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about larynx anatomy, physiology,speech.pathology of laryngeal dystonia
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LARYNGEAL DYSTONIA
Dr.Roohia
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.
REQUIREMENTS FOR SPEECH PRODUCTION
Respiration
Phonation
Articulation
Resonance
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
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.
ExhalationAlso 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.
PHONATION
The act of phonation occurs in the larynx,
where the vocal cords are housed
The larynx is also called the “voice box”
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
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
ANATOMY: LARYNGEAL MUSCLES
ANATOMY: LARYNGEAL MUSCLES
ANATOMY: LARYNGEAL MOTION
Abduction of vocal ligament
ANATOMY: LARYNGEAL MOTION
Adduction of vocal ligament
ANATOMY: LARYNGEAL MOTION
Tension of vocal ligament
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
LARYNGEAL INNERVATION
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
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
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 speechPhonemes are either vowels or consonants
VOWELS
Vowel soundsThere 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
CONSONANTS
Consonants of English are classified by:
Place of articulation
Manner of articulation
Degree of Voicing
Consonant sounds make up 62% of our speech
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)
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)
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
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.
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
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
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
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.
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
The cerebellum is involved in the motor
control via the ventrolateral thalamus and
has a modulatory role in coordination of
voice and speech production
NEURAL PATHOLOGY NETWORK
. Direct projections from the laryngeal motor cortex (LM1) to the phonatorymotor nuclei(nucleus ambiguus, NA) descend via the corticobulbar/corticospinaltract (CBT/CST)
The putamen (Put) receives input from the LM1 and projects back to the LM1 via the globuspallidus&vth forming striato-pallido- thalamio cortical loop.
. Cerebellar motor input (Cbl) to the LM1 is via the VTh.
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.
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).
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”
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”
MIXED TYPE
Extremely rare, with symptoms of both
adductor and abductor type
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.
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
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
Koufman is based on independent visual
and acoustic evaluation using fiberoptic
laryngoscopy and extensive voice analysis.
Focal dystonias (LD) and
Nonfocal laryngeal dystonias
Blitzer and colleagues used a variation of the Koufman and Morrison and RammageClassification 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
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.
THANK YOU