Functional dysphonia - Homepages at WMU

Functional dysphonia

Nelson Roy, PhD, CCC-SLP

Functional dysphonia-a voice disturbance in the absence of Functional dysphonia (FD) refers to a voice disturbance
structural or neurologic laryngeal pathology-is an enigmatic that occurs in the absence of structural or neurologic
and controversial voice disorder that is frequently encountered laryngeal pathological characteristics, and may account
in multidisciplinary voice clinics. Poorly regulated activity of the for 10 to 40% of cases referred to multidisciplinary voice
intrinsic and extrinsic laryngeal muscles is cited as the proximal clinics [1-3]. FD occurs predominantly in women, com­
cause of functional dysphonia, but the origin of this monly follows upper respiratory infection symptoms, is
dyregulated laryngeal muscle activity' has not been fully frequently transient, and varies in its response to treat­
elucidated. Several causes have been cited as contributing to ment [1,4,5J. Functional dysphonia and aphonia are of­
this imbalanced muscle tension; however, recent research ten regarded as disorders on a continuum of severity, and
evidence points to specific personality traits as important are believed by some to share a common cause. In apho­
contributors to its development and maintenance. Voice nia, patients speak in a whisper, whereas dysphonia im­
therapy by an experienced speech-language pathologist plies phonation is preserved, but disordered in quality,
remains an effective short-term treatment for functional pitch, or loudness [6-8].
dysphonia in the majority of cases, but less is known regarding
the long-term fate of such intervention. Further research is The term "functional" implies a voice problem of physi­
needed to better understand the pathogenesis of functional ological function rather than anatomic structure [9-]. In
dysphonia, and factors contributing to its successful clinical circles, "functional" is usually contrasted with
management. Curr Opin Otolaryngol Head Neck Surg 2003, 11: 144-148 "organic" and often carries the added meaning of psy­
© 2003 Lippincott Williams &Wilkins, chogenic [10J. Stress, emotion, and psychologic conflict
are frequently presumed to cause or exacerbate func­
Department of Communication Sciences & Disorders & Division of tional symptoms. Some confusion surrounds the diagnos­
Otolaryngology-Head & Neck Surgery, The University of Utah, Salt Lake City, tic category of "functional dysphonia," because it in­
cludes an assortment of medically unexplained voice
Utah, USA disorders: psychogenic, conversion, hysterical, tension­
fatigue syndrome, hyperfunctional, muscle misuse, or
Correspondence to Nelson Roy, PhD, Department of Communication Sciences & muscle tension dysphonia [11-15]. Although each diag­
Disorders, The University of Utah, 390 South, 1530 East, Room 1219, Salt Lake nostic label implies some degree of etiologic heteroge­
City, UT 84112, USA; e-mail: nelson.roy@health,utah.edu neity, whether these disorders are qualitatively different
and etiologically distinct remains unclear. When applied
Current Opinion in Otolaryngology & Head and Neck Surgery 2003, clinically, these various diagnostic labels often reflect cli­
11 :144-148 nician supposition, bias, or preference. However, at the
purely phenomenological level, there may be few em­
Abbreviations pirically tractable differences that reliably distinguish
FD functional dysphonia these voice disorders.

ISSN 1068-9508 © 2003 Lippincott Williams &Wilkins

More recently, "muscle tension dysphonia" has become
the preferred diagnostic label to describe functional
voice problems presumably related to dysregulated or
imbalanced laryngeal and paralaryngeal muscle activity
[12,16,17J. A variety of glottic and supraglottic contrac­
tion patterns have been associated with muscle tension
dysphonia/FD, and several classification systems have
been offered to describe these laryngoscopic features
[16,18,19J. Often-cited laryngeal manifestations of dys­
regulated laryngeal muscle tension include the follow­
ing: tight mediolateral glottic and/or supraglottic contrac­
tion, anteroposterior glottic and/or supraglottic
compression, incomplete glottic closure, posterior glottic
chink, and bowing [15,16,19]. However, researchers have
recently challenged the existence of specific Iaryngo­

