Initial Dosing of Botox A in Adductor Spasmodic Dysphonia.

Objective: 1) Assess effect on voice improvement and duration of breathiness based on initial dose of BotoxA in management of adductor spasmodic dysphonia. 2) Compare voice outcomes for initial bilaterally injected doses of 1.25 units Botox A (Group A) versus 2.5 units (Group B). Method: A retrospective chart review was undertaken of all adductor spasmodic dysphonia patients treated at a tertiary care facility between 1990 and 2011. Demographic data (age and sex), voice rating, duration of voice improvement, and breathiness were evaluated and compared between Groups A and B using Student's t test and chi-square analysis. Results: Of 478 patients identified, 305 (group A: 223; group B: 82) patients met inclusion criteria. The average age of group A was 56.2 years and group B was 57.4 years (P = .5). The female/male ratio was 2.91 for group A versus 3.56 for group B (P = .61). Good voice outcomes (grade 3 or 4) were reported by 91% of group A patients versus 94% of group B (P = .75). The average duration of voice improvement was 99.7 days for group A and 108.3 for group B (P = .54). The average duration of breathiness was 10.88 days for group A versus 15.42 for group B (P = .02). Conclusion: Patients injected with 1.25 units bilaterally had a statistically significant shorter duration period of breathiness without a statistically significant difference in clinical effectiveness or voice outcome. It is therefore recommended that a relatively low initial Botox dose be used with subsequent titration to achieve improved voice outcomes.