinics in adult age. Because they compensate their eye position with
the abnormal head posture, they do not notice strabismus until they
become unable to compensate for their abnormal eye positions and
start noticing diplopia or having difficulty in fusing. In such cases, we
need to differentiate congenital SOP from acquired SOP. Congenital
SOP patients often have large fusional amplitudes, large vertical
deviations, and little or no torsional diplopia. Conversely, acquired
SOP patients have small fusional amplitude, relatively small vertical
deviation, and severe torsional diplopia. The anatomical characteristics
of the trochlear nerve,1 superior oblique (SO) tendon,2 SO muscle,3
and muscle-tendon relationship4 in congenital SOP were identified by
MRI and intraoperative findings. The acquired SOP patients did not
exhibit tendon anomalies or the absence of the trochlear nerve in the
brain.

There are clinical techniques for diagnosing SOP, but clinical findings
may not always reflect true SOP and we need to recognize their various
clinical findings.

42 CME on COMPLEX STRABISMUS

Superior Oblique Palsy

Incidence

The incidence of SOP in the general population remains unclear. von
Noorden reported that in their experience of treatment of SOP in 10
years, 39.5% had a congenital origin, followed by traumatic (34%),
idiopathic (23.2%), and neurologic (2.9%) paralysis.5 However, if
the incidence is estimated in neuro-ophthalmology clinics, traumatic
cases may be observed more frequently.

Clinical features

The SO muscle depresses, intorts, and abducts the eye. Therefore,
paresis of this muscle will cause the involved eye to have some
combination of hypertropia, excyclotropia and esotropia. Patients may
complain of diplopia, which can be vertical, diagonal, or torsional.

Compensatory head posture is the most common sign of SOP. This
condition is called torticollis with the head tilted away from the
affected side, the face turns away from the affected side, and the
chin down. This compensatory head posture helps patients maintain
fusion in the least abnormal eye position. Patients with bilateral SOP
exhibit a chin-down position to adapt to fusion with the least torsional
deviation.

• Diagnosis and Differential diagnosis

Clinical Diagnosis

1) Three step test

The key for diagnosing SOP is the three-step test, which requires
motility measurements in the primary position, right and left side
gaze, and right and left head tilts. The first step excludes half of the
eight cyclovertical muscles by incriminating the two depressors
of the hypertropic eye and the two elevators of the hypotropic
eye. The second step reduces the four remaining muscles to the
two, whose strongest action is in the field of the greatest side gaze
deviation. The third step selects the remaining muscle that express
elevated weakness when its torsional power is manifested by the
Bielschowsky head-tilt test.6 (Figure 1)

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Superior Oblique Palsy

Figure 1: Three Step test

2) Torsion
Torsion should be assessed in all patients with vertical deviation.

Subjective and objective measurements are available. Subjective
measurements are performed using a double Maddox rod test
(figure2) and synoptophore (figure3), and objective measurements
included fundus examination using fundus photography or optical

44 CME on COMPLEX STRABISMUS