Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Anatomy & physiology of voice Role of strobovideolaryngoscopy & laryngeal electromyogaphy in voice disorders • • • • • 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). • • • • 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 • • • • 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. 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 – • 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 – 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 • • • • • 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 • • • • rapid and early recruitment with a low voltage, full interference pattern duration is short, decreased amplitude. • • • • 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. • • • • • “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. • • • • • • 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 • • • • • 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 • 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.