Neurological Disorders Affecting Voice

(Neurological Disorders) Peripheral Nervous System Pathology:

• Paresis or paralysis of the superior or recurrent laryngeal nerve

  • Most common is recurrent laryngeal nerve

  • Less common is superior laryngeal nerve involvement

• Closer injury to brainstem may affect both superior & recurrent laryngeal nerve; more distal injury typically results in injury to 1 nerve

• Causes: surgical trauma, cardiovascular disease, neurologic diseases, accidental trauma

• Idiopathic: 30-35% of cases

Neurological Disorders Affecting Voice:

• Directly caused by an interruption of the innervation to the larynx

• Central & Peripheral Insults

• Voice & laryngeal manifestations

  • Unilateral vocal fold paralysis

• Progressive neurologic disease

  • Deterioration of many central & peripheral motor control systems

  • Respiration, resonance, swallowing

(Neurological Disorders Affecting Voice) Peripheral Nervous System Pathology:

• Recurrent Laryngeal Nerve (RLN) Paralysis: Unilateral

  • Laryngeal Findings

  • Phonatory Effects

• Recurrent Laryngeal Nerve (RLN) Paralysis: Bilateral

  • Laryngeal Findings

  • Phonatory Effects

(Neurological Disorders Affecting Voice - PNS Pathology) Superior Laryngeal Nerve Paralysis (External Branch):

• Unilateral ESLN paralysis = Unilateral Cricothyroid m. dysfunction

(Neurological Disorders Affecting Voice - PNS Pathology) Laryngeal Findings:

• Epiglottic petiole deviation to the side of weakness during high pitched voice as a possible diagnostic marker

(Neurological Disorders Affecting Voice - PNS Pathology) Phonatory Effects:

• Mild dysphonia, loss of upper pitch range, voice characterized by weakness, increased physical effort expended to produce voice

What is Unilateral VF Paralysis?

• Mild to severe dysphonia

  • Dependent on the resting position of the paralyzed fold

• Breathiness, low intensity, diplophonia

(Neurological Disorders Affecting Voice - PNS Pathology) How do you treat Unilateral VF Paralysis?

• Voice therapy

• Phonosurgical management

  • Injection medialization laryngoplasty

  • Medialization thyroplasty (inserting material into VF so it bulks it up for better vibration)

  • Laryngeal reinnervation

What is Injection Medialization Laryngoplasty?

• Injection of resorbable material

  • Gelform paste

  • Collagen

  • Fat

  • Alloderm

• Bioimplants

What are Movement Disorders of the Larynx?

• Spasmodic Dysphonia (SD)

  • ADductor Spasmodic Dysphonia (ADSD)

  • ABductor Spasmodic Dysphonia (ABSD)

  • Mixed SD

• +/ - Essential Voice Tremor

What is Spasmodic Dysphonia (SD)?

• Neurologic voice disorder wherein involuntary vocal fold spasms occur in the intrinsic laryngeal muscles

What is ADductor Spasmodic Dysphonia (ADSD)?

• Strained-strangled voice w/ voice stoppages/spasms

What is ABductor Spasmodic Dysphonia (ABSD)?

• Involuntary breathy bursts/ spasms

What is Mixed Spasmodic Dysphonia?

• Both strained voice stoppages & breathy bursts

Is Essential Tremor a type of SD?

• NO! Essential tremor is NOT a type of SD

  • Can occur concomitantly

  • Stimulability Testing: Sustain long /i/

  • Listen for the consistent quiver or shakiness to the voice throughout ALL SOUNDS (i.e., not sound specific)

Spasmodic Dysphonia:

• Symptoms often worsen initially & then plateau over 1-2 years

• Symptom Onset:

  • 24% sudden onset

  • 76% gradual onset

• 3rd most prevalent form of focal dystonia

• Cause is still unknown

• Precipitating Factors:

  • URI: 33%

  • During or after pregnancy: 10%

  • Intubation: 6%

  • Stressful Event: 42%

What are some considerations for Spasmodic Dysphonia?

• Often misdiagnosed

  • Historically thought of as a psychogenic disorder

• Can be confused w/ muscle tension dysphonia (MTD)

• Laryngoscopy often looks “normal”

• Listening is key component

What should you listen in on for SD?

• Sound-specific voice breaks or ‘spasms’ affecting voice quality

  • Halted, strained, strangled, breathy, jerky, squeezed, hoarse, “catches/stops”

• Perceptually, the type of voice break we hear depends on which muscle is affected

Does the voice ever sound “normal?”

