Spasmodic Dysphonia

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Definition & Basics - Voice Interrupted

  • Spasmodic Dysphonia (SD): A chronic neurological voice disorder; specifically a focal laryngeal dystonia.
  • Nature: It's task-specific, primarily affecting speech, and is action-induced.
  • Mechanism: Characterized by involuntary, spasmodic contractions of laryngeal muscles during voice production.
  • Voice Quality: Results in a strained, tight, choked, or breathy voice; often with voice breaks. Singing or laughing may be unaffected.

    ⭐ SD is often misdiagnosed as muscle tension dysphonia or psychogenic voice disorder, delaying appropriate treatment. Anatomy of the larynx and vocal folds

Pathophysiology & Etiology - Brain's Vocal Glitch

  • Neurological Origin: Considered a focal laryngeal dystonia; not a psychogenic disorder.
  • Core Defect: Basal ganglia dysfunction (e.g., putamen, globus pallidus) leading to faulty sensorimotor integration for precise voice modulation.
  • Etiology Spectrum:
    • Predominantly idiopathic (most common).
    • Genetic predisposition: Rare, but familial cases exist.
    • Possible Triggers: Upper Respiratory Infections (URI), significant stress, or prolonged voice overuse can precipitate onset in susceptible individuals. Brain areas and pathways involved in speech production

⭐ Though neurological in origin, structural brain imaging (MRI/CT) is typically normal in Spasmodic Dysphonia.

Types & Clinical Features - Strained or Breathy?

Spasmodic Dysphonia (SD) presents primarily in three forms based on laryngeal muscle involvement:

FeatureAdductor SD (ADSD)Abductor SD (ABSD)
Voice QualityStrained, strangled, effortfulBreathy, whispery, weak
Voice BreaksOn voiced sounds (e.g., vowels, /z/)On voiceless sounds (e.g., /s/, /p/)
  • Mixed SD: Features of both ADSD and ABSD.
  • Task Specificity: Symptoms are typically worse during connected speech and often improve or disappear during activities like singing, laughing, or shouting.

⭐ Adductor Spasmodic Dysphonia (ADSD) is the most common type, accounting for approximately 80-90% of cases.

Diagnosis - Pinpointing the Spasms

  • Clinical History: Detailed patient interview focusing on voice symptoms.
  • Perceptual Voice Assessment: Subjective evaluation of voice quality (e.g., GRBAS scale).
  • Flexible Nasolaryngoscopy: To visualize vocal fold movement and identify spasms during speech.
    • Adductor SD: Cords slam shut.
    • Abductor SD: Cords open inappropriately.
  • Laryngeal Electromyography (LEMG): Confirmatory test showing excessive, involuntary laryngeal muscle activity.

    ⭐ Laryngeal Electromyography (LEMG) is the gold standard for confirming SD, especially in ambiguous cases.

  • Acoustic Analysis: Objective measures of voice parameters (jitter, shimmer, voice breaks).
  • Rule Out: Exclude other neurological or structural voice disorders.

Vocal Fold Spasms in Spasmodic Dysphonia

Management - Taming the Tremors

  • Botulinum Toxin (Botox) Injections: Mainstay treatment. 📌 Botox: Bottles Toxic spasms.
    • Provides temporary relief (3-4 months).
    • Target Muscles:
      • Adductor SD (ADSD): Thyroarytenoid (TA) muscle - 1.25-2.5 U.
      • Abductor SD (ABSD): Posterior Cricoarytenoid (PCA) muscle - 2.5-10 U.

    ⭐ Botulinum toxin injection into laryngeal muscles is the current gold standard treatment for Spasmodic Dysphonia, providing symptomatic relief for 3-4 months.

  • Voice Therapy: Adjunctive role; helps manage symptoms and optimize voice post-Botox.
  • Surgical Options (Limited Use/Controversial):
    • Recurrent Laryngeal Nerve (RLN) denervation-reinnervation.
    • Selective Laryngeal Adductor Denervation-Reinnervation (SLAD-R).
    • Thyroplasty Type II (for ABSD).

Botox injection into the thyroarytenoid muscle

High‑Yield Points - ⚡ Biggest Takeaways

  • Spasmodic Dysphonia (SD) is a focal laryngeal dystonia; etiology often unknown.
  • Two main types: Adductor SD (common, strained-strangled voice) and Abductor SD (breathy, whispery voice).
  • Voice is task-specific: worsens with speech, often improves with laughing or singing.
  • Diagnosis is primarily clinical, aided by laryngoscopy showing vocal fold spasms.
  • Botulinum toxin (Botox) injections are the mainstay of treatment.
  • Adductor SD: Botox into thyroarytenoid (TA) muscle.
  • Abductor SD: Botox into posterior cricoarytenoid (PCA) muscle.

Practice Questions: Spasmodic Dysphonia

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Flashcards: Spasmodic Dysphonia

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What is the treatment for puberphonia?_____

Speech therapy

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