Laryngeal chemodenervation: effects of injection site, dose, and volume

A canine model was used to measure changes in laryngeal adductory pressure (LAP) following injections of vecuronium bromide, a short-acting neuromuscular blocking agent. At a constant volume, LAP was inversely related to the dose (and concentration) of vecuronium injected. At a constant dose (0.05 mg), LAP did not vary significantly over a wide range of injection volumes, from 0.05 to 0.50 mL. At a constant dose and volume, the site of injection was varied among the anterior, middle, and posterior vocal fold, the interarytenoid region, and the anterior contralateral vocal fold. Reduction in LAP was greatest (p<.05) for the posterior vocal fold injection site (78% reduction); less reduction was seen for the middle (54%) and anterior (52%) vocal fold and interarytenoid (43%) injection sites. These results have implications for laryngeal botulinum toxin injections, which are discussed.