Transcript Body-Cover Theory

Anatomy & physiology of voice
Role of strobovideolaryngoscopy & laryngeal
electromyogaphy in voice disorders
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Anatomy of the voice is not limited to the region
Practically all body systems affect the voice.
Larynx receives the greatest attention
sensitive & expressive component
larynx composed of four anatomic units:
Skeleton.
Mucosa.
 intrinsic muscles.
extrinsic muscles.
Laryngeal skeleton
 thyroid cartilage,
cricoid cartilage,
 two arytenoid cartilages
Thyroarytenoid,
extends on each side from the arytenoid
cartilage to the inside of thyroid
cartilage just below and behind the
thyroid prominence.
medial belly of the thyroarytenoid - vocalis
muscle,
(body of the vocal fold)
• Arytenoids - capable of complex
motion. arytenoids rock, glide, and
rotate.
• (Adduction) cartilages are brought
together in the midline & revolve
over the cricoid, moving inferiorly
and anteriorly.
• People use different strategies.
 vocal process ulcers
 laryngeal granulomas.
3.Apex of arytenoid cartilage
8.Base of arytenoid cartilage
13. Vocal process of arytenoid
cartilage
12.Arytenoid cartilaginous
neck
14. Articular surface arytenoid
cartilage
Larynx: mucosa
 lubricated epithelium
 superficial layer of the lamina propria,
 intermediate layer of lamina propria
VOCAL
LIGAMENT
 deep layer of the lamina propria
 Thyroarytenoid or vocalis muscle .
VOCAL FOLD NOT UNIFORM IN ITS ENTIRE LENGTH
Mass of collagen fibres –thyroid perichondrium –deep layer of L P .
ANTERIOR MACULA FLAVA:
ELASTIC FIBRES –
CONTINUES WITH INTERMEDIATE LAYER
POSTERIOR MACULA FLAVA :
• Allows the stiffness to change gradually from the pliable membranous
vocal fold to the stiffness of the thyroid cartilage
Blood vessels :
• vibratory margin come from posterior and anterior origins and run parallel to the
vibratory margin, with few vessels entering the mucosa perpendicularly or from
underlying muscle.
No glands
• presence would interfere with the smoothness of vibratory waves.
• Elastic and collagenous fibers of the lamina propria LIE IN PARALLEL
ARRANGEMENT .
FUNCTIONALLY, the five layers have different mechanical properties .
posterior two fifths -cartilaginous,
anterior three fifths -membranous
most of the vibratory function critical to sound quality occurs in the
membranous portion.
• MECHANICALLY- three layers
 cover (epithelium and Reinke space),
 transition (intermediate and deep layers of the lamina propria)
 body (the vocalis muscles).
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basement membrane
multilayered,
chemically complex structure.
• Type VII collagen loops that surround Type III collagen fibers in
the superficial layer of the lamina propria.
• IMPORTANCE OF FALSE CORDS :
• produce voice during certain abnormal circumstances,
• (dysphonia plica ventricularis.)
sophisticated turbulence patterns
downstream resistance
 vocal tract resonance.
PHYSICS OF AIRflOW THROUGH THE LARYNX ARE
COMPLEX
Intrinsic muscles
• cricothyroid,
• posterior and lateral cricoarytenoid,
transverse and oblique arytenoid,
aryepiglotticus,
• thyroarytenoid and its subsidiary
part, vocalis,
• thyroepiglotticus
ADDUCTS , LOWERS , SHORTENS ,
THICKENS -VOCAL FOLD .
LOWERS, STRETCHES, ELONGATES,
AND THINS - VOCAL FOLD,
INCREASE VOCAL
PITCH
ABDUCTS , ELEVATES , ELONGATES ,
THINS
• Intrinsic laryngeal muscles -skeletal muscles.
• Type I fibers :
 highly resistant to fatigue,
 contract slowly
 smaller in diameter.
