Document 6479227

Functional dysphonia
Nelson Roy, PhD, CCC-SLP
Functional dysphonia-a voice disturbance in the absence of
structural or neurologic laryngeal pathology-is an enigmatic
and controversial voice disorder that is frequently encountered
in multidisciplinary voice clinics. Poorly regulated activity of the
intrinsic and extrinsic laryngeal muscles is cited as the proximal
cause of functional dysphonia, but the origin of this
dyregulated laryngeal muscle activity' has not been fully
elucidated. Several causes have been cited as contributing to
this imbalanced muscle tension; however, recent research
evidence points to specific personality traits as important
contributors to its development and maintenance. Voice
therapy by an experienced speech-language pathologist
remains an effective short-term treatment for functional
dysphonia in the majority of cases, but less is known regarding
the long-term fate of such intervention. Further research is
needed to better understand the pathogenesis of functional
dysphonia, and factors contributing to its successful
management. Curr Opin Otolaryngol Head Neck Surg 2003, 11: 144-148
© 2003 Lippincott Williams & Wilkins,
Department of Communication Sciences & Disorders & Division of
Otolaryngology-Head & Neck Surgery, The University of Utah, Salt Lake City,
Utah, USA
Correspondence to Nelson Roy, PhD, Department of Communication Sciences &
Disorders, The University of Utah, 390 South, 1530 East, Room 1219, Salt Lake
City, UT 84112, USA; e-mail: nelson.roy@health,utah.edu
Current Opinion in Otolaryngology & Head and Neck Surgery 2003,
11 :144-148
Abbreviations
FD
functional dysphonia
ISSN 1068-9508 © 2003 Lippincott Williams & Wilkins
Functional dysphonia (FD) refers to a voice disturbance
that occurs in the absence of structural or neurologic
laryngeal pathological characteristics, and may account
for 10 to 40% of cases referred to multidisciplinary voice
clinics [1-3]. FD occurs predominantly in women, com­
monly follows upper respiratory infection symptoms, is
frequently transient, and varies in its response to treat­
ment [1,4,5J. Functional dysphonia and aphonia are of­
ten regarded as disorders on a continuum of severity, and
are believed by some to share a common cause. In apho­
nia, patients speak in a whisper, whereas dysphonia im­
plies phonation is preserved, but disordered in quality,
pitch, or loudness [6-8].
The term "functional" implies a voice problem of physi­
ological function rather than anatomic structure [9-]. In
clinical circles, "functional" is usually contrasted with
"organic" and often carries the added meaning of psy­
chogenic [10J. Stress, emotion, and psychologic conflict
are frequently presumed to cause or exacerbate func­
tional symptoms. Some confusion surrounds the diagnos­
tic category of "functional dysphonia," because it in­
cludes an assortment of medically unexplained voice
disorders: psychogenic, conversion, hysterical, tension­
fatigue syndrome, hyperfunctional, muscle misuse, or
muscle tension dysphonia [11-15]. Although each diag­
nostic label implies some degree of etiologic heteroge­
neity, whether these disorders are qualitatively different
and etiologically distinct remains unclear. When applied
clinically, these various diagnostic labels often reflect cli­
nician supposition, bias, or preference. However, at the
purely phenomenological level, there may be few em­
pirically tractable differences that reliably distinguish
these voice disorders.
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
guish FD from nondysphonic speakers, and other voice
disorder types including spasmodic dysphonia [9,20-,21].
Many of the laryngoscopic patterns used to classify FD
are frequently observed in individuals with normal
voices and spasmodic dysphonia, and thus fail to distin­
guish such individuals from patients with FD [9,21].
Given the likely involvement of a variety of intrinsic and
extrinsic laryngeal muscles-in diverse states of relax­
ation and contraction-myriad laryngeal configurations
may be present in FD [22].
Although poorly regulated activity of the intrinsic and
extrinsic laryngeal muscles is cited as the proximal cause
of muscle tension dysphonia, the origin of this muscle
activity has not been fully elucidated. It has been attrib­
uted to a variety of sources, including (1) technical mis­
uses of the vocal mechanism in the context of extraordi­
nary voice demands [11-13,15], (2) learned adaptations
after upper respiratory tract infection [14,23], (3) in­
creased pharyngolaryngeal tone secondary to the laryn­
gopharyngeal reflux reflex [18], (4) extreme compensa­
tion for minor glottic insufficiency and/or underlying
mucosal disease [24], and (5) psychologic and/or person­
ality factors that tend to induce elevated tension in the
laryngeal region [7,25-28-].
