Abstract
The scientific posters provide an opportunity for visual presentation of charts, drawings, and photographs, supplemented with 1 or 2 pages of text. Authors will post the times they will be available for questions. The posters will be available Sunday to Tuesday, September 21–23, from 7:00 am to 8:00 pm in Hall A4 of the Orange County Convention Center.
Objectives: Adductor spasmodic dysphonia, the most common form of laryngeal dystonia, is a debilitating and often disabling problem. Botulinum toxin has been shown to be successful in providing symptomatic relief, but the optimal dosing regimen has not been firmly established. Botulinum toxin is a potent neuroparalytic agent. Potency is expressed in mouse units, where 1 unit is the median lethal dose (LD50) for mice. Most physicians deliver doses between 0.5 and 15 units for spasmodic dysphonia. The purpose of this study is to determine the dose of botulinum toxin that maximizes duration of benefit and minimizes side effects.
Methods: A retrospective chart review was done on 1503 injections performed by the senior author at a single institution over a period of 11 years. A multivariate analysis was performed examining dose, length of benefit, and severity of side effects. Both unilateral and bilateral injections were included.
Results: The optimal dose of botulinum toxin was determined to be 3.75 to 5 units for unilateral injections and 1.25 to 2.5 units for bilateral injections. The mean duration of benefit was 5.8 months for unilateral and 5.4 months for bilateral injections. Doses greater than these did not significantly lengthen the duration of benefit but were associated with greater severity of side effects including excessive breathy hypophonia, aspiration, and dysphagia.
Conclusion: Adductor spasmodic dysphonia is optimally treated with botulinum toxin using relatively low doses. Higher doses commonly used in the past do not provide greater length of benefit and are associated with higher complication rates.