• Laughing

• Talking in high pitch (falsetto)

• Emotional speech or when crying

• Singing (sometimes)

• Screaming (if able)

• Yawning

• Whisper

• Loud (sometimes)

• Accents

• Alchohol

  • Sometimes symptoms are worse after consumption

What is the most common type of SD?

• Adductor Spasmodic Dysphonia!

• Action-Induced: VFs close for prolonged periods of time during voiced sounds

What is the primary muscle affected in Adductor Spasmodic Dysphonia?

• Thyroarytenoid (TA)

  • Sometimes also LCA

  • Task & sound specific:

    • all vowels + b, d, g, j, m, n, l, r, z

    • For voiced sounds, the vocal folds are brought together and air pressure from the lungs causes them to vibrate as air passes through

What is the rarer type of SD?

• ABductor Spasmodic Dysphonia!

• Action-induced: VFs open for prolonged periods of time during voiceless speech sounds

What is the primary muscle affected in ABductor Spasmodic Dysphonia?

• Posterior cricoarytenoid

  • Task & sound specific: p, t, k, f, s, sh, h

  • for voiceless sounds, the vocal folds are pulled apart, allowing air to flow freely without causing vibration. 

Additional Variants?

• Mixed: AB + AD = Least common type!

• Vocal/Essential Tremor

  • Not a type of SD

  • Can co-occur w/ SD

(Stimuli Sentences) ADSD:

• Go get a bigger egg

• We mow our lawn all year

• Adam eats apple & oranges

• Count from 80-90

(Stimuli Sentences) ABSD:

• Harry hit the hammer hard

• Fat Freddie sells French fries

• Pet the pound puppy

• Count from 60-70

(Stimuli Sentences) What stimuli will patients with Mixed SD exhibit spasms on?

• Patients will exhibit spasms on both sets of stimuli

What does Stimulability Testing involve?

• Stimulability testing for differential diagnosis w/ MTD

  • Whisper 1-10

  • High pitch (falsetto) count 1-10

  • Sing Happy Birthday

What is the current gold standard for treating SD?

• BOTOX is gold standard

• Temporary effects

• Neurotoxin → Block nerve impulses sent from the brain to the receptor sites in the muscles

• Dose amounts are adjustable to individualize for each patient

• Requires repeat injections ~ 3 months

Botox:

• 48-72 hours for effects

• Transcutaneous

  • Laryngeal EMG guided

• Trans-oral or tran-snasal

  • Endoscopy guided

What are the side effects during 3-4 month cycle?

• Side effects can last 2-3 weeks

• Weak, breathy voice

• Rare: Stridor

• Coughing, throat clearing, & laughter are weaker

• ABSD: hoarse voice quality

• Dysphagia in about 30% of cases

• Does NOT migrate to other parts of body

• Spasms will return as effects of Botox wear off

What is a Laryngeal Electromyography (LEMG)?

• a direct measure of laryngeal muscle activity & function

  • Invasive procedure performed by otolaryngologist or neurologist

  • Needle electrodes inserted percutaneously into laryngeal muscles & pattern of electrical activity is studied

  • Vocal tasks used to confirm correct placement in target muscles

What is LEMG used for?

• Diagnosis & prognosis of suspected VF movement disorders including paralysis, paresis, dystonia, & other neuromuscular disorders

• To distinguish unilateral VF paralysis from mechanical fixation of the cricoarytenoid joint

• To guide intramuscular injection of Botox for the treatment of spasmodic dysphonia

What are “Other” Disorders of Voice Use / Laryngeal Dysfunction?

• Signs & Symptoms of:

  • Phonotrauma

  • Vocal Fatigue

  • Muscle Tension Dysphonia (primary MTD V. secondary MTD)

  • Ventricular Phonation

  • Paradoxical Vocal Fold Motion (PVFM)

Muscle Tension Dysphonia (MTD):

• Primary & Secondary

• Reported pain in the larynx, neck, & other areas due to excessive laryngeal tension

What is Primary MTD?

• presence of the disorder without other associated etiology

  • Also referred to as functional dysphonia

What is Secondary MTD?

• maladaptive compensatory voice behaviors that are adopted due to some intruding laryngeal pathology

What are perceptual symptoms of MTD?

• dysphonia, vocal fatigue, loss of pitch & loudness range, reduced vocal flexibility, & strain

How do you treat MTD?

• behavioral voice therapy!