Psychologic factors in
functional dysphonia
A wide array of psychopathologic processes contributing
to voice symptom formation in FD has been proposed
[27,29]. The exquisite sensitivity and prolonged hyper­
contraction of the intrinsic and extrinsic laryngeal
muscles, in response to stress, conflict, anxiety, depres­
sion, or inhibited emotional expression, is frequently
cited as the common denominator underlying the major­
ity of functional voice problems [7,30]. Other possible
mechanisms include, but are not limited to, conversion
reaction, hysteria, hypochondriasis, and various situ­
ational conflicts or personality dispositions that also in­
duce excess or dysregulated laryngeal musculoskeletal
tension [6,25,26,28]. However, research evidence to sup­
port these various psychologic mechanisms has seldom
been provided. The empirical literature evaluating the
FD-psychology relationship is characterized by diver­
gent results regarding the frequency and degree of spe­
cific personality traits [6,31-34",35"], conversion reac­
tion [6,36], and psychopathologic symptoms such as
depression and anxiety [6,31,34-,35-40]. Despite signifi­
cant methodologic differences among these studies,
some interesting patterns do surface. These patterns
suggest a general trend tmvard elevated levels of (1) state
and trait anxiety, (2) depression, (3) somatic preoccu­
pation/complaints, and (4) introversion in the FD popu­
lation. Patients have been described as inhibited, stress
reactive, socially anxious, and nonassertive, with a ten­
dency toward restraint [31,33,34,35",36]. The inter-
ested reader is referred to Roy and Bless [28-] for a more
complete exploration of the putative psychologic and
personality processes involved in FD, as well as related
research.
Recently, a theory has been proposed to link specific
personality traits to the development of FD [28-,41-].
The "Trait theory of FD" emphasized a theme of in­
hibitory laryngeal behavior, but attributed this muscu­
larly inhibited voice production to specific personality
typologies. In brief, the authors speculated that the com­
bination of personality traits, such as introversion and
neuroticism (trait anxiety), contributes to predictable
and conditioned laryngeal inhibitory responses to certain
environmental signals/cues. For instance, when undesir­
able punishing or frustrating outcomes have been paired
with previous attempts to speak out, Roy and Bless pos­
tulated that this might lead to muscularly inhibited voice
production in individuals predisposed by specific person­
ality characteristics. The authors contended that this
conflict between laryngeal inhibition and activation (that
has its origins in personality and nervous system func­
tioning), results in elevated laryngeal tension states and
can give rise to incomplete or disordered vocalization in
a structurally and neurologically intact larynx.
In research designed to test the theory and assess wheth­
er personality factors play causal, concomitant, or conse­
quential roles in common voice disorders, Roy and col­
leagues [34",35"] compared a vocally normal control
group and four groups with voice disorders-FD, vocal
nodules, spasmodic dysphonia, and unilateral vocal fold
paralysis-using The Eysenck Personality Question­
naire. The Eysenck Personality Questionnaire-a popu­
lar personality assessment tool-generates scores for the
personality superfactors: extraversion and neuroticism.
Extraversion involves the willingness to engage and con­
front the environment, including the social environment.
Extraverts (high extraversion) tend to be dominant, so­
ciable, and active, whereas introverts (low extraversion)
tend to be quiet, unsociable, passive, and careful. Neu­
roticism, the second personality dimension, can be lik­
ened to emotionality and is related to anxious, de­
pressed, tense, and emotional characteristics. High
neuroticism individuals tend to be emotionally unstable,
worried, and highly reactive to environmental stimuli
[34"]. The results showed that distinct personali ty char­
acteristics were present \vithin the FD and vocal nodules
groups, and were conspicuously absent in the other
groups. Group comparisons revealed that the majority of
FD and vocal nodules subjects were classified as intro­
verts and extraverts, respectively. As compared to the
other groups, the FD group scored significantly higher
on the neuroticism dimension, thereby providing robust
evidence to support the role of elevated neuroticism in
FD development. Comparisons involving the spasmodic
dysphonia, unilateral vocal fold paralysis, and control
----------------_.­
146 Speech therapy and rehabilitation
subjects did not identify any consistent personality dif­
ferences. On the whole, these differences in personality
were compatible with the predictions of the Trait
Theory of the dispositional bases of FD. In contrast, the
disability hypothesis, which suggests that personality
features and emotional maladjustment are solely a nega­
tive consequence of vocal disability, was not supported.
The investigators concluded that the results largely sup­
port the contention that individuals with certain person­
ality traits may be susceptible to developing FD
[34",35"].
