Lecture 5 Voice Disorders Part 2: Neurologic Voice Disorders CD661OL (Aronson and Bless, 2009; Colton et al., 2011;2013; Sapienza & Hoffman-Ruddy 2014) 1. Neurologic Voice Disorders

Neurological Voice Disorders Three categories of phonatory dysfunction: Adduction / Abduction problems Stability problems Coordination problems (Ramig and Scherer, 1992) Vocal Fold Paralysis Vocal Fold Paresis SLN Paralysis Pseudobulbar palsy Adductor Spasmodic Dysphonia Huntington’s Corea Parkinson’s, ALS Essential Tremor Abductor Spasmodic Dysphonia 2. Aronson and Bless (2003) categorized neurological voice disorders by three types of phonatory dysfunction; adduction/abduction problems, stability problems and coordination problems. Adduction/abduction problems result from VF paralysis, paresis, SLN paralysis, Adductor SD, Huntiton’s Corea, and pseudobulbar palsy. Vocal stability problems result from diseases such as Parkinson’s, ALS and essential tremor. In a more recent publication they subdivided neurological voice disorders into 5 categories.

Neurological Voice Disorders Category 1 – Relatively constant voice disorders Category 2 – Arrhythmically Fluctuating Category 3 – Rhythmically Fluctuating Category 4 – Paroxysmal Category 5 – Loss of volitional phonation 3. Category 1 includes flaccid, spastic (pseudobulbar palsy), mixed flaccid-spastic and hypokinetic (parkinsonian) dysphonias. These disorders result in rather consistent and constant voice problems. Category 2 includes ataxic, choreic and dystonic dysphonias. These disorders result in fluctuating rather unpredictable voice qualities and behaviors. Category 3 includes tremor and myoclonus. These disorders result in vocal behaviors that are regularly, rhythmically fluctuating. Category 4 includes Tourette’s Syndrome Category 5 includes apraxia of phonation, akinetic mutism, foreign accent syndrome and frontal lobe syndrome. These disorders may result in aphonia and loss of volitional phonation.

Bilateral VF Paralysis Causes: (Benninger et al, 1998; Sataloff et al., 2007; Simpson et al., 2008) Iatrogenic (surgical trauma) - 44% Malignancies-17% Intubation -15%4 Progressive neurological disorders – 12% Other causes –bilateral cerebral damage damage to brainstem in area of CN X Diagnostics: Endoscopy 4. The most common cause of bilateral VF paralysis is surgical trauma (44%) followed by malignancies, intubation injury and neurological disease. Other causes include bilateral cerebral damage or bilateral brainstem damage. Diagnosis is via endoscopy.

Vocal Fold Bilateral Paralysis Paralysis in the adducted position causes * Strained/strangled, monotone, low pitched, low volume voice w/ possible hypernasality * Respiratory compromise due to decreased airway and stridor may be heard Paralysis in the abducted position causes * Aphonia. * Lack of airway protection for swallowing 5. According to Aronson and Bless(2009), site of lesion determines whether the VFs are paralyzed in the abducted or adducted position. Bilateral lesions of the RLN will result in bilateral paralysis of the PCA muscle and the VFs will be in the adducted position, while bilateral lesions to CN X above the origin of the pharyngeal, SLN and RLN branches will result in bilateral VF paralysis of the TA, LCA and IA muscles and the VFs will be in the abducted position. Voice quality and presence of aphonia will depend on VF position. Hypernasality may be observed if site of lesion is above the pharyngeal branch of CN X. When the site of lesion is above the branches of CN X and the VFs are paralyzed in the abducted position, airway protection is compromised and swallowing and respiratory safety are the primary concerns. When the lesion is below the branching in the RLN and the VFs are paralyzed in the adducted position, voice is functional but respiration is compromised.

Management of Bilateral VF Paralysis Abductor paralysis (PCA is paralyzed) & VFs in medial or paramedian position – 1. If airway is acceptable, wait and see if nerves spontaneously recover 2. Cordectomy, Arytenoidectomy or VF lateralization Adductor paralysis (TA, LCA & IA are paralyzed) & VFs in abducted position – 1. Tracheostomy for safe swallow 2. AC medial rotation 6. If the RLNs were injured during surgery but not severed and if the patient’s airway is not terribly obstructed, a ‘wait and see’ approach is recommended and major surgical interventions are deferred 6-9 months to see if the nerves will recover. If airway patency is an issue due to adducted VFs, tracheostomy may be needed. Surgeries which rotate the AC cartilage and result in VF lateralization can be used to create a better airway. Cordectomy and arytenoidectomy are also sometimes used to create a better airway and these involve removal of the AC, one VF or both. In cases of bilateral VF abduction due to paralysis of the VF adductors, a tracheostomy is needed for a safe swallow. Tracheal-esophageal puncture and a prosthesis with speaking valve will allow the patient to produce voice.

