Laryngology Seminar
Spasmodic Dysphonia vs. Muscle Tension Dysphonia:
a Clinical Approach for Differential Diagnosis
R3 郭士偉 2005/12/29
INTRODUCTION
 Spasmodic dysphonia (SD) is a neuromotor disturbance in the class of focal
dystonias (types: Adductor, Abductor, mixed)
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Muscle tension dysphonia (MTD) is a functional voice problem related to muscle
misuse (i.e., excess or dysregulated laryngeal muscle tension)
Both conditions produce disordered laryngeal movements affecting voice
production
Differential diagnosis of SD continues to be based upon auditory-perceptual
assessment (and voice therapy failure)- inherently problematic
MTD can mimic the perceptual attributes of the SDs
potential for miscalssification & inappropriate (needless, wasteful) behavioral,
medical or surgical interventions
Reconginzing the difference among (1) the subtypes of SD, and (2) MTD- can
reduce diagnostic confusion and improve management outcomes
THE SPASMODIC DYSPHONIAS
 neurogenic- adult onset, action-induced, task-specific, focal dystonia
 adductor SD (ADSD)- voice breaks in vowels
 intermittent voice offsets (voice breaks) in the middle of vowels (i.e., voice
stoppages)
 spasmodic hyperadduction of the true vocal folds that interrupts phonation
(i.e., quick glottic overclosures)
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 strained-strangled, effortful voice quality
abductor SD (ABSD)- prolonged voiceless consonants
 rare form (10% of laryngeal dystonia)
 abduction of vocal folds (devoicing gesture)
 prolonged voiceless consonants (long VOT): difficulty with voice onset
following voiceless sounds e.g. /h, s, f, p, t, k/. especially noticeable when
attempting to turn voice on after 'h' as in happy
 breathy voice quality, ? normal vowels (except in very severe cases)
FEATURES of ADSD: TASK SPECIFICITY & DIAGNOSTIC PROBES
 task specificity= variable performance on the basis task demands, a feature of
dysphonia
 Rainbow Passage (mix of voiced & voiceless contexts)
 sustained vowel (reduction/resolution of symptoms), esp. if produced at slightly
higher pitch than habitual
 sustained vowel is often less severe as compared with RB passage (53% of
ADSD patients)... May have some difficulty initiating vowel at habitual pitch
(abrupt onset, but improved in middle of vowel)
TASK SPECIFICITY in ADSD
 sentences loaded with voiced segments (& lots of vowels) will provoke (worsen)
symptoms (i.e., more strain, voice breaks)
 early one morning a man and a woman were ambling along a one-nile lane
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running near Rainly Island Avenue
 Albert eats eggs every Easter early in the a.m.
 we mow our lawn all year
 we rode along Rhode Island Avenue
sentences loaded with voiceless segments will decrease symptoms (i.e.,
improved performance...less strain, voice breaks)
 he saw half a shape mystically cross fifty or sixty steps in front of his sister
Kathy's house
 when he comes home we'll feed him
 Harry had a whole half pound hamburger
 she sells seashells by the seashore
 the puppy pawed the tape
compare repeated productions of /wi/ v.s /pi/, /ti/, /ki/. ADSD worse on /wi/ (i.e.,
more strain, effort, voice breaks). Improvement on syllable repeats with
voiceless consonants
compare rapid “ah, ah, ah” v.s “hah, hah, hah”- ADSD improved on “hah”
counting “ eighty series” (difficult) compared to “sixty series”
pitch-glide: low to high (asymptomatic in highest pitches)
Falsetto (counting to ten): asymptomatic/improved compared to normal speech
singing happy birthday: asymptomatic esp. when singing in highest pitch
whisper: asymptomatic
“islands of normal speech” (few words)… free of strained-strangled
quality…short-lived, transient…esp. after spontaneous laugh
ADSD: OTHER SYMPTOMS/SIGNS
 palpation of laryngeal region reveals negligible signs of excess laryngeal
musculoskeletal tension (pure SD)
 minimal pain, tenderness, hypertonicity
 no sustained response to manual circumlaryngeal techniques
ABSD: TASK SPECIFICITY
 diagnostic tasks…performance on sentence and syllable stimuli is opposite to
ADSD
 sentences with voiceless-voiced segments (mostly voice less consonants)
provokes more symptoms (i.e., elicits abductor spasms…difficulty in turning
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voice on following voiceless cons.)
