Laryngeal dystonia, also known as spasmodic dysphonia, is a focal dystonia that affects the muscles of the larynx involved in speech production. It causes involuntary spasms of the vocal folds during speech, resulting in interruptions in phonation and changes to the voice quality. The spasms are usually task-specific, only occurring during voluntary speech and not other vocal behaviors like laughing or crying. There are different subtypes depending on whether the spasms cause hyperadduction or incomplete adduction of the vocal folds. Neurologically, it is thought to involve alterations in connectivity between the laryngeal motor cortex and brainstem nuclei responsible for phonation. Treatment involves voice therapy and in some

1. LARYNGEAL DYSTONIA
Dr.Roohia

2. DYSTONIA
Dystonias are a group of movement disorders
that are characterized by involuntary, action-
induced counterproductive muscle contraction.
Laryngeal dystonia(Spasmodic dysphonia (SD):
is a focal dystonia affecting the neural control of
the laryngeal musculature for speech production.
Spastic aphonia, spastic dysphonia, phonic
laryngeal spasm, coordinated laryngeal spasms,
mogiphonia, and laryngeal stuttering.

3. REQUIREMENTS FOR SPEECH PRODUCTION
Respiration
Phonation
Articulation
Resonance

4. WHAT IS REQUIRED FOR SOUND PRODUCTION?
Sound production requires two things:
Power/energy source
Vibrating element
When it comes to speech production, the
power source is air that comes from the
lungs and the vibration occurs in the vocal
cords

5. RESPIRATION
Also known as breathing
Two phases:
Inhalation
Also known as inspiration
Occurs when diaphragm lowers, which causes increased
volume/space in thoracic cavity. This results in negative pressure
in the lungs compared to the atmospheric pressure outside the
lungs; therefore, air rushes from outside the body into the oral
and nasal cavities, down the trachea, and into the lungs.
Exhalation
Also known as expiration
The decrease in the volume/space of thoracic cavity after
inhalation results in positive pressure in the lungs. If the airway
is open, air will rush out of the lungs (up the trachea and out the
oral and nasal cavities) in order to equalize the outside and
inside pressure.

6. PHONATION
The act of phonation occurs in the larynx,
where the vocal cords are housed
The larynx is also called the “voice box”

7. PHONATION
When air from the lungs is forced through closed vocal cords, the
vocal cords vibrate and phonation occurs
The pitch of sounds produced in the larynx is dependent upon the
tension of the vocal cords
Elongation and tension of the cords results in faster vibration =
higher frequency/pitch
Shortening and relaxation of the cords results in slower vibration =
lower frequency/pitch
Fundamental frequency of male voice=130 Hz
Fundamental frequency of female voice=220 Hz
The loudness of sounds produced in the larynx is dependent
upon the speed of air flowing through the glottis (space between
the cords).
The air speed is greatest when the pressure build-up below the vocal
cords (subglottal pressure) is high

8. ANATOMY: LARYNGEAL CARTILAGE
The Larynx is
composed of:
Cartilages (6)
Single cartilages:
Epiglottis, thyroid, cricoid
Paired cartilages:
Arytenoid, corniculate and
cuneiform
Muscles & Ligaments
Support and connect the
cartilages of the larynx
Form the vocal cords

9. ANATOMY: LARYNGEAL MUSCLES

10. ANATOMY: LARYNGEAL MUSCLES

11. ANATOMY: LARYNGEAL MOTION
Abduction of vocal ligament

12. ANATOMY: LARYNGEAL MOTION
Adduction of vocal ligament

13. ANATOMY: LARYNGEAL MOTION
Tension of vocal ligament

14. VOCAL CORDS
Also referred to as vocal
folds
Housed within the larynx
Attached anteriorly to the
thyroid cartilage and
posteriorly to the arytenoid
cartilages
Closed when we swallow to
protect our airway
Open when we are breathing
in order to allow air in/out of
lungs
Vibrate open and closed
during phonation

15. LARYNGEAL INNERVATION

17. THE PERIODS OF VOCAL FOLD CONTACT AND LACK OF
CONTACT IN ONE VIBRATORY CYCLE
Phase Description
Closing The vocal folds begin to close rapidly
from
their lower margin
Closed The medial edges of the vocal folds are
in
full contact
Opening The vocal folds begin to separate from
their
lower margin and gradually peel apart.
The superior margin remains in contact
until the end of this phase
Open The vocal folds are separated, the
longest
part of a normal vibratory cycle