Unilateral VF Paralysis Causes: (Sataloff et al., 2007; Havas et al., 2002; Cavo, 2009) 50 % Iatrogenic (surgical injury) 36 % Idiopathic 24% Other : extralaryngeal tumor, intubation, viral Diagnostics: Videostroboscopy oral or nasal scope Laryngeal electromyography (EMG) MRI CN exam – CN X and XI Differentiate from AC dislocation or fixation Prognosis – may recover w/in 8-12 months 7. Unilateral VF paralysis is complete immobility or paralysis of one VF. The most common cause is injury to the RLN from surgery. The RLN provides innervation to the TA, LCA, IA and PCA muscles. Diagnostics include videostroboscopy. Electromyography, a technique which measures muscle activity, may be performed to confirm the paralysis. If the etiology of the paralysis is unknown, then an MRI may be ordered to rule out the presence of tumors or other structural changes that may be impinging on the nerve. When a nerve is injured during surgery, there is a possibility that it may recover and regenerate. Recovery time is 8 – 12 months.

Unilateral VF Paralysis Unilateral Vagus Nerve (CN X) lesions account for 90% of unilateral VF paralysis and cause flaccidity, decreased tone, & dysphagia Common cause is disease or trauma to RLN, w/ injury to left RLN more common than to right Other causes - unilateral brainstem strokes, unilateral trauma to RLN, or viral infections 8. Injury to the vagus nerve or it’s branch, the RLN, causes muscle flaccidity and hypotonicity. If VF closure is inadequate, then dysphagia may be a concern as well. The most common cause of VF paralysis is injury or disease to the RLN. Recall the circuitous route of the RLN and how on the R it loops under the subclavian artery and on the L it loops under the aorta before traveling up along side the trachea to inset in the laryngeal muscles. Thus, the left side is more susceptible to injury during heart or other thoracic surgeries.

Unilateral Vocal Fold Paralysis/Paresis Affected VF is usually in paramedian position Regarding vibration 1) VFs may have some anterior approximation 2) Healthy VF sometimes crosses midline to aid adduction 3) Airflow sets affected fold into vibration 4) Bernoulli Effect aids in VF closure Voice is hoarse, breathy, weak, sometimes strained Spontaneous Recovery: In cases of trauma to RLN, time frame is 8-9 months or up to a year. Corrective surgery not considered until after this time 9. Although the affected VF is paralyzed in the paramedian position, this does not mean that glottic closure will be complete, especially in the elderly. If the elderly patient also presents with ‘presbylaryngis’ (aging voice) and VF thinning and atrophy are apparent , then glottic closure will be more greatly affected. I have found that every unilateral VF paralysis patient is different. I’ve treated a professional singer with a paralyzed VF due to viral infection with very good glottic closure who, with voice therapy technique and revisiting basic foundational singing technique, was able to continue singing. He recovered completely 8 months later. Conversely, I saw a gentleman post- thyroidectomy with a unilateral VF paralysis due to surgical injury with very poor glottic closure. He had no spontaneous recovery and VF augmentation was the next course of treatment.

Unilateral VF Paralysis Management - Voice therapy ; VF augmentation Look for compensatory muscle tension secondary to paralysis * Intrinsic - A-P or medial-lateral compression, supraglottic sphinctering * Extrinsic – elevated larynx, neck tension 10. Early management of unilateral VF paralysis is often voice therapy or voice therapy and vocal fold augmentation via injection of hydroxelapetite or collagen. If the nerve has been injured, then there is a chance that it will recover function spontaneously. If we known from the surgical notes that the RLN was in fact severed, then paralysis is certain. Sometimes the surgeon will attempt to repair the nerve but this is typically unsuccessful. The only way to known for sure if the laryngeal muscles are paralyzed is to perform laryngeal electromyography. Electromyography is performed by an ENT and measures laryngeal muscle activity. It can help us determine if the4e is true muscle paralysis or not. Otherwise, it’s ’wait and see.’ I also want to mention that you need to assess for laryngeal muscle tension in paralysis patients. Many times these patients come to us with excessive laryngeal muscle tension in an attempt to compensate for incomplete glottic closure. If muscle tension is present, it must be treated first before laryngeal strengthening exercises are attempted.