• Type IIA fibers:
 principally oxidative metabolism
 high levels of oxidative enzymes and glycogen.
 contract rapidly
 fatigue resistant.
• Type IIB fibers:
 largest in diameter.
 contract quickly,
 fatigue easily.
• Extrinsic laryngeal musculature:
• maintains the position of the larynx in the neck
• Infrahyoid muscles:
thyrohyoid,
sternothyroid,
sternohyoid,
omohyoid.
• suprahyoid muscles:
digastric,
mylohyoid,
 geniohyoid, and
stylohyoid muscles.
• RESONATORS:
 supraglottic larynx,
tongue,
lips,
palate,
pharynx,
nasal cavity
 sinuses.
• lungs:
• power for voice production.
• TRAINED SINGER:
• not increased total lung capacity
decreasing his or her residual volume
 increasing respiratory efficiency
• abdominal musculature- support of the voice.
• diaphragm.
• function of the diaphragm muscle in singing is Complex & variable from singer
to singer
• purpose of abdominal support:
 maintain an efficient, constant power source
 inspiratory -expiratory mechanism.
TWO METHODS :
positioning the abdominal musculature under the rib cage
 distension of the abdomen.
Both can cause vocal problems if used incorrectly,
distending the abdomen (the inverse pressure approach) is especially dangerous,
• Musculoskeletal condition and position affect the vocal mechanism
• Stance deviation, such as from standing to supine, produces obvious changes in
respiratory function.
• Psychologic phenomena :
• Autonomic nervous system, which controls mucosal secretions and other
functions critical to voice production.
• fine muscle control.
Physiology of voice
• Voice:
• vocal folds (energy transducer) converts aerodynamic
power, generated by the chest, diaphragm, and
abdominal musculature, into acoustic power radiated at
the lips
• vocal folds
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airway protection,
respiration,
swallowing,
Phonation
Adequate breath support
Approximation of vocal folds
Favorable vibratory properties
Favorable vocal fold shape
Control of length and tension
• neuro-chronaxic theory
 (1950 Husson)
 vocal fold vibration to
an active pulsating
muscle contraction of the
vocal folds.
• Myoelastic-Aerodynamic
Theory
 1958, Van den Bergz
 2 basic principles
 1. fundamental frequency
of vocal fold vibration (the
rate at which vibration
recurs)
 mass
 viscoelasticity
of the vocal
folds
 subglottal
pressure.
 2. vocal folds are driven
into vibration by forces
(Bernoulli's principle.)
• Aerodynamic
• role of fluid dynamics
• air flows from a high-pressure region to a lowpressure region;
• Bernoulli's energy law:
• pressure of an incompressible flow decreases as the
particle velocity of the fluid increases, in accordance
with the principle of conservation of fluid energy
• continuity law of incompressible flow:
• particle velocity of an incompressible flow confined in
a duct increases as the cross-sectional area of the duct
decreases
• GLOTTAL CYCLE:
Phonation threshold pressure :
• minimal subglottal pressure required to drive the vocal folds
into vibration.
• Higher
• relatively dehydrated vocal folds
• vocal fold polyps
• Parkinson's disease
3 main closure forces.
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Bernoulli's effect of airflow
elasticity(mainly passive recoiling)
air escaping
drop in subglottal pressure) that decreases the driving force holding the vocal
fold tissues apart.
• 110 cy/sec(male)
• 200 cy/sec(female)
• Body-Cover Theory
• Mucosal Wave Movement
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• cover
• body
•epithelium
•superficial and intermediate
layers of the lamina propria
•pliable, elastic, and
nonmuscular (thus
noncontractile),
• deep layer of the lamina
propria
• thyroarytenoid muscle fibers
• more stiff , active contractile
properties
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alternating sequence of medial (closing)
and lateral (opening) movement of the
vocal folds spreading from lower to upper
lips along the medial surface of the vocal
fold mucosa.
mucosal wave decreases at higher
pitches and is not visible during
falsetto, suggesting that the motions of
the mucosa and the underlying tissue
become coupled.
