Botulinum toxin treatment of spasmodic dysphonia: Techniques, indications, efficacy

A group of 58 patients with spasmodic dysphonia (SD) was treated perorally or transcutaneously with botulinum toxin (BT), and followed for at least 6 months. Most were treated by peroral injection using indirect laryngoscopy to facilitate precise placement. An effort was made to disperse the toxin over the entire thyroarytenoid muscle in order to affect the greatest number of motor end-plates using the smallest possible effective dose. Severely symptomatic patients with primarily adductor SD had the best results. A potentiation effect is suggested by analysis of a subpopulation of patients, mostly injected unilaterally, for whom the outcome was more favorable for those who had had prior injections. One-month postinjection studies reflect significant improvement in measured readings of a standard passage, and this is consistent with the subjective and perceptual improvements noted. There were no severe complications. Peroral injection seems inadvisable for patients with mixed or abductor SD as well as for those with an uncontrollable gag reflex.