sentences with all voiced segments…improved performance
/pi/, /ti/, and /ki/ worse than /wi/
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‘hah, hah, hah’ worse than ‘ah, ah, ah’
sixty-series more difficult than eighty series
sustained vowels, falsetto, singing, laughing are easier than connected speech
no pain
MUSCLE TENSION DYSPHONIA
 what precisely constitutes MTD is unclear
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narrow vs. broad conceptualization
recurrent feature in all descriptions is laryngeal and extralaryngeal hyperfunction
multiple sources of dysregulated muscle activity
psychological and/or personality factors that tend to induce tension
technical misuses of the vocal mechanism
learned adaptation following URI
compensation for underlying vocal fold pathology
increased laryngeal tone secondary to LPR
CARDINCAL FEATURES in MTD
 vocal fatigue
 pitch and loudness locked
 paralaryngeal hypertonicity (hyo-laryngeal sling is stiff/immobile)
 tight M-L glottic and/or supraglottic contraction, A-P glottic an/or supraglottic
contraction, IGC, posterior glottic chink, and bowing
 circumlaryngeal palpation reveals elevation, tenderness and pain, muscle
tautness, “larynx held”
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perceptual features can mimic various subtypes of SD
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patients respond quickly to manual treatment techniques (i.e., circumlaryngeal
massage and/or reposturing approaches)
CIRCUMLARYNGEAL TECHNIQUE
A. Medial suprahyoid musculature is palpated
at rest and during upward pitch glide
maneuvers. Focal sites of tenderness and taut
bands signal excessive muscle activity
B. Signs of excess laryngeal tension are
assayed by 1) evaluating presence of focal sites
of pain or nodularity, 2) determining size of
thyrohyoid space, and 3) observing voice
effect of downward traction over superior
border of thyroid lamina and during
circumlaryngeal massage
C. Larynx is compressed by exerting
anterior-to-posterior pressure over inferior
border of hyoid bone
D. Manual tension reduction procedure
(circurmlaryngeal massage) with hand
configuration and placement. Pressure is
applied in circular motion over tips of hyoid
bone and within thyrohyoid space. Procedure
is repeated over posterior borders of thyroid
cartilage and larynx is gently pulled
downward.
ADSD vs. MTD: IS TASK-SPECIFICITY A DISTINGUISHING FEATURE?
 Methods: voice stimuli (order randomized within & across)
 early one morning a man and a woman were ambling along a one-mile lane
running near Rainy Island Avenue
 He saw half a shape mystically cross fifty or sixty steps in front of his sister
Kathy’s house
 Five graduate SLP students rated dysphonia severity
 10 cm visual analog scale
 Results:
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Sensitivity: proportion of correctly identified cases (ADSD subjects)
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Specificity: proportion of correctly identified non-cases (MTD subjects)
Reiceiver operating characteristic (ROC) curve generated using the variable
cutoff criterion to determine a case.
E.g., 1 cm cutoff required voiceless sentence to be rated at least 1 cm less
severe than rating for voiced sentence
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Figure
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ADSD is “fairly” task-specific (1> cm) (48% sensitivity)
MTD is not task-specific (88% to 100% specificity, as size of difference
increases 1 cm to 4 cm)
Clinical implications:
 if don’t observe task-specificity, can’t rule out ADSD (look for other
confirmatory signs/symptoms, i.e., SV vs. connected speech, singing,
islands of normal speech, falsetto).
 But, if observe task-specificity (1) likely ADSD, (2) cant rule out MTD,
especially as size of difference increases
 clinicians must survey/employ specific voice stimuli during diagnostic
session, otherwise miss important distinguishing features (i.e.,
task-specificity)
DISTINGUISHING SD and MTD, in MTD……
 little evidence of task specificity in MTD
 MTD’s sustained vowel commensurate with connected speech
 no obvious difference between voiced and voiceless contexts (all contexts
difficult)
 MTD continuous, rarely intermittent (no islands of normal speech)
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no improvement with falsetto or singing
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positive findings upon palpation….exquisitely sensitive…pain, jump sign, wince,
withdraw
no tremor
sustained improvement following circumlaryngeal therapy
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CONCLUSION
 important for clinician to appreciate the effects of laryngeal and paralaryngeal
tension on voice
 distinguish among disorders characterized by abnormal muscular tension
(dystonic and non-dystonic)
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ensure proper diagnosis and selection of appropriate treatment for both MTD and
SD
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