RESUMO
BACKGROUND: Spasmodic dysphonia (SD) is a focal dystonia and adductor SD is the most common form. The standard treatment for adductor SD is EMG-guided, transcutaneous injections of botulinum toxin into the thyroarytenoid muscle. OBJECTIVE: Report the clinical presentation of SD, treatment with botulinum toxin injection, injection technique, results, and adverse effects. MATERIAL AND METHOD: A reviewed of clinical records of patients diagnosed with SD at the Voice Clinic between April 1999 and December 2004 at Srinagarind Hospital, Khon Kaen University, Thailand. Thirty-seven patients were identified but only twenty-five were treated with EMG-guided botulinum toxin injection to the thyroarytenoid muscle. RESULTS: In the presented 37 patients, SD was more common in women (89%) than men (11%). The median duration of symptoms prior to diagnosis was 12 months: all were the adductor type. The average age at onset was 46 years. The presenting symptoms included influence to the voice (84%), hoarseness (70%), strained or strangled voice (65%), decreased loudness (27%), and breathy voice (22%). A vocal tremor coexisted with dystonia in 60% of the presented patients. Treatment with botulinum toxin injection was carried out on 25 patients for 78 injections (mean, 3 per patient). The time for botulinum toxin to take effect averaged 2.3 days (peak effect, 7 days). The patients received substantial relief from their SD symptoms, an average functional improvement of 39.2% (37.6% initially vs. 76.8% finally). Patients' best voice was achieved within one week and persisted for an average of 13.6 weeks. Side effects from the injections included mild breathiness (68%) and mild choking on fluid (56%). After injection, decreased potential for volume was a common complaint, but since all of the patients experienced increased fluency, they were satisfied. Almost all of the patients returned for repeat injections when the benefit diminished. CONCLUSION: Botulinum toxin therapy has become the standard care for the treatment of SD. An acceptable and flexible treatment plan to produce a balance between decreased spasms and loss of function must be developed for each patient.