• Linear versus Nonlinear Approach
• linear relationship between the system input and
output
• not be entirely linear.
• chaos theory approach
• multiple variables
• Expiratory Force
 conversational speech(passive expiration)
 Shouting & singing (active expiratory effort).
 functional dysphonia,
 insufficient prephonatory inspiration
 organic voice disorder & impaired pulmonary function,
 Not possible to compensate the glottic
defect
• Vocal Fold Positioning
 close enough ( airflow entrains oscillation).
 too wide:
 breathy, or aphonic,
 too tight:
• Vibratory Capacity of the Vocal Folds
• normal modal phonation
• mucosa undulates freely over the
underlying vocal ligament and vocalis
muscle
• histologic studies:
• Vocal Fold Shape
• falsetto mode, only the superior edges of the vocal
folds contact during the closing phase
• modal phonation( more efficient), the mucosal wave
begins on the inferior surface of the vocal fold.
• Pitch Control
• Changes in vocal fold length and tension
• fine motor control.
• size and physical properties ( larynx)
• range of pitch .
• child
» smaller larynx
» higher pitch range
• puberty
• age-related loss of elasticity and increasing ossification
of the thyroid lamina elevation of pitch.
• young men :
» low pitches
» vocal folds are longer and heavier
• Resonance
 raw sound
 prolongation, amplification, and filtering of sound by the
induction of sympathetic vibration.
 Formants:
 vocal frequencies that are enhanced by resonance
 pharynx itself does not resonate
 Actually its the air column
 Vocal training
 concentrates heavily on refining and maximizing
resonance.
 goal ( loudest and most pleasing sound possible with
minimal strain or pressure on the larynx.)
• Articulation
– source-filter hypothesis of speech
–larynx source of a constant sound
–consonants and vowels are formed by the
action of the lips, tongue, palate, and
pharynx.
• Sensory Input to Speech Control
–auditory feedback
–sensory input learning speech
– not essential for everyday use.
–Prelingually deaf
Laryngeal Electromyography
vocal fold paresis/paralysis,
differentiating laryngeal paralysis from
fixation.
Myasthenia gravis
diffuse polyneuropathies
ensure proper localization of botulinum
toxin injections.
supporting a diagnosis of conversion
reaction
Basic neurophysiology
• Resting membrane potential.
 interior of a muscle or nerve cell is
electrically negative with respect to its
exterior
In muscles & LMN -90 & 70 millivolts;
Application of an appropriate stimulus, nerves and
muscles generate action potentials.
 fast
propagated along the fiber without
decrement
• MOTOR UNIT :
• Single lower motor neuron and the muscle
fibers that it innervates.
• INNERVATION RATIO:
• Total number of muscle fibers in the muscle
Total number of motor axons .
• laryngeal muscles , approx 25:1
• Type 1 muscle
• sustained, lowintensity muscle
contractions;
• smaller motor
neurons
• activated at low
muscle tension
• first ones to be
observed in EMG
evaluation.
Type 2 fibers
• short bursts of high
intensity muscle
contractions
• large motor neurons
• recruited during
high muscle tension
 fairly expensive.
 Portable systems
 ABR units
 In addition to, not in place of.
• Electrodes:
• SURFACE :
skin or mucosa
noninvasive,
least selective electrode
not suitable for recording electrical
events ass. with individual motor
units
• needle electrodes:
• monopolar, bipolar, concentric, hooked
wire, and single-fiber
• percutaneous monopolar needle electrodes
routinely.
wider area of muscle
diameter is thinner
because no reference electrode
is built into the recording
needle.
Less tissue destruction and pain.
less expensive
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How to do
supine position,
neck extended
No anesthesia is used.
surface electrode - ground electrode,
Reference (also surface) - cheek.
