Bilateral Thyroarytenoid Denervation: A New Treatment for Laryngeal Hyperadduction Disorders Studied in the Canine

Abstract

Adductor spasmodic dysphonia is a vocal disorder of uncertain etiology with no satisfactory long-term treatment. Recently, injection of botulinum toxin (Botox) into the thyroarytenoid (TA) muscle has been used as an effective temporary treatment. A surgical counterpart to bilateral TA Botox injection is described in this article. Bilateral thyroarytenoid denervation was performed through a window in the thyroid cartilage in seven canines, including four that were studied 3 months after the procedure. No serious complications occurred in the animals, each maintaining full vocal fold abduction and adduction. In all cases, anticipated physiologic changes in laryngeal function were observed, including the inability to generate high subglottic pressures during high levels of laryngeal nerve (RLN) stimulation. In two of the surviving animals, the ansa cervicalis was used to reinnervate the TA muscle, thereby preventing the possibility of reinnervation from the proximal RLN stump while limiting TA atrophy and fibrosis. Bilateral TA denervation represents a hopeful new long-term approach to spasmodic dysphonia treatment.