Comparison of botulinum toxin and propranolol for essential and dystonic vocal tremors

OBJECTIVES

Vocal tremors, which cause social difficulties for patients, may be classified as resting or action tremors. Of the vocal action tremors, essential and dystonic tremors are the most common. Botulinum toxin and oral medications have been used to treat vocal tremors, but no comparative clinical trials have been performed. The aim of this study was to compare the effects of botulinum toxin injection and the oral administration of propranolol in the treatment of essential and dystonic vocal tremors.

METHODS

This clinical trial recruited 15 patients, divided into essential and dystonic vocal tremor groups. Patients in both groups received successive treatment with botulinum toxin and propranolol. The treatments were administered at different times; the order of treatment was randomly selected. Patients were assessed with flexible nasofibrolaryngoscopy and with perceptual and acoustic voice evaluations. A statistical significance level of 0.05 (5%) was used.

RESULTS

Botulinum toxin produced statistically significant improvements in perceptual measures of vocal instability in patients with dystonic vocal tremors compared with baseline values and treatment with propranolol. The acoustic measure of variability in the fundamental frequency was significantly lower in patients with dystonic vocal tremors after treatment with botulinum toxin.

CONCLUSION

Essential and dystonic vocal tremors responded differently to treatment. Dystonic vocal tremors responded significantly to treatment with botulinum toxin but not oral propranolol. Essential vocal tremors did not respond significantly to either treatment, perhaps due to the small number of patients, which is a limitation of this research.

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.

Laryngeal electromyography in dysphonic patients with incomplete glottic closure

The lack of specificity in laryngoscopical examination requires that the diagnosis of superior laryngeal and recurrent laryngeal nerve involvement be carried out with the aid of electromyography.

Objective

This study aims to assess the electrophysiological function of the superior and inferior laryngeal nerves by measuring the electrical activity of the muscles they innervate in dysphonic patients with incomplete closure of the vocal folds during phonation.

Method

Thirty-nine patients with incomplete glottic closure were enrolled in a prospective study and had their cricothyroid, thyroarytenoid, and lateral cricoarytenoid muscles examined bilaterally through electromyography. Insertion activity, electrical activity at rest (fibrillation, positive wave and fasciculation) and during muscle voluntary contraction (recruitment, amplitude, potential length and latency between electrical activity and phonation) were measured.

Results

No altered test results were observed for parameters insertion activity and electrical activity at rest. None of the patients had recruitment dysfunction. The mean electrical potential amplitude values were within normal range for the tested muscles, as were potential durations and latency times between the onset of electrical activity and phonation.

Conclusion

No signs of denervation were seen in the thyroarytenoid, cricothyroid, and lateral cricoarytenoid muscles of the studied patients.