ANALYSIS OF FACTORS AFFECTING BOTULINUM TOXIN RESULTS IN SPASMODIC DYSPHONIA

This study was designed to investigate how variations in patterns of i njection could improve the efficacy of botulinum toxin injections in r elieving the symptoms of adductor spasmodic dysphonia, A total of 64 a dductor spasmodic dysphonia patients who were injected using indirect laryngoscopic localization (for a total of 426 injections) were analyz ed retrospectively using their own subjective data on duration of voic e improvement, optimal voice improvement, breathiness side effects, an d intervals between treatments. Injection to both the thyroarytenoid ( TA) and the lateral cricoarytenoid (LCA) simultaneously gave the best voice results; the overall improvement from baseline was the longest l asting, and the period during which the voice was the best was the lon gest lasting. TA + LCA also gave the shortest duration of undesirable breathiness side effect. On the basis of these data, it seems reasonab le to recommend that initial botulinum toxin therapy for adductor spas modic dysphonia patients should be a single unilateral injection place d strategically at the posterior portion of the TA and directed toward the LCA so that both muscle groups are affected.