Chemodenervation of the Larynx

Abstract

Botulinum neurotoxin (BoNT) has existed for thousands of years; however, it was not medically utilized until investigations into its therapeutic use began in sincerity during the late 1970s and 1980s. This, coupled with the reclassification of spasmodic dysphonia as a focal dystonia, led to the use of chemodenervation for this disorder, which has since become a refined technique. Indeed, due to its safety and efficacy, BoNT has been investigated in multiple neurolaryngology disorders, including spasmodic dysphonia, vocal tremor, and muscle tension dysphonia. BoNT has been shown to be a useful and safe adjunct in the treatment for these disorders and may reduce or eliminate oral pharmacotherapy and/or prevent the need for a surgical intervention. We present the historical background, development, proposed mechanisms of action, uses, and techniques for administering BoNT for laryngeal disorders, with a particular focus on spasmodic dysphonia.

Keywords: botulinum toxin; chemodenervation; laryngeal tremor; muscle tension dysphonia; spasmodic dysphonia; vocal tremor.

Figure 1

Sagittal cross-section schematic of the larynx at the midline, showing relevant bones, cartilage, ligaments, and muscles.

Figure 2

Thyroarytenoid muscle injections through different approaches: (A) cricothyroid approach; (B) thyrohyoid approach; (C) peroral approach.

Figure 3

Supraglottic injection via thyrohyoid membrane approach.

Figure 4

Posterior cricoarytenoid muscle injection via cricothyroid/transglottic approach.

Figure 5

Interarytenoid muscle injection via the cricothyroid membrane approach.