Transnasal Endoscopic Injection of Botulinum Toxin in Patients with Adductor Spasmodic Dysphonia

Adductor Spasmodic Dysphonia (ADSD) is the most common form of spasmodic dysphonia. It encompasses various symptoms affecting voice and speech. The objective of this study is to report the management of patients with ADSD using the transnasal endoscopic approach for laryngeal Botulinum Toxin (Botox) injection.

A retrospective chart review of patients with ADSD who underwent transnasal endoscopic laryngeal Botox injection was conducted. Voice outcome measures included the Voice Handicap Index-10 (VHI-10) score and the degree of speech fluency.

Eight patients with ADSD who underwent 20 office-based transnasal endoscopic laryngeal Botox injections were included. The most commonly injected sites were the thyroarytenoid muscle (TA) and the false vocal fold in 95% and 55% of the cases, respectively. The mean dose of injected Botox was 2.48 ± 0.55 IU in the TA muscle, and 2.14 ± 0.53 IU in the false vocal fold. The mean amount of Botox injected in the larynx was 7.16 ± 2.42 IU. The mean follow-up period was 17.7 ± 13.3 months. There was marked improvement in speech fluency in 64.7% of the cases and mild improvement in one third of the cases. Marked improvement in speech fluency was recorded in 64.7% of the cases and mild improvement in one third of the cases. The mean VHI-10 score of patients dropped significantly from 22.47±4.08 to 15±4.69 following treatment (p<0.001).

The transnasal endoscopic approach is an effective and well-tolerated approach for laryngeal Botox injection in patients with ADSD.