The Effects of Botulinium Toxin in Vocal Nodules

Abstract

Background and ObjectivesZZVocal nodules are the most common voice disorder due to vocal misuses. Vocal nodules are primarily treated with voice therapy and are rarely removed through laryngomicrosurgery. Although the rate of recovery for individual patients may vary, 60-70% of them are fully treated. Because vocal nodules have many possible causes, 30-40% of patients remain untreated. Also, vocal nodules recurrence after the surgical treatment is sometimes observed. The author claims that incomplete contact between vocal cords during phonation is a major cause of the vocal nodules. Most vocal nodules do occur from incomplete contact between vocal cords during phonation, and various voice therapies are designed to improve habitual misuses of the vocal cords. However, vocal nodules tend to remain unhealed unless patients change their habitual misuses of the vocal cords. The cricothyroid muscle tension is known to hinder the contact between vocal cords. The author injected a restricted amount of botulinium toxin to the cricothyroid muscle to reduce the muscle tension and observed changes in vocal cords’ movement. Subjects and MethodZZIn this study, the author injected botulinium toxin to the cricothyroid muscle of 21 patients. For 2-4 weeks, we observed patients’ responses to the treatment, by measuring changes in subglottal pressure, mean air flow rate, maximum phonation time, jitter, shimmer, noise-to-harmonic ration of patients and subjective evaluation of voice changes. In addition, the author conducted stroboscopy to evaluate the usefulness of the treatment. ResultsZZThe improvement was in the subjective evaluation of voice changes and stroboscopic findings. ConclusionZZThe observation demonstrated a great improvement in vocal nodules after the injection of botulinium toxin into the cricothyroid muscle.