Technique for injection of botulinum toxin through the flexible nasolaryngoscope.

A new endoscopic method of injecting botulinum toxin into the thyroarytenoid muscles for treatment of adductor spasmodic dysphonia was evaluated. Twelve patients with adductor spasmodic dysphonia were given injections in the thyroarytenoid muscle under video visualization with a flexible catheter needle that was passed through the working channel of a flexible nasolaryngoscope. Six patients received unilateral injections, and six received bilateral injections. Preinjection and postinjection speech samples were compared by use of spectrographic analysis. Significant decreases in voice breaks and sentence duration were found after treatment with both unilateral and bilateral injections. Patient interviews and diaries documented the reported degree and duration of symptom reduction. All 12 patients reported that the injections were of significant benefit and that the endoscopic procedure was tolerable. We concluded that this is a safe and effective technique for injecting botulinium toxin into laryngeal muscles for treatment of spasmodic dysphonia.