11. Videostill of VF paralysis 11. Videostill of VF paralysis. R VF (your left) is paralyzed and fails to abduct on inhalation.

SLN Paralysis Causes: (Durson et al, 1996; Sataloff et al, 2007) Iatrogenic Viral infections Most common cause: thyroid surgery, can be unilateral or bilateral, BUT may also be due to virus. Results in paralysis of CT muscle Diagnostics: Videostroboscopy:(Sataloff, 2007; Tanaka et al, 1994) Ascending and descending pitch glides Look for rotation of posterior glottis to affected side Look for difference in vertical level of VFs 12. The SLN bilaterally innervates the cricothyroid muscles. Injury to SLN results in paralysis of the CT muscle. Depending on the study, the most common cause is surgery (Sataloff et al., 2007) or neuritis, which is inflammation of the SLN (Eckely et al., 1998). Recall that the CT muscle is our ‘pitch control’ muscle and that it also helps a little with VF adduction. Diagnosis includes videostroboscopy. Ascending pitch glides and high pitch phonation should be assessed during videostroboscopy and special attention should be paid to vertical level of the VFs. Rotation of the posterior glottis to the affected (paralyzed) side is often observed.

SLN Paralysis Effect on phonation: Perceptual: inability to raise pitch decreased pitch range decreased VF closure Perceptual: decreased habitual pitch breathiness decreased pitch and intensity ranges Treatment – Voice therapy; may spontaneously recover 13. Paralysis of the CT muscle results in a breathy voice with a lower habitual pitch, and decreased pitch and intensity ranges. Management involves voice therapy.

Vocal Fold Paresis Causes: (Heman-Ackah et al., 2006; Venketasubramanian et al., 1999) Neuropathy Goiter / Thyroiditis Idiopathic Viral Trauma Lyme’s Disease Stroke Diagnostics:(Sataloff et al., 2007; Koufman et al., 2000) Videostroboscopy Tasks Rapid repeated ‘ee’ Repeated ‘ee-hee- ‘pa, ta, ka’ Whistling Observe vocal processes Nodules, Cysts ??? Electromyography 14. Paresis means ‘weakness.’ VF paresis is under diagnosed and is often masked by laryngeal muscle tension. Diagnosis involves videostroboscopy with specific tasks that will cause laryngeal fatigue if paresis is present. Repeated ‘ee’, repeated ‘ee –hee,’ pitch glides, repetitions of ‘pə, tə, kə’ and whistling will often result in laryngeal fatigue if paresis is present. The weakness may present as incomplete adduction of the vocal processes and general decreases in overall adduction. Some researchers think that nodules and cysts occur due to compensation for laryngeal weakness, i.e. the individual increases medial compression in order to achieve adequate glottic closure (Koufman et al., 2000). Interesting thought. A unilateral cerebral stroke might also cause VF paresis. Recall that the CN nerves (which are lower motor neurons) receive bilateral innervation from the upper motor neurons that serve them. A unilateral stroke affecting the laryngeal area of the cerebrum causes both VFs to receive a little less innervation because both nuclei ambiguus (CN X motor nuclei) in the brainstem are receiving less innervation. I’ve seen several patients with mild VF paresis post stroke.

Vocal Fold Paresis Effects on phonation: Inadequate VF closure Perceptual: decreased intensity range and max intensity breathiness, hoarseness, unstable , inconsistent phonation Muscle tension secondary to paresis Vocal fatigue Treatment – Voice therapy and / or VF augmentation 15. The effects of inadequate or variable glottic closure results in breathiness, decreased intensity range, and in some cases, unstable or inconsistent phonation. There is a wide range of severity in VF paresis. But for some people, particularly those with high vocal demands, paresis may cause troublesome vocal fatigue and voice quality changes. For the professional voice user, even a mild VF paresis can cause problems during vocal performance.

Presbyphonia or Presbylaryngis Cause: Aging decreased innervation muscle atrophy = hypotonicity stiffer, thinner mucosa in males thicker, edematous mucosa in females ossification of cartilages loss of collagen & elastin fibers submucus glands atrophy (Colton et al.,2011) 16. Presbyphonia means ‘aging voice.’ The larynx changes with age and many of these changes directly affect VF vibration. As we age, all our muscles receive decreased innervation which leads to muscle atrophy and hypotonicity. Our laryngeal cartilages begin to calcify and become more bone-like. There is a loss of collagen and elastin fibers and the submucous glands of the VFs begin to atrophy as well. In males, the mucosa becomes thinner and stiffer. In females, the mucosa thickens and becomes edematous.