144

Functional dysphonia Roy 145

scopic clusters/features that uniquely and reliably distin­ ested reader is referred to Roy and Bless [28-] for a more
guish FD from nondysphonic speakers, and other voice complete exploration of the putative psychologic and
disorder types including spasmodic dysphonia [9,20-,21]. personality processes involved in FD, as well as related
Many of the laryngoscopic patterns used to classify FD research.
are frequently observed in individuals with normal
voices and spasmodic dysphonia, and thus fail to distin­ Recently, a theory has been proposed to link specific
guish such individuals from patients with FD [9,21]. personality traits to the development of FD [28-,41-].
Given the likely involvement of a variety of intrinsic and The "Trait theory of FD" emphasized a theme of in­
extrinsic laryngeal muscles-in diverse states of relax­ hibitory laryngeal behavior, but attributed this muscu­
ation and contraction-myriad laryngeal configurations larly inhibited voice production to specific personality
may be present in FD [22]. typologies. In brief, the authors speculated that the com­
bination of personality traits, such as introversion and
Although poorly regulated activity of the intrinsic and neuroticism (trait anxiety), contributes to predictable
extrinsic laryngeal muscles is cited as the proximal cause and conditioned laryngeal inhibitory responses to certain
of muscle tension dysphonia, the origin of this muscle environmental signals/cues. For instance, when undesir­
activity has not been fully elucidated. It has been attrib­ able punishing or frustrating outcomes have been paired
uted to a variety of sources, including (1) technical mis­ with previous attempts to speak out, Roy and Bless pos­
uses of the vocal mechanism in the context of extraordi­ tulated that this might lead to muscularly inhibited voice
nary voice demands [11-13,15], (2) learned adaptations production in individuals predisposed by specific person­
after upper respiratory tract infection [14,23], (3) in­ ality characteristics. The authors contended that this
creased pharyngolaryngeal tone secondary to the laryn­ conflict between laryngeal inhibition and activation (that
gopharyngeal reflux reflex [18], (4) extreme compensa­ has its origins in personality and nervous system func­
tion for minor glottic insufficiency and/or underlying tioning), results in elevated laryngeal tension states and
mucosal disease [24], and (5) psychologic and/or person­ can give rise to incomplete or disordered vocalization in
ality factors that tend to induce elevated tension in the a structurally and neurologically intact larynx.
laryngeal region [7,25-28-].
In research designed to test the theory and assess wheth­
Psychologic factors in er personality factors play causal, concomitant, or conse­
functional dysphonia quential roles in common voice disorders, Roy and col­
A wide array of psychopathologic processes contributing leagues [34",35"] compared a vocally normal control
to voice symptom formation in FD has been proposed group and four groups with voice disorders-FD, vocal
[27,29]. The exquisite sensitivity and prolonged hyper­ nodules, spasmodic dysphonia, and unilateral vocal fold
contraction of the intrinsic and extrinsic laryngeal paralysis-using The Eysenck Personality Question­
muscles, in response to stress, conflict, anxiety, depres­ naire. The Eysenck Personality Questionnaire-a popu­
sion, or inhibited emotional expression, is frequently lar personality assessment tool-generates scores for the
cited as the common denominator underlying the major­ personality superfactors: extraversion and neuroticism.
ity of functional voice problems [7,30]. Other possible Extraversion involves the willingness to engage and con­
mechanisms include, but are not limited to, conversion front the environment, including the social environment.
reaction, hysteria, hypochondriasis, and various situ­ Extraverts (high extraversion) tend to be dominant, so­
ational conflicts or personality dispositions that also in­ ciable, and active, whereas introverts (low extraversion)
duce excess or dysregulated laryngeal musculoskeletal tend to be quiet, unsociable, passive, and careful. Neu­
tension [6,25,26,28]. However, research evidence to sup­ roticism, the second personality dimension, can be lik­
port these various psychologic mechanisms has seldom ened to emotionality and is related to anxious, de­
been provided. The empirical literature evaluating the pressed, tense, and emotional characteristics. High
FD-psychology relationship is characterized by diver­ neuroticism individuals tend to be emotionally unstable,
gent results regarding the frequency and degree of spe­ worried, and highly reactive to environmental stimuli
cific personality traits [6,31-34",35"], conversion reac­ [34"]. The results showed that distinct personality char­
tion [6,36], and psychopathologic symptoms such as acteristics were present \vithin the FD and vocal nodules
depression and anxiety [6,31,34-,35-40]. Despite signifi­ groups, and were conspicuously absent in the other
cant methodologic differences among these studies, groups. Group comparisons revealed that the majority of
some interesting patterns do surface. These patterns FD and vocal nodules subjects were classified as intro­
suggest a general trend tmvard elevated levels of (1) state verts and extraverts, respectively. As compared to the
and trait anxiety, (2) depression, (3) somatic preoccu­ other groups, the FD group scored significantly higher
pation/complaints, and (4) introversion in the FD popu­ on the neuroticism dimension, thereby providing robust
lation. Patients have been described as inhibited, stress evidence to support the role of elevated neuroticism in
reactive, socially anxious, and nonassertive, with a ten­ FD development. Comparisons involving the spasmodic
dency toward restraint [31,33,34,35",36]. The inter- dysphonia, unilateral vocal fold paralysis, and control