19. VOCAL REGISTERS: CHARACTERISTICS OF VOCAL FOLD
ADDUCTION AND VIBRATION
Register may
include
Equivalent terms Vocal folds F0 range
Loft register
Highest vocal
frequancy
falsetto Thin,tense
lenghtened
Minimal vibration
275-1100
Modal register
Range of
fundamental
frequncies used in
speaking &singing
Chest,head,middle,
heavy voice
Complete
adduction
100-300
Pulse register
Lowest range of
vocal frequencies
laryngeal output is
percieved as
pulsatile
Vocal fry,glottal fry,
creaky voice
Long closed phase 20-60

20. ARTICULATION
Tongue
Lips
Teeth
Alveolar ridge (gums behind upper teeth)
Soft Palate
Hard Palate
Velum/uvula
The variable action of the tongue on all of the structures listed
above results in our ability to articulate different speech sounds
A PHONEME is the technical term for a specific sound of speech
Phonemes are either vowels or consonants

21. VOWELS
Vowel sounds
There are 5 vowels in the English language (a, e, i,
o, u), but there are 12 different vowels sounds (i.e.
the letter “i” makes different sounds in the words
“miss” and “mice”)
The articulation of the different vowel sounds
depends on:
The point of constriction
The degree of constriction
The degree of lip-rounding
The degree of muscle tension
Vowel sounds make up 38% of our speech

22. CONSONANTS
Consonants of English are classified by:
Place of articulation
Manner of articulation
Degree of Voicing
Consonant sounds make up 62% of our speech

23. CLASSIFICATION OF CONSONANTS BY PLACE OF
ARTICULATION
Bilabial: both lips come
together (p, b, m, w)
Labiodental: lower lip and
upper teeth make contact (f, v)
Dental: the tongue makes
contact with the upper teeth (-
th)
Alveolar: the tip of the tongue
makes contact with the alveolar
ridge (t, d, s, z, n, l)
Palatal: the tongue approaches
the palate (j, r, -sh)
Velar: back of the tongue
contacts the velum (k, g, -ng)
Glottal: this is really an
unvoiced vowel (h)

24. CLASSIFICATION OF CONSONANTS BY MANNER
OF ARTICULATION
Manner of articulation refers to the degree of
constriction as the consonants begin or end a syllable
Stops are defined by complete closure of the lips and
subsequent release (p, b)
Fricatives use an incomplete closure of the lips to create
turbulent noise (f, s, sh)
Nasals resonate through the nasal cavity (m, n)
Hint: try making these nasal sounds with your nostrils plugged 
Glides and Liquids are produced when the tongue
approaches a point of articulation within the mouth but
does not come close enough to obstruct or constrict the
flow of air enough to create turbulence (l, r, w)

25. VOICED VS. VOICELESS CONSONANTS
Voiced consonants are produced with the
vocal cords vibrating
Voiceless consonants are produced with the
vocal cords open
Example
The sounds /f/ and /v/ are both labiodental fricatives;
however, /f/ is voiceless and /v/ is voiced

26. RESONANCE
Dependent upon the size and shape of the:
Vocal Tract
Oral Cavity
Nasal Cavity
The resonant frequency of each of our voices
will differ depending on the size and shape of
the structures above, much like how the
resonance of a cello or bass differs from a
guitar, which differs from a ukelele.

27. LARYNGEAL DYSTONIA
Spasmodic dysphonia (SD)
spasmodic dysphonia, a form of movement disorder that
involves involuntary "spasms" of the muscles in the vocal
folds causing breaks of speech and affecting voice quality.
Focal, adult-onset dystonia of laryngeal muscles
Intermittent phonatory breaks during speech secondary to
spasms
Usually task specific - symptomatic when attempting voluntary
speech
May be asymptomatic during reflexive phonation (coughing,
laughing, crying, yawning)
Symptoms reduced/absent during singing or whisper

28. ASSOCIATIONS
May be associated with:
Other focal dystonias
Blepharospasms, Torticollis, Writer’s Cramp
Underlying neurological
Parkinson’s, ALS
Environmental
Infection, trauma, meds
Psychogenic stimulus
Stress

29. DEMOGRAPHICS
Affects approximately
1:10,000 Americans
Female to male ratio
3:1 up to 8:1
Peak age of onset 35-
45
Positive family history
in 12% of affected pt’s

30. NEUROPATHOLOGY
two different neurologic pathways involved in
voice production one being voluntary and
the other involuntary.
Corticobulbar fibers from the cerebral cortex
descend through the internal capsule and
synapse on the motor neurons in the nucleus
ambiguus.