• cricothyroid:
 cricothyroid (CT) notch ( CT space) :
 inserting the needle approximately 0.5 cm from the midline
and angled laterally 30 to 45
 first passes through the sternohyoid muscle.
 CT muscle ( approx.1 cm deep).
 position of the electrode confirmed by asking the patient to
phonate /i/ at a low pitch and then asked to raise the pitch. If
the electrode is in a normal CT muscle, the EMG activity
increases sharply.
• THYROARYTENOID(ta) MUSCLE.
0.5 cm from the midline of the CT notch and is
angled superiorly and laterally 30 to 45
 1 to 2 cm beneath the skin
Confimed by asking the patient to say and sustain
the vowel sound /i/.
 a sharp and sustained increase in EMG activity.
(Faulty ) lateral cricoarytenoid muscle there is an
increase and rapid drop-off in EMG activity.
POSTERIOR CRICOARYTENOID MUSCLE.
Passing a needle through the cricothyroid
membrane, airway, and cricoid cartilage
posteriorly.
 sniffing, swallowing and phonating the sound /i/.
Analysis
 during insertion
 at rest
 during minimal voluntary contraction
 during maximal voluntary contraction.
• Insertional activity:
• no more than several hundred milliseconds
• Prolonged-early nerve and muscle injuries,
• Decreased-late nerve and muscle injuries,
» replacement of normal muscle with scar
tissue or fat
• Spontaneous activity:
no spontaneous electrical activity at rest.
severely denervated muscle with unstable
electrical charges.
process that caused the injury is ongoing.
usually begins 2 to 3 weeks
poor prognosis
• Waveform morphology
• Shape:
• biphasic;
• upward positive spike and a downward negative
spike
• amplitude:
• 200 to 500 microvolts
• duration :
• 5 to 6 milliseconds
• early phases of regeneration,
• small amplitudes, long durations, and polyphasic
shapes
• nascent units ( recent nerve injury).
regeneration progresses,
Greater amplitudes than normal (because of
the greater number of muscle fibers in the
motor unit),
 polyphasic (because of changes in the muscle
membrane potentials),
 prolonged duration (because of changes in the
myelin sheath and nerve conduction velocity).
polyphasic or as giant polyphasic potentials;
 implies old nerve injury.
Recruitment :
serial activation of motor units during increased voluntary
muscle contraction
LEMG :
increase in the number and density of motor unit
potentials
reflects the degree of innervation,
number of active nerve fibers within a given muscle.
• Fibrillation potentials :
• spontaneous,
• single-fiber muscle
action potentials
• amplitude of several
hundred microvolts
• < 2 milliseconds,
• 1 to 50 Hz.
• biphasic or triphasic
appearance with an
initial positive
deflection.
• denervation and
axonal loss.
• Complex repetitive
discharges
group of muscle fibers
discharges repetitively in
near synchrony
 abrupt onset and
cessation
5 and 100 Hz,
indicates chronicity
neuropathic and
myopathic processes.
• Myotonic potentials
 repetitive discharges at
rates of 20 to 150 Hz
 amplitudes of 20 mV to
1 mV,
 fibrillation potentials or
positive sharp waves.
 wax and wane
 indicate muscle
membrane instability
disorders of
clinicalmyotonia, such
as myotonic dystrophy.
• In complete paralysis
• Myopathy
• initially electrical silence;
• positive sharp waves or fibrillation potentials (denervation )
• polyphasic, high-amplitude, and long-duration responsesReinnervation
• loss of motor units following paralysis, which results in
decreased recruitment
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rapid and early recruitment with a low voltage,
full interference pattern
duration is short,
decreased amplitude.
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insertional activity,amplitude,duration - normal.
no excessive polyphasic motor units.
Recruitment is decreased.
firing rate of the motor unit is slow.
• Upper motor neuropathy
Laryngeal myasthenia
• insertional activity - normal.
• spontaneous activity-nil
• With minimal muscle contraction
• MUAP variation in amplitude and duration
• (reflecting intermittent failure of conduction across
the neuromuscular junction).