----------------_.­

146 Speech therapy and rehabilitation

subjects did not identify any consistent personality dif­ period. Based on perceptual ratings, 96% of patients
ferences. On the whole, these differences in personality were rated as improved, with almost two thirds of all
were compatible with the predictions of the Trait patients achieving normal voice return after the single
Theory of the dispositional bases of FD. In contrast, the treatment session.
disability hypothesis, which suggests that personality
features and emotional maladjustment are solely a nega­ The hypothesized physical effect of such circumlaryn­
tive consequence of vocal disability, was not supported. geal massage is reduced laryngeal height and stiffness
The investigators concluded that the results largely sup­ and increased mobility. Once the larynx is "re­
port the contention that individuals with certain person­ leased/lowered" and range of motion is normalized, an
ality traits may be susceptible to developing FD improvement in vocal effort, quality, and dynamic range
[34",35"]. should follow. Roy and Ferguson [46-] combined knowl­
edge of the source-filter theory of vowel production with
Management of functional dysphonia formant frequency analysis to indirectly assess changes
in vocal tract length after successful manual circumlaryn­
Despite considerable controversy surrounding causal geal therapy with 75 subjects with FD. The "length
mechanisms, the clinical voice literature is replete with rule" of the source-filter theorv states that the average
evidence that symptomatic voice therapy for functional frequencies of the vowel formants (local resonances in
voice disorders can often result in rapid and dramatic the vocal tract) are inversely proportional to the length of
voice improvement [4,7,10,15,21,42-46-,47-50]. the pharyngeal-oral tract. In short, as the vocal tract in­
creases in length, the average formant frequencies lower.
Because excess or dysregulatedlaryngeal muscle tension Therefore, laryngeal elevation should shorten the verti­
is frequently offered as the cause of FD, many voice cal dimension of the pharynx, whereas lowering of the
therapies including yawn-sigh, resonant voice therapy, larynx should result in lengthening of the pharyngeal­
visual and electromyographic biofeedback, progressive oral tract. Therefore, a shorter vocal tract creates el­
relaxation, and circumlaryngeal massage aim to reduce or evated formant frequencies; alternatively, a longer tract
rebalance such tension [7,48]. Prolonged hypercontrac­ produces lmver formants. These investigators reported
tion of laryngeal muscles is often associated with eleva­ significant lowering of the first three formant frequencies
tion of the larynx and hyoid bone, with associated pain of the vowel /a/ after voice improvement. These findings
and discomfort when the circumlaryngeal region is pal­ were compatible with a decrease in laryngeal height and
pated [5,22,51]. Several voice clinicians have described lengthening of the vocal tract as predicted by the source­
manual/digital techniques to determine the presence and filter theory, and provide corroborating evidence for
degree of laryngeal musculoskeletal tension, as well as Aronson's [7] contention that voice improvement after
methods to relieve such tension during the diagnostic manual circumlaryngeal therapy for FD may be associ­
assessment and management session [7,22,51-53]. Aron­ ated with lowered laryngeal position.
