Dharia I, et al. - Given that the primary treatment of adductor spasmodic dysphonia is repeated injections of botulinum toxin type A (Botox) into the thyroarytenoid muscles, researchers conducted this retrospective study to assess the treatment effect and side effect profile across a large number of injections. This investigation was conducted previously in 2002 on 45 patients. The sample consisted of all patients (n = 272) with adductor spasmodic dysphonia with and without tremor treated by the senior laryngologist at George Washington University. In total, 4,023 injections (2,708 bilateral and 1,315 unilateral) were assessed in this study. This research reveals that in producing optimal effect/side effect profiles, bilateral injections of Botox are more effective.