A Novel Technique: Ultrasonography-Guided