What is the recommended management for laryngeal dystonia?

Management of Laryngeal Dystonia

Botulinum toxin injections are the first-line treatment for laryngeal dystonia, providing significant improvement in voice quality and quality of life for 3-6 months before requiring repeat treatment. 1

Understanding Laryngeal Dystonia

Laryngeal dystonia is a focal dystonia characterized by involuntary spasms of the laryngeal muscles, most commonly presenting as spasmodic dysphonia (SD). It typically manifests in two main forms:

• Adductor SD (most common): Characterized by a strained, strangled voice with breaks in vocal flow during vowels and voiced consonants
• Abductor SD: Characterized by voice breaks during voiceless consonants, resulting in breathy or whispered speech

Other less common manifestations include:

• Dystonic respiratory stridor
• Dystonic cough
• Dyscoordinate breathing
• Paroxysmal hiccups or sneezing 2

Diagnostic Approach

Diagnosis is often delayed (averaging 4.4 years) as laryngeal dystonia can masquerade as other forms of dysphonia. Key diagnostic features include:

• Task-specific phonemic dysphonia
• Increased tone and voice breaks in intralaryngeal muscle groups
• Normal laryngoscopic findings during non-phonatory tasks
• Symptoms that worsen with specific vocal tasks

Treatment Algorithm

First-Line Treatment:

• Botulinum toxin injections into affected muscles 1
  • Mechanism: Causes transient, nondestructive flaccid paralysis by inhibiting acetylcholine release
  • Efficacy: Improves voice in 70-90% of patients
  • Duration: Effects last 3-6 months before requiring repeat treatment
  • Target muscles:
    • Adductor SD: Thyroarytenoid/vocalis muscles
    • Abductor SD: Posterior cricoarytenoid muscles

Injection Technique:

• Can be performed under EMG guidance
• Can be done in office under local anesthesia or in operating room under general anesthesia
• Dosing has decreased over time (from 2.3 units to 0.5 units between 1991-2011) 2

Expected Outcomes:

• Improvement typically occurs within 24-72 hours
• Patients improve to approximately 70-90% of normal function 3
• Treatment effects last 2-14 months (average 4 months) 4

Common Side Effects:

• Breathy hypophonia (typically lasting 1-2 weeks)
• Mild sensation of choking/aspiration with fluids (typically lasting a few days)
• Dysphonia secondary to vocal cord paresis (occurs in about 38.7% of treatments) 2

Special Considerations

Factors Affecting Treatment Response:

• Better outcomes typically seen in:
  • Adductor SD
  • Patients with stridor
  • Patients without extra-laryngeal dystonia 2

Treatment of Abductor SD:

• May require bilateral injection of posterior cricoarytenoid muscles
• Some patients may also need cricothyroid muscle injections 5
• Average improvement to 70% of normal voice function
• Patients with vocal tremor, other dystonia, or respiratory dysrhythmia tend to have less improvement 5

Alternative Approaches

For patients who fail botulinum toxin therapy or have contraindications:

• Surgical options: Laryngeal framework surgery or medialization techniques may be considered for certain cases of glottic insufficiency 1
• Voice therapy: May provide adjunctive benefit but is generally not sufficient as monotherapy

Monitoring and Follow-up

• Regular follow-up to assess treatment response and need for repeat injections
• Documentation of resolution, improvement, or worsening of symptoms after treatment 1
• Monitoring for side effects, particularly after initial injections

Important Caveats

• Botulinum toxin provides symptom control but is not curative as laryngeal dystonia is a central nervous system disorder 1
• Technical failures with injections are rare (approximately 1.1%) 2
• Patients should be informed about the need for repeated treatments
• Polytetrafluoroethylene should not be used as a permanent injectable implant due to risk of foreign body granulomas 1