son [7] speculated that therapy failure for muscle tension
voice disorders may be caused, at least in part, by tech­ Certainly, direct symptomatic therapy for FD can pro­
niques that do not yield sufficient laryngeal tension re­ duce rapid voice changes; however, in some cases, voice
duction. He offered that indirect (ie, nonmanual) tension therapy can be a frustrating and protracted experience
reduction techniques often fail because of the stubborn for both clinician and patient [1,53,54]. Because there are
nature of excess larvngeal musculoskeletal tension. In­ few studies directly comparing the effectiveness of spe­
stead, Aronson offered circumlaryngeal massage as a di­ cific therapy techniques, not much is known about
rect method to induce laryngeal tension reduction. Skill­ whether one therapy approach for FD is superior to an­
fully applied, systematic kneading of the extralaryngeal other. According to most sources, signs of voice improve­
region is believed to stretch muscle tissue and fascia, ment should typically be observed within the first voice
promote local circulation with removal of metabolic therapy session; however some patients may require an
wastes, relax tense muscles, and relieve pain and discom­ extended, intensive treatment session or several ses­
fort associated with muscle spasms [22]. sions, depending on a number of variables including the
therapy technique(s) selected, clinician experience and
In a series of investigations, Roy and colleagues have confidence in administering the approach, and patient
evaluated the clinical utility of manual techniques with a motivation and tolerance. In cases of FD that are unre­
variety of functional voice disorders [4,5,17,24]. Roy {'f al. sponsive or resistant to standard voice therapy, Dworkin
[5] reported the immediate and long-term effects of et al. [55-] recently reported the use of transcricothyroid
manual circumlaryngeal therapy for 25 female patients membrane lidocaine injection to successfully interrupt
with FD. Perceptual, acoustic, and interview techniques hyperactive glottal and supraglottal muscle contraction
were used to assess vocal function before and after treat­ patterns observed in three patients with refractory
ment. Subjects demonstrated consistent improvement muscle tension dysphonia/FD. When the lidocaine in­
across perceptual and acoustic indices of vocal function jection was followed by several minutes of voice therapy,
immediately after treatment and during the follow-up

Functional dysphonia Roy 147

all three previously unresponsive patients experienced References and recommended reading
prompt and sustained voice improvement. The exact
mechanism underlying the positive result remains uncer­ Papers of particular interest, published with the annual period of review. have
tain; however, the authors h'ypothesize that the topical been highlighted as:
lidocaine bath acts on the mucosal mechanoreceptors of
the laryngeal inlet, interrupting sensorv feedback during Of special interest
phonation, and breaking the cycle of hyperfunctional vo­
cal fold contraction that contributes to the dysphonia. Of outstanding interest
Whether this procedure is best administered after tradi­
tional voice therapy has failed, or before voice therapy is Bridger MM, Epstein R: Functional voice disorders: a review of 109 patients.
offered, requires further investigation. J Laryngol Otol 1983.97:1145-1148.