Presbyphonia Videostroboscopic signs: Vocal processes prominence Atrophy and VF thinning VF bowing Glottic gap Decreased amplitude of vibration Edema Yellowish discoloration 17. Videostroboscopic signs of presbyphonia include glottic gap or VF bowing, VF atrophy, and prominence of the vocal processes. In addition, the VFs may appear edematous and yellowish in color.

Presbyphonia Treatment – Voice Therapy Vocal Fold augmentation Effects on phonation: VF bowing Incomplete glottic closure Decreased amplitude Increased aperiodicity Male Fo increases Female Fo decreases Perceptual Breathy Hoarse Low pitch Tremor Patient complaints Vocal fatigue Trouble being heard Dislikes sound of voice Strain and effort 18. Patients may complain of vocal fatigue, vocal discomfort or pain if they are straining to project, improve vocal quality or produce voice. They may also show signs of hyperfunction (muscle tension) as a compensatory strategy. Due to incomplete closure and aperiodicity, the voice sounds breathy and hoarse. Treatment for presbyphonia involves voice therapy and / or VF augmentation via injection. Treatment – Voice Therapy Vocal Fold augmentation

19. Videostill of presbylaryngis 19. Videostill of presbylaryngis. Note bowing of VFs, prominence of vocal process tips and thinning VFs.

Spasmodic Dysphonia – Focal Dystonia Cause: CNS lesion – possibly basal ganglia and supplementary motor areas Diagnostics: Videostroboscopy Acoustic analysis Effects on phonation: Irregular, uncontrollable muscle movements disrupt VF vibration Must differentially dx from vocal tremor and MTD Three types: Adductor, Abductor, Mixed 20. SD is a ‘focal dystonia’ which is an abnormal movement in an isolated body part, in this case either the VF abductors, the adductors, or both. Recent research implies the cause of SD is likely a lesion in the CNS in the area of the basal ganglia or supplementary motor area. Diagnosis involves endoscopy and acoustic analysis. The result f SD is a muscle or group of muscles that contracts spontaneously, irregularly, and uncontrollably. Once thought to be a psychogenic disorder, there is often a psychogenic component due to the affect the disease has on patient’s communication and self image, and thus, work, social, and family life. SD must be differentially diagnosed from vocal tremor and MTD.

Three Types of SD Adductor – VF adductors (LCA, IA, TA) spasm periodically causing undesired hyperadduction. Result is harsh, strained, strangled sound with obvious effort. Most common. Abductor – VF abductor (PCA) spasms and abduct VF causing a breathy, hoarse, weak voice, decreased loudness is a problem. Mixed SD – combo of above two types Affects women more, age of onset between 30-50 years, reported occurring after URI, laryngeal trauma, vocal or emotional stress 21. There are three types of SD, adductor, abductor and mixed. Adductor SD is when the TA, LCA and IA muscles spasm uncontrollably and unexpectedly resulting in VF hyperadduction. Abductor SD is when the PCA muscles spasm uncontrollably and unexpectedly resulting in VF abduction during speech resulting in momentary aphonia and breathiness. SD is more common in women then men with onset between 30-50 years of age.

Spasmodic Dysphonia: Perceptual Adductor Strain – struggle Phonation breaks Pitch breaks Hoarseness & breathiness Harshness Vocal effort Abductor Breathiness Phonation breaks Difficulty transitioning from voiceless stops to vowels Pitch breaks Prolonged vowels 22. This slide shows typical perceptual qualities for adductor and abductor SD. Qualities that are underlined are hallmarks of the SD types.

Spasmodic Dysphonia Resource: National Spasmodic Dysphonia Association Treatment : Botox injections Voice therapy- adjunct Resource: National Spasmodic Dysphonia Association http://www.dysphonia.org/spasmodic-dysphonia.php 23. Treatment of SD involves Botox injections which are the ‘gold standard’ for SD treatment. However, we may see these patients for voice therapy to eliminate compensatory muscle tension and to maximize breath support.