Management of functional dysphonia
Despite considerable controversy surrounding causal
mechanisms, the clinical voice literature is replete with
evidence that symptomatic voice therapy for functional
voice disorders can often result in rapid and dramatic
voice improvement [4,7,10,15,21,42-46-,47-50].
Because excess or dysregulatedlaryngeal muscle tension
is frequently offered as the cause of FD, many voice
therapies including yawn-sigh, resonant voice therapy,
visual and electromyographic biofeedback, progressive
relaxation, and circumlaryngeal massage aim to reduce or
rebalance such tension [7,48]. Prolonged hypercontrac­
tion of laryngeal muscles is often associated with eleva­
tion of the larynx and hyoid bone, with associated pain
and discomfort when the circumlaryngeal region is pal­
pated [5,22,51]. Several voice clinicians have described
manual/digital techniques to determine the presence and
degree of laryngeal musculoskeletal tension, as well as
methods to relieve such tension during the diagnostic
assessment and management session [7,22,51-53]. Aron­
son [7] speculated that therapy failure for muscle tension
voice disorders may be caused, at least in part, by tech­
niques that do not yield sufficient laryngeal tension re­
duction. He offered that indirect (ie, nonmanual) tension
reduction techniques often fail because of the stubborn
nature of excess larvngeal musculoskeletal tension. In­
stead, Aronson offered circumlaryngeal massage as a di­
rect method to induce laryngeal tension reduction. Skill­
fully applied, systematic kneading of the extralaryngeal
region is believed to stretch muscle tissue and fascia,
promote local circulation with removal of metabolic
wastes, relax tense muscles, and relieve pain and discom­
fort associated with muscle spasms [22].
In a series of investigations, Roy and colleagues have
evaluated the clinical utility of manual techniques with a
variety of functional voice disorders [4,5,17,24]. Roy {'f al.
[5] reported the immediate and long-term effects of
manual circumlaryngeal therapy for 25 female patients
with FD. Perceptual, acoustic, and interview techniques
were used to assess vocal function before and after treat­
ment. Subjects demonstrated consistent improvement
across perceptual and acoustic indices of vocal function
immediately after treatment and during the follow-up
period. Based on perceptual ratings, 96% of patients
were rated as improved, with almost two thirds of all
patients achieving normal voice return after the single
treatment session.
The hypothesized physical effect of such circumlaryn­
geal massage is reduced laryngeal height and stiffness
and increased mobility. Once the larynx is "re­
leased/lowered" and range of motion is normalized, an
improvement in vocal effort, quality, and dynamic range
should follow. Roy and Ferguson [46-] combined knowl­
edge of the source-filter theory of vowel production with
formant frequency analysis to indirectly assess changes
in vocal tract length after successful manual circumlaryn­
geal therapy with 75 subjects with FD. The "length
rule" of the source-filter theorv states that the average
frequencies of the vowel formants (local resonances in
the vocal tract) are inversely proportional to the length of
the pharyngeal-oral tract. In short, as the vocal tract in­
creases in length, the average formant frequencies lower.
Therefore, laryngeal elevation should shorten the verti­
cal dimension of the pharynx, whereas lowering of the
larynx should result in lengthening of the pharyngeal­
oral tract. Therefore, a shorter vocal tract creates el­
evated formant frequencies; alternatively, a longer tract
produces lmver formants. These investigators reported
significant lowering of the first three formant frequencies
of the vowel /a/ after voice improvement. These findings
were compatible with a decrease in laryngeal height and
lengthening of the vocal tract as predicted by the source­
filter theory, and provide corroborating evidence for
Aronson's [7] contention that voice improvement after
manual circumlaryngeal therapy for FD may be associ­
ated with lowered laryngeal position.
Certainly, direct symptomatic therapy for FD can pro­
duce rapid voice changes; however, in some cases, voice
therapy can be a frustrating and protracted experience
for both clinician and patient [1,53,54]. Because there are
few studies directly comparing the effectiveness of spe­
cific therapy techniques, not much is known about
whether one therapy approach for FD is superior to an­
other. According to most sources, signs of voice improve­
ment should typically be observed within the first voice
therapy session; however some patients may require an
extended, intensive treatment session or several ses­
sions, depending on a number of variables including the
therapy technique(s) selected, clinician experience and
confidence in administering the approach, and patient
motivation and tolerance. In cases of FD that are unre­
sponsive or resistant to standard voice therapy, Dworkin
et al. [55-] recently reported the use of transcricothyroid
membrane lidocaine injection to successfully interrupt
hyperactive glottal and supraglottal muscle contraction
patterns observed in three patients with refractory
muscle tension dysphonia/FD. When the lidocaine in­
jection was followed by several minutes of voice therapy,
Functional dysphonia Roy 147
all three previously unresponsive patients experienced
prompt and sustained voice improvement. The exact
mechanism underlying the positive result remains uncer­
tain; however, the authors h'ypothesize that the topical
lidocaine bath acts on the mucosal mechanoreceptors of
the laryngeal inlet, interrupting sensorv feedback during
phonation, and breaking the cycle of hyperfunctional vo­
cal fold contraction that contributes to the dysphonia.