The long-term effectiveness of direct voice therapy for 2 Koufman JA, Blalock PO: Functional voice disorders. Otolaryngol Clin North
functional voice disorders also has not been rigorously Am 1991,4:1059-1073.
evaluated [48,49]. Of the few investigations that exist,
the results regarding the durability of voice improvement 3 Schalen L. Andersson K: Differential diagnosis and treatment of psychogenic
after direct therapy for FD are mixed [5,10,42,44]. It voice disorder. Clin Otolaryngol 1992, 17:225-230.
should be acknowledged that after direct voice therapy,
only the voice symptom has been removed, not the un­ 4 Roy N, Leeper HA: Effects of the manual laryngeal musculoskeletal tension
derlying cause of the disturbance itself [26,32,37]. reduction technique as a treatment for functional voice disorders: perceptual
Therefore, the nature of precipitating and perpetuating and acoustic measures. J Voice 1993, 7:242-249.
factors, including possible psychologic dysfunction,
needs to be better understood. If the situational, emo­ 5 Roy N, Bless OM, Heisey 0, et al.: Manual circum laryngeal therapy for func­
tional, or personality features that contributed to the de­ tional dysphonia: an evaluation of short- and long-term treatment outcomes.
velopment of the voice disorder remain unchanged after J Voice 1997, 11 :321-331.
behavioral treatment, it would be logical to expect that
such persistent factors would increase the probabil­ 6 Aronson AE, Peterson HW, Litin EM: Psychiatric symptomatology in func­
ity/risk of future recurrences [35",42,56]. Therefore, in tional dysphonia and aphonia. J Speech Hear Dis 1966,31 :115-127.
some cases, posttreatment referral to a psychiatrist or
psychologist may be necessary to achieve more enduring 7 Aronson AE: Clinical Voice Disorders: An Interdisciplinary Approach, edn 3.
improvements in the patient's emotional/life adjustment New York: Thieme, 1990.
and voice function [26,54,56]. This is especially appro­
priate in cases where dysphonic relapses are frequent 8 Boone DR, McFarlane SC: The Voice and Voice Therapy, edn 6. Englewood
and protracted. Cliffs, NJ: Prentice Hall, 2000.

Conclusions 9 Sama A, Carding PN, Price S, et al.: The clinical features of functional dys­
phonia. Laryngoscope 2001. 111 :458-463.
Functional dysphonia-a VOIce disturbance in the ab­
sence of structural or neurologic laryngeal pathological This well-designed research article questions the clinical utility and validity of laryn­
factors-is an enigmatic and controversial voice disorder goscopic classification systems of FD. The laryngoscopic features commonly as­
that is frequently encountered in multidisciplinary voice sociated with FD are frequently prevalent in nondysphonic controls and fail to dis­
clinics. Recently, the term FD has been replaced in tinguish subjects with FD from normal subjects.
some clinical circles by the diagnostic label "muscle ten­
sion dysphonia," which serves to highlight excess, dvs­ 10 Carding P, Horsley I, Docherty G: A study of the effectiveness of voice
regulated, or imbalanced activity of the intrinsic and ex­ therapy in the treatment of 45 patients with non organic dysphonia. J Voice
trinsic laryngeal muscles as the proximal cause of the 1999,13:72-104.
observed dysphonia. Although many sources have been
cited as contributing to this muscle tension, specific per­ 11 Morrison MD, Nichol H, Rammage LA: Diagnostic criteria in functional dys­
sonality traits have been identified as important to its phonia. Laryngoscope 1986, 94:1-8.
development and maintenance. Voice therapy by an ex­
perienced speech-language pathologist remains an efIec­ 12 Morrison MD, Rammage LA, Gilles MB, et al.: Muscular tension dysphonia.
tive short-term treatment for FD in the majority of cases, J Otolaryngol 1983, 12:302-306.
but little is known regarding the long-term fate of such
treatment. Further research is needed to better under­ 13 Morrison MD, Rammage L: Muscle misuse voice disorders: description and
stand the pathogenesis of FD, and factors contributing to classification. Acta Otolaryngol (Stockh) 1993, 113:428-434.
its successful management.
14 Koufman JA, Blalock PO: Classification and approach to patients with func­
tional voice disorders. Ann Otol Rhinol Laryngol1982, 91 :372-377.