Essential Tremor Cause: CNS lesion, likely extrapyramidal system Diagnostics: acoustic analysis videostroboscopy Tremor frequency 3 -7 Hz characterized by regular steady fluctuations in loudness and pitch Effects on phonation Phonatory instability & Tremor (Brin et al., 1992) 24. Essential tremor is a benign tremor and is likely due to a CNS lesion in the extrapyramidal system. Diagnosis is via acoustic analysis and endoscopy. Tremor frequency is typically 3-7 Hz and characterized by steady fluctuations in loudness and pitch. Tremor causes phonatory instability.

Essential Tremor of the Larynx Also called Organic or Familial Tremor Can be isolated to the voice, but may be associated w/ tremor in head, jaw, hands, tongue etc Always present in sustained phonation but can also be present in speech Tremor is quiet at rest but present during volitional movement. Onset is middle to late middle age; more common in women 25.Essential tremor is also termed familial or organic tremor. Although it can be isolated to the voice , other body areas may be involved such as the head, jaw or hands etc. The tremor will always be apparent during sustained phonation, which is an important assessment task, but may sometimes be less noticeable during speech. Essential tremor is an ‘intention’ tremor which means it occurs during movement (i.e. VF vibration).

Essential Tremor Tremor, frequency & intensity modulations Perceptual: (Aronson et al., 1968b) Tremor, frequency & intensity modulations Voice stoppages Strain – struggle Harshness, monopitch Treatment – Voice therapy – Barkmeier-Kramer approach Remediate muscle tension if present Breath support Pharmacological – Propranolol, Diazepam, Primidone, Clonazepam 26. Treatment is typically voice therapy to diminish the severity of the tremor, eliminate any compensatory muscle tension and improve breath support if necessary. Julie Barkmeier-Kramer , an SLP who is a voice specialist, has developed a therapy approach that we will talk more about during the voice therapy lectures. While there are medications that may reduce the tremor, most have undesirable side effects and are seldom used.

Differential Diagnosis SD or Vocal Tremor or Muscle Tension Dysphonia ??? Vocal tremor w/ muscle tension can sound like SD Severe muscle tension dysphonia can sound like SD How to differentially diagnose ? 27. Sometimes diagnosis of SD can be tricky. Vocal tremor with excessive laryngeal muscle tension due to compensation can sound like SD. Severe MTD can also sound like SD. So, how can we differentially diagnose SD from tremor and MTD?

Differential Diagnoses Step one – Perform laryngeal palpation Step two – Perform laryngeal massage and teach supraglottic relaxation exs. If dx is MTD, voice will improve significantly If dx is tremor, tension / strain-strangle quality will decrease and only tremor will be present If dx is SD, very little change will be observed. Also – MTD is consistent, SD is not (Colton et al, 2011) 28. In order to differentially diagnose SD from tremor and MTD, one must first eliminate any existing laryngeal muscle tension. First, palpate the larynx during speech and at rest and assess laryngeal height, width of thyrohyoid membrane and overall tension in extrinsic laryngeal musculature. Also assess floor of mouth tension. If tension is found, perform laryngeal massage and teach supraglottic and base of tongue relaxation exercises. This may take 15-20 minutes. If the true diagnosis is MTD, you will hear a marked improvement in vocal quality with no signs of SD symptoms. If the true diagnosis is vocal tremor, you will hear a vocal tremor, but without the strained, strangled quality of SD. If it’s truly SD, then the voice quality will change very little and the perceptual signs of SD will remain even in the absence of compensatory muscle tension.

Pseudobulbar Palsy Cause: Bilateral lesions in corticobulbar tract at level of internal capsule, midbrain or pons. Diagnostics – Neurologist Effects on phonation (Darley, 1969a;1969b;1975) Laryngeal muscle weakness and hyperactivity co-exist causing both hyperadduction and incomplete closure Treatment – Voice therapy w/ easy onset phonation, flow phonation, aspirated onsets, frontal tone focus, adequate breath support. 29. Pseudobulbar palsy results in a hyperkinetic spastic dysarthria where muscle weakness and spasticity co-exist. Thus, there is both hyperadduction and incomplete VF closure. Treatment involves voice therapy techniques such as easy onset, flow phonation and frontal tone focus.

Pseudobulbar Palsy Perceptual: Breathiness Strain / struggle Harshness Monopitch Monoloudness 30. Perceptual characteristics include both breathiness and a strain-struggle quality due to the hyperadduction and weakness.

