Optimizing Botox regimens in patients with adductor spasmodic dysphonia and essential tremor of voice: A 31‐ year experience

Objective The purpose of this study was to quantitatively compare the effectiveness of unilateral and bilateral botulinum toxin A (BTX-A) injections for mitigating undesirable weak/breathy voice quality and dysphagia for patients with adductor spasmodic dysphonia and/or essential tremor of voice (ETV). Methods Data were collected from the medical records of 319 patients, yielding three treatment cohorts: patients who received an equal dose bilateral injection regimen (BL=) throughout their course of treatment at VUMC, patients who switched to a unilateral injection regimen (UL), and patients who switched to an unequal dose bilateral injection regimen (BL not equal). Changes in length of improvement, duration of weak/breathy voice, and dysphagia severity were compared. Results The BL = treatment group reported the longest duration of improved voice. Shorter periods of improved voice were reported at baseline by patients who later switched to UL or BL not equal injection regimens. Patients receiving UL injections reported significantly reduced weak/breathy voice and dysphagia. Patients receiving BL not equal injections reported increased length of improved voice; however, dysphagia symptoms increased. Ninety-two percent of patients with ETV switched to a UL regimen, with 61% of patients transitioning within the first three injections. Conclusions Patients with pronounced dysphagia and extended periods of weak/breathy voice may benefit from a UL injection approach to mitigate side effects from BTX-A without sacrificing improved voice outcomes. For patients seeking to extend their length of improved voice, a BL not equal injection regimen may be effective provided the adverse side effects from BTX-A are minimal. Patients with ETV may benefit from a UL injection approach at the outset of their course of treatment with BTX-A. Level of evidence III.