15 Koufman JA, Blalock PO: Vocal fatigue and dysphonia in the professional
voice user: Bogart-Bacall syndrome. Laryngoscope 1988, 98:493-499.

16 Morrison MD, Rammage LA: The Management of Voice Disorders. San
Diego: Singular Publishing Group, 1994.

17 Roy N, Ford CN, Bless OM: Muscle tension dysphonia and spasmodic dys­
phonia: the role of manual laryngeal tension reduction in diagnosis and treat­
ment. Ann Otol Rhinol Laryngol1996, 105:851-856.

18 Morrison MO: Pattern recognition in muscle misuse voice disorders: how I do
it. J Voice 1997, 11:108-114.

19 Lawrence VL: Suggested criteria for fibre-optic diagnosis of vocal hyperfunc­
tion. In Care of the Professional Voice Symposium. London: The British Voice
Association; 1987.

20 Schneider B, Wendler J, Seidner W: The relevance of stroboscopy in func­
tional dysphonias. Folia Phoniatr Logop 2002,54:44-54.

These researchers failed to find stroboscopic evidence (correlates) of subtypes of
FD (ie, hyperfunctional vs. hypofunctional), nor did they identify any separate laryn­
gostroboscopic clusters to warrant subtyping of FD.

21 Leonard R, Kendall R: Differentiation of spasmodic and psychogenic dyspho­
nlas with phonoscopic evaluation. Laryngoscope 1999, 109:295-300.

22 Roy N, Bless OM: Manual circum laryngeal techniques in the assessment and
treatment of voice disorders. Curr Opin Otolaryngol Head Neck Surg 1998,
6:151-155.

23 Milutinovic Z: Inflammatory changes as a risk factor in the development of
phononeurosis. Folia Phoniatr 1991,43:177-180.

24 Roy N: Ventricular dysphonia following long-term endotracheal intubation: a
case study. J Otolaryngol1994, 23:189-193.

25 Butcher P: Psychological processes in psychogenic voice disorder. Eur J Dis
Commun 1995.30:467-474.

148 Speech therapy and rehabilitation 41 Roy N, Bless OM: Personality traits and psychological factors in voice pathol­
ogy: a foundation for future research. J Speech Lang Hear Res 2000,
26 Butcher P, Elias A, Raven R: Psychogenic Voice Disorders and Cognitive 43:737-748.
Behaviour Therapy. San Diego: Singular Publishing Group; 1993.
This article provides a cursory review of the literature (circa 1998) pertaining to the
27 Rammage LA, Nichol H, Morrison MD: The psychopathology of voice disor­ FD-psychology relationship. The fundamental tenets and predictions of the trait
ders. Hum Commun Can 1987,11 :21-25. theory are outlined.

28 Roy N, Bless OM: Toward a theory of the dispositional bases of functional 42 Andersson K, Schalen L: Etiology and treatment of psychogenic voice disor­
dysphonia and vocal nodules: exploring the role of personality and emotional der: results of a follow-up study of thirty patients. J Voice 1998, 12:96-106.
adjustment. In Voice Ouality Measurement. Edited by Kent RD, Ball MJ. San
Diego: Singular Publishing Group, 2000:461-480. 43 Carding P, Horsley I: An evaluation study of voice therapy in non-organic
dysphonia. Eur J Dis Commun 1992, 27:137-158.
The relevant literature that explores possible psychopathological process in FD,
vocal nodules, and spasmodic dysphonia is reviewed. In addition, a complete ex­ 44 Gunther V, Mayr-Graft A, Miller C, et al.: A comparative study of psychological
plication of the Trait Theory of FD is provided along with its key mechanistic asser­ aspects of recurring and non-recurring functional aphonias. Eur Arch Otorhi­
tions. nolaryngol 1996, 253:240-244.