31. alterations in anatomical connectivity of the
corticobulbar tract (CBT) descending from the
laryngeal/orofacial motor cortex to the brainstem
phonatory nuclei.
The link between dystonia and basal ganglia
dysfunction has been apparent Basal ganglia balance
excitation and inhibition of the thalamo-cortical circuit
involved in motor execution. This balance is thought
to be altered in task-specific dystonias due to
reduced GABAergic metabolism and dopaminergic
receptor binding leading to excessive motor cortical
excitation

32. The cerebellum is involved in the motor
control via the ventrolateral thalamus and
has a modulatory role in coordination of
voice and speech production

33. NEURAL PATHOLOGY NETWORK
. Direct projections from the
laryngeal motor cortex
(LM1) to the phonatory
motor nuclei(nucleus
ambiguus, NA) descend via
the
corticobulbar/corticospinal
tract (CBT/CST)
The putamen (Put)
receives input from the LM1
and projects back to the
LM1 via the globus
pallidus&vth forming striato-
pallido- thalamio cortical
loop.
. Cerebellar motor input
(Cbl) to the LM1 is via the

34. Microstructural
changes along the
CBT/CST as well as in
the regions directly or
indirectly contributing
to the CBT/CST found
in this study (dashed
areas) may affect
voluntary laryngeal
control in patients with
SD.

35. TYPES OF LARYNGEAL DYSTONIAS
Adductor – irregular hyperadduction of vocal
folds with excessive glottic closure
Abductor – incomplete, irregular vocal fold
approximation
Mixed – both elements are present
Adductor laryngeal breathing dystonia
(ALBD).

36. CLINICAL FEATURES: ADDUCTOR TYPE
Most common ~85% of diagnosed cases
Choked, strained-strangled voice, with abrupt
breaks in phonation in the middle of vowels
Breaks are due to hyper-adduction of the
folds
Difficulty with “We eat eels every day” and
“We mow our lawn all year”

37. CLINICAL FEATURES: ABDUCTOR TYPE
Rare ~15% of patients with SD
Breathy, effortful voice with abrupt breaks
resulting in whispered elements of their
speech.
Excessive and prolonged abduction during
voiceless consonants (/h/,/s/,/f/,/p/,/t/,/k/)
Difficulty with “The puppy bit the tape” and
“When he comes home we’ll feed him”

38. MIXED TYPE
Extremely rare, with symptoms of both
adductor and abductor type

39. ADDUCTOR LARYNGEAL
BREATHING DYSTONIA (ALBD).
persistent inspiratory stridor, usually normal
voice, and paroxysmal cough.
Some patients who have ALBD find it difficult
to breathe and swallow at the same time,
which results in dysphagia.

40. CLINICAL CLASSIFICATION
Ludlow and Connor based on constant
versus intermittent symptoms and the
presence or absence of tremor.
ADDUCTOR TYPE
(1) constant harsh and tight voice,
(2) intermittent pitch and voice breaks in the
middle of words,
(3) glottal stops with tremor at 4 Hz to 5 Hz
in the middle of words

41. ABDUCTOR TYPE
(1) constant whispering,
(2) intermittent breathiness with consonants
at the beginnings of words,
(3) voice tremor with breathy breaks at 4 Hz
to 5 Hz in the middle of words

42. Koufman is based on independent visual
and acoustic evaluation using fiberoptic
laryngoscopy and extensive voice analysis.
Focal dystonias (LD) and
Nonfocal laryngeal dystonias

43. Blitzer and colleagues used a variation of the
Koufman and Morrison and Rammage
Classification systems.
Type 1 hyperadduction is forceful
overcontraction at the glottic level only with tight
compression of the vocal processes and
arytenoids.
Type 2 is forceful contraction, including
contraction of the false cords.
In types 3 and 4, there is supraglottic narrowing
in the anteroposterior direction

44. Patients with intelligible speech and normal
stroboscopic findings are classified as mild.
Barely intelligible or unintelligible speech
and normal stroboscopy are considered
moderate
Unintelligible speech who are unable to
trigger the strobe are considered severe.

45. THANK YOU