• recruitment & interference patterns - normal.
• Repetitive nerve stimulation -abnormal (lack of
increased recruitment with each repetitive
stimulation.)
• may be the first and only sign of systemic myasthenia
gravis
• Laryngeal dystonia (spasmodic dysphonia)
• intermittent sudden increases in muscle activity
coinciding with momentary voice rest
• Vocal fold immobility:
• laryngeal joint injuries ( intubation trauma)
• Delayed management -joint ankylosis.
• LEMG findings are normal
• cricoarytenoid joint arthritis,
• blunt neck trauma,
• injury to the recurrent laryngeal nerve.
• vagus nerve /brain stem lesion.
• involvement of both the thyroarytenoid (adductor muscles) &
cricothyroid muscles
• If cricothyroid muscle / thyroarytenoid alone superior
laryngeal nerve lesion/ recurrent laryngeal nerve injury.
VOCAL CORD PARALYSIS
EMG FINDINGS
>21
DAYS
MILD
6MONT
HS
MODERATE
>21 DAYS
6 MON
SEVERE
>21 DAYS
6 MON
MOTOR UNIT
RECRUITMENT
↓/↓↓
NL
↓↓/NF
↓/↓↓
NF
NF
MOTOR UNIT
CONFIGURATIO
N
NL
NL
NL
NL/POLY
0
0
FIBRILLATIONS
0
0
+
+
++/+++
CRD/++
PROGNOSIS
EXCELLE
NT
EXCELLE
NT
FAVORABLE
FAVORABLE
POOR
POOR
SURGERY
-
-
NO
PERMANENT
SX
CONSIDER
SPEECH
THERPY
PERFORM
SX BY 6
MONTHS
Stroboscopy
BRIEF HISTORY:
Bozzini: Indirect laryngoscopy
1806 - angled speculum with a mirror insert
1854 Manuel Garcia, a Spanish-born voice
teacher first visualized his larynx with a
small dental mirror using sunlight as a light
source.
• 1895, Oertel - first laryngostroboscope.
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• “An instrument for determining the speed of the
cyclic motion that cause the motion to appear
slowed /stopped’’
• illusion of slow motion.
• Talbot law:
• no more than five distinct images/sec.
• 0.2 sec.
• makes the vocal fold vibrations appear to slow
down
still images are recorded at selected points from sequential
vibratory cycles and the human eye automatically fills in the
missing pieces by fusing the images into what it sees as motion.
• persistence of vision.
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Strobovideolaryngoscopy
stroboscopic light source,
endoscope,
microphone,
video camera,
recording device,
video monitor.
• strobe light create two effects
• running phase (often called strobe)
• stop or locked phase
Synchronization: at the same frequency as phonation(
perceptual stopped image or standstill)
asynchronization: slight variation of the frequency
most comfortable pitch and loudness (MCPL)
protocol
Sustained “ee” at patient's most comfortable pitch
and loudness (MCPL) (several)
“ee” on inhalation
Glide midrange to high, sustaining the high note
Glide midrange to low, sustaining the low note
Quiet “ee”
Loud “ee”
Sustained “ee” at MCPL using locked mode
Trial therapy or laryngeal manipulation
Used in vocal fold vibration patterns,
mucosal pliability,
 layered structure of the vocal folds,
 undersurface of the vocal fold edge
 assessing stiffness, scar, or submucosal injury;
detecting small vocal fold lesions;
 estimating the depth of invasion of a tumor;
 identifying asymmetric mass or tension;
 determining the resumption of phonation after
phonosurgery.
• Stroboscopic parameters
• closure pattern,
• phase closure,
• amplitude of vibration,
• mucosal wave,
• adynamic segments,
• vertical closure level,
• symmetry,
• regularity.
• closure and mucosal wave are often considered key
indicators
• subject to reliability and validity errors
• Closure pattern .