Voice Problems in Neurological Diseases Amyotrophic Lateral Sclerosis – ALS Progressive disease of unknown cause Affects upper and lower motor neurons (cortex, brainstem, and spinal cord) Lack of innervation to muscles causes muscle wasting, muscle twitches, weakness, spasticity Articulation problems, dysphagia Voice: hoarseness, harshness, strain/struggle, hypernasal, breathy 31. In the voice clinic at Cedars Sinai and in our voice clinic here at CSUN, we don’t see too many patients with progressive neurological diseases such as ALS or Huntington’s Chorea. We do see Parkinson’s patients, however and some TBI and post stroke patients. In fact, Cedars has a dedicated ALS clinic for patients with ALS. Patients with ALS typically, or eventually, require AAC devices to communicate. Never the less, you should know how these disorders affect the voice.

Voice Problems in Neurological Diseases Lesions to Basal Ganglia or other parts of extrapyramidal system: Hyperkinesias: too much movement 1) Choreas – quick, jerky, purposeless movement; VOICE: irregular pitch/loudness, irregular respiration 2) Athetosis – hyperkinetic dystonia – slow, writhing movements VOICE: variable loudness, pitch, vocal quality 3) Huntington’s Chorea (specific type) inherited autosomal dominant degenerative disease affecting the basal ganglia. Onset = middle age. VOICE: Strained, strangled, harsh, monopitch voice, variable loudness/pitch, jerky irregular bursts of loud voice, sudden forced changes in breath. 32. Lesions to the basal ganglia can cause either hyper or hypokinesia. Hyperkinesia results in excessive unwanted movement. Movements can be either sudden and quick or slow and writhing. These conditions also affect the voice and can result in irregular pitch and loudness and irregular respiration.

Voice Problems in Neurological Diseases Lesions to Basal Ganglia or other parts of extrapyramidal system: Hypokinesia: too little movement Parkinson’s Disease - due to lack of dopamine in substansia nigra Slow rigid movements, decreased ROM, resting tremor, difficulty initiating movement Voice is breathy, weak, decreased loudness, monopitch, monoloudness, hoarse/harsh, sometimes tremor Vocal fold bowing or incomplete closure, w/ possible compensatory supraglottic squeezing, A-P compression, or FVF approximation 33. Parkinson’s disease is by far the most common progressive neurological disease seen and treated in voice clinics. It is a hypokinesia and results from damage to the substansia nigra which results in a lack of dopamine. Parkinson’s results in slow, rigid movements, decreased ROM, and resting tremor (tremor that occurs at rest but not during movement). The voice is typically breathy, weak, monotone and decreased in loudness. On endoscopy, the VFs may be bowed or incomplete glottic closure may be observed. Compensatory supraglottic squeezing or other intrinsic laryngeal muscle tension is not unusual. Voice problems relate to Parkinson’s disease are commonly treated via voice therapy with a therapy approach called Lee Silverman Voice Therapy which was specifically developed to treat Parkinson’s patients.

Voice Problems in Neurological Diseases Multiple Sclerosis – demyelinating progressive disease that attacks the myelin sheath causing breaks in transmitting axons in white matter in PNS and CNS. Damps or slows neuronal signal. Voice: impaired loudness control, harshness, hypernasality Decreased respiratory control, slow speech rate, impaired articulation 34. Multiple sclerosis can also affect the voice and respiration. MS is a demyelinating disease that causes breaks in the myelin sheath surrounding the nerve axons and thus slows the conduction of action potentials. MS voice issues may be helped by voice therapy that addresses maximizing breath support.

Voice Problems in Neurological Diseases Myasthenia Gravis – Autoimmune disease. Progressive failure to sustain maintained or repeated contraction of striated muscles. Due to blockage of acetylcholine at NMJ which results in muscle flaccidity. Onset for women 30’s, for men 60’s , occurs twice as often in women Voice: breathy, hypernasality, weak voice, decreased loudness, intermittent aphonia due to rapid fatigue Incomplete adduction/abduction of VFs w/ movement deteriorating with task repetition Pt. fatigues rapidly 35. Myasthenia Gravis (MG) is an autoimmune disease that results in a failure to sustain contraction of striated muscles and is caused by a lack of sufficient acteylcholine (ACH) at the neuromuscular junction. In patients with MG, the voice fatigues quickly and the individual moves from normal voice to aphonia very rapidly. However, given a few minutes to rest, during which the ACH builds up again, the voice will return but again fade quickly. This disorder is treated pharmacologically and not with voice therapy. However, sometimes we are first professional to encounter it, and if suspected, a referral to a neurologist is made.