Whether this procedure is best administered after tradi­
tional voice therapy has failed, or before voice therapy is
offered, requires further investigation.
The long-term effectiveness of direct voice therapy for
functional voice disorders also has not been rigorously
evaluated [48,49]. Of the few investigations that exist,
the results regarding the durability of voice improvement
after direct therapy for FD are mixed [5,10,42,44]. It
should be acknowledged that after direct voice therapy,
only the voice symptom has been removed, not the un­
derlying cause of the disturbance itself [26,32,37].
Therefore, the nature of precipitating and perpetuating
factors, including possible psychologic dysfunction,
needs to be better understood. If the situational, emo­
tional, or personality features that contributed to the de­
velopment of the voice disorder remain unchanged after
behavioral treatment, it would be logical to expect that
such persistent factors would increase the probabil­
ity/risk of future recurrences [35",42,56]. Therefore, in
some cases, posttreatment referral to a psychiatrist or
psychologist may be necessary to achieve more enduring
improvements in the patient's emotional/life adjustment
and voice function [26,54,56]. This is especially appro­
priate in cases where dysphonic relapses are frequent
and protracted.
References and recommended reading
Papers of particular interest, published with the annual period of review. have
been highlighted as:
Of special interest
Of outstanding interest
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Conclusions
Functional dysphonia-a VOIce disturbance in the ab­
sence of structural or neurologic laryngeal pathological
factors-is an enigmatic and controversial voice disorder
that is frequently encountered in multidisciplinary voice
clinics. Recently, the term FD has been replaced in
some clinical circles by the diagnostic label "muscle ten­
sion dysphonia," which serves to highlight excess, dvs­
regulated, or imbalanced activity of the intrinsic and ex­
trinsic laryngeal muscles as the proximal cause of the
observed dysphonia. Although many sources have been
cited as contributing to this muscle tension, specific per­
sonality traits have been identified as important to its
development and maintenance. Voice therapy by an ex­
perienced speech-language pathologist remains an efIec­
tive short-term treatment for FD in the majority of cases,
but little is known regarding the long-term fate of such
treatment. Further research is needed to better under­
stand the pathogenesis of FD, and factors contributing to
its successful management.
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
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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.
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dysphonia and vocal nodules: exploring the role of personality and emotional
adjustment. In Voice Ouality Measurement. Edited by Kent RD, Ball MJ. San
Diego: Singular Publishing Group, 2000:461-480.
The relevant literature that explores possible psychopathological process in FD,
vocal nodules, and spasmodic dysphonia is reviewed. In addition, a complete ex­
plication of the Trait Theory of FD is provided along with its key mechanistic asser­
41
Roy N, Bless OM: Personality traits and psychological factors in voice pathol­
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This article provides a cursory review of the literature (circa 1998) pertaining to the
FD-psychology relationship. The fundamental tenets and predictions of the trait
theory are outlined.
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trait analysis. J Speech Lang Hear Res 2000, 43:749-768.
Personality superfactors and emotional adjustment are compared across a number
of voice disorders and a non-voice-disordered control in this well·controlled study.
The results are discussed within the context of the Trait theory of FD.
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The investigators compared personality factors in the identical groups as in the
previous article [34], but used a personality test that permitted a more precise
analysis of personality traits. The results revealed important differences in person­
ality traits between the FD and vocal nodules group, which were obscured at the
superfactor trait level of analysis.
36
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dysphonia: an evaluation using the Minnesota Multiphasic Personality Inven­
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laryngeal therapy for functional dysphonia: evidence of laryngeal lowering?
J Med Speech Lang Pathol 2001,9:169-175.
These investigators used acoustic theory and analysis to assess the "laryngeal
lowering hypothesis" to explain voice improvement in FD after successful manual
circumlaryngeal therapy. Results from formant frequency analysis provided indirect
support for Aronson's contention that the larynx lowers after circumlaryngeal mas­
sage.
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56
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