• Is the glottis completely closed / not closed?
• Patterns of incomplete closure
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posterior gap
anterior gap
spindle-shaped gap
hourglass-shaped gap
irregular, and variable.
• complete closure is the most common pattern
for men and it occurs in some women at
MCPL or with increased loudness
• Mucosal wave
• vertical upheaval of the cover over the body.
• infraglottic lip of the vocal fold, then travels up the medial
edge and across the superior surface of the fold.
• Normally, half the width of the vocal fold during phonation
at MCPL.
Increased mucosal wave
polypoid degeneration
increased subglottal air pressure
decreased or even absent ( stiff ).
normally
increasing pitch, aging.
pathologic conditions,
scarring, sulcus vocalis.
• Nodules:
 symmetric
 reduced amplitude of vibration,
 maintenance of periodicity,
 intact mucosal waves,
 hourglass closure.
• Vocal fold polyps:
unilateral,
have asymmetric vibration
 variable periodicity
 Mucosal wave can be absent(mass effect with large polyps)
Glottic closure asymmetric.
• Cysts :
• within the vocal fold lamina propria
• Mucosal wave is frequently absent and aperiodic if present
• abnormal findings in up to 58% of healthy, asymptomatic
professional singers
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valuable complement(vocal history & physical examination)
• not a test to be done in the absence of other clinical data.
• Limitation:
composite recording made from several glottal cycles
Common voice problems :
• laryngopharyngeal reflux,
• muscle tension dysphonia,
• vocal fold lesions (eg, nodules and polyps),
• cysts,
• vocal fold scarring,
• changes in vocal fold mobility.
• Laryngopharyngeal reflux :
• retrograde movement of gastric contents
• dysphonia, globus pharyngeus, mild dysphagia,
chronic cough, excessive throat mucus, nonproductive
chronic throat clearing
• most have silent reflux,
• only 35% of patients
• directly and indirectly theory(vagally mediated
response ).
• History
• 24-hour dual-sensor pH/impedance probes
• diet changes, lifestyle/behavior modifications, medical
intervention, occasionally, surgery.
• Benign vocal fold masses:
nodules, polyps, and cysts
• Dysphonia is the most common
presenting symptom
• Nodules: subepithelial scar
deposition,
• Hoarseness
• presence is not always
compromising
• midmusculomembranous
region (junction of the anterior
• one third and posterior two
thirds of the entire vocal fold)
• Management
• Medical, Behavioral, Surgical
(minimum of 3 months)
• Vocal fold polyps,
• subepithelial fibrosis and
deposition,
• are histologically similar
• unilateral.
• hoarseness, vocal fatigue
• Vocal fold cysts :
• hoarseness,
• superficial lamina propria
• epidermoid (squamous inclusion) cysts
»phonotrauma,
» congenital.
• mucus retention cysts:
»occlusion of mucus glands
»inferior surface of the vocal fold.
• Vocal fold scarring
• Greek eschara (scab)
– inflammatory,
– neoplastic,
– traumatic,
– iatrogenic
• inflammatory and iatrogenic(m.c)
• depend on the location of vocal fold scar
• Sulcus vocalis
• linear invagination of epithelium
along the medial edgeof the vocal fold
into or beyond the superficial layer of the
lamina propria
• Types I and II
• longitudinal depressions in the epithelium
• vocal process to anterior commissure),
• differ only in depth of penetration.
• Type I
• type II
• Extends to or beyond the vocal ligament,
• loss of superficial lamina propria.
• Type III
• deep, focal indentation of epithelium
varix
• Prominent or enlarged vessels
within the vocal folds superficial
lamina Propria
• superior surface of the vocal fold
• Reason not known
– diet changes, behavior modification,
and PPIs, is imperative.
– Maintaining adequate hydration
– Indication for surgery
– varices is recurrent vocal fold
hemorrhage pulseddye
– laser (PDL) and KTP lasers
Normal stroboscopy
1.
2.