29 Green G: The inter-relationship between vocal and psychological character­ 45 Milutinovic Z: Results of vocal therapy for phononeurosis: behavior approach.
istics: a literature review. Aust J Hum Commun Dis 1988, 16:31-43. Folia Phoniatr 1990, 42:173-177.

30 House AO, Andrews HB: Life events and difficulties preceding the onset of 46 Roy N, Ferguson NA: Formant frequency changes following manual circum­
functional dysphonia. J Psychosom Res 1988, 32:311-319. laryngeal therapy for functional dysphonia: evidence of laryngeal lowering?
J Med Speech Lang Pathol 2001,9:169-175.
31 Gerritsma EJ: An investigation into some personality characteristics of pa­
tients with psychogenic aphonia and dysphonia. Folia Phoniatr 1991, These investigators used acoustic theory and analysis to assess the "laryngeal
43:13-20. lowering hypothesis" to explain voice improvement in FD after successful manual
circumlaryngeal therapy. Results from formant frequency analysis provided indirect
32 Kinzl J, Biebl W, Rauchegger H: Functional aphonia: psychosomatic aspects support for Aronson's contention that the larynx lowers after circumlaryngeal mas­
of diagnosis and therapy. Folia Phoniatr 1988, 40:131-137. sage.

33 Friedl W, Friedrich G, Egger J: Personality and coping with stress in patients 47 Stemple J: Voice Therapy: Clinical Studies, 2nd edn. San Diego: Singular
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34 Roy N, Bless OM, Heisey 0: Personality and voice disorders: a superfactor 48 Ramig La, Verdolini K: Treatment efficacy: voice disorders. J Speech Lang
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of voice disorders and a non-voice-disordered control in this well·controlled study. for outcome studies. Am J Speech Lang Pathol 1998, 7:49-64.
The results are discussed within the context of the Trait theory of FD.
50 Lieberman J: Principles and techniques of manual therapy: application in the
35 Roy N, Bless OM, Heisey 0: Personality and voice disorders: a multitrait­ management of dysphonia. In The Voice Clinical Handbook. Edited by Harris
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superfactor trait level of analysis. 1991,11 :209-215.

36 Roy N, McGrory JJ, Tasko SM, et al: Psychological correlates of functional 53 Fex F, Fex S, Shiromoto 0, et al.: Acoustic analysis of functional dysphonia:
dysphonia: an evaluation using the Minnesota Multiphasic Personality Inven­ before and after voice therapy (accent method). J Voice 1994, 8:163-167.
tory. J Voice 1997, 11 :443-451.
54 Butcher P, Elias A, Raven R, et al.: Psychogenic voice disorder unresponsive
37 Deary IJ, Scott S, Wilson 1M, et al.: Personality and psychological distress in to speech therapy: psychological characteristics and cognitive-behaviour
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38 Pfau EM: Psychological factors underlying the etiology of psychogenic dys­ 55 Dworkin JP, Meleca RJ, Simpson ML, et al.: Use of topical lidocaine in the
phonia. Folia Phoniatr 1975, 25:298-306. treatment of muscle tension dysphonia. J Voice 2000, 14:567-574.

39 White A, Deary IJ, Wilson JA: Psychiatric disturbance and personality traits in A novel approach for treating refractory cases of muscle tension dysphonia is
dysphonic patients. Eur J Dis Commun 1997, 32:121-128. described.

40 Friedl W, Friedrich G, Egger J, et al.: Psychogenic aspects of functional dys­ 56 Nichol H, Morrison MD, Rammage LA: Interdisciplinary approach to func­
phonia. Folia Phoniatr 1993, 45:10-13. tional voice disorders: the psychiatrist's role. Otolaryngol Head Neck Surg
1993,108:643-647.