Comparison between Essential Vocal Tremor and Dystonic Vocal Tremor Treated with Botulinum Toxin and Propranolol

Objectives: Determine and compare the response to treatment with intramuscular botulinum toxin and oral propranolol on vocal tremors, essential and dystonic. Methods: Randomized clinical trial between January 2012 and September 2013. Fifteen patients with vocal tremor were divided into 2 groups: essential and dystonic vocal tremor. Both groups were treated with botulinum toxin in thyroarytenoid muscle (15 units of Dysport unilaterally) and propranolol (80 to 120 mg daily) at different times. Time to “wash out” after injection of 6 months and after propranolol 2 months. Patients underwent self-assessment of vocal improvement, nasofibroscopy larynx, perceptual, and acoustic analysis of voice before and after each treatment. Data were compared according to the type of tremor and treatment and subjected to statistical analysis (significance level of .05). Results: There was statistically significant improvement in perceptual measure of vocal instability in patients with dystonic tremor after treatment with botulium toxin, compared with propranolol (P = .028). The acoustic measurement variabiity of fundamental frequency was also statistically significant, with a decrease in the treatment of dystonic tremor in connection with the botulinum toxin compared with propranolol (P = .05) and before treatment (P = .011). Conclusions: The dystonic and essential tremors differ in responses to treatment. The dystonic tremor responds positively to the injection of botulinum toxin into the thyroarytenoid muscle, but not to the use of oral propranolol.