Treatment of Adductor Spasmodic Dysphonia with Botulinum Toxin

Abstract

Background and Purpose: The aim of our study is to evaluate the effect of botulinum toxin in patients of adductor spasmodic dysphonia (SD) with and without voice tremor. Methods: We used botulinum toxin A (BTX-A, Botox®) in treating 10 patients with adductor SD. Among them, 6 patients were presenting simple adductor SD, 4 patients were presenting adductor SD and prominent voice tremor. The features of their voices were evaluated blindly by another neurologist, by a speech pathologist, and by an otolarygologist with direct videoendoscopic observation before and after treatment. Guided with EMG, a dose of 15 to 20 units of BTX-A was injected into the unilateral thyroarytenoid muscle. Results: We obtained a significant improvement of voice quality in 5 out of 6 simple adductor SD patients. The benefits commenced at a mean of 5 days (range; 4-6 days). The median duration of peak effects was 4 weeks (range: 3-6 weeks). The remaining 1 patient had only mild effects. The videoendoscopic parameters also showed a significant improvement in correlation with the clinical effect. Four adductor SD patients associated with dominant voice tremor did not improve, especially in the tremor component. Conclusion: We have proved that BTX-A is an effective treatment for simple adductor SD, but not for adductor SD with prominent voice tremor. We suggest that a videoendoscopic evaluation is valuable for selecting the patients with adductor SD, particularly complicated with voice tremor.