THE SWALLOWING SIDE-EFFECTS OF BOTULINUM TOXIN TYPE-A INJECTION IN SPASMODIC DYSPHONIA

Botulinum toxin type A (BOTOX (R)) injection of the thyroarytenoid mus cle is used to control speech symptoms in patients with adductor spasm odic dysphonia. Transient difficulty in swallowing liquids is a common treatment side effect. Laryngeal movement durations were measured dur ing swallowing in 13 adductor spasmodic dysphonia patients undergoing treatment and in 6 normal control subjects in order to determine the f ollowing: 1. whether, prior to the injection, laryngeal movement durat ions were longer in the spasmodic dysphonia patients than in the contr ol subjects; 2. whether movement durations increased following the inj ections; 3. whether preinjection swallowing difficulties related to po stinjection swallowing measurements and postinjection patient reports of swallowing problems. A piezoelectric movement transducer was shown to be accurate for noninvasive measurement of laryngeal movement durat ion in relation to muscle onset and offset for hyoid elevation and rel axation. Before botulinum toxin type A injection, no significant diffe rences in swallowing duration were found between the patient and contr ol groups. Pour patients with swallowing complaints prior to injection had longer laryngeal movement durations than the other spasmodic dysp honia patients and the control subjects. Following injection, laryngea l movement durations increased in the patients with spasmodic dysphoni a, and eight patients reported dysphagia for an average of 2 weeks. Re lationships were found between the patients' initial reports of swallo wing problems and increased laryngeal movement durations before and af ter botulinum toxin type A injection. Those patients initially reporti ng swallowing difficulties had severe dysphagia for 2 weeks after the injection. Patient reports of dysphagia prior to injection may indicat e a greater likelihood of significant dysphagia following thyroaryteno id injection with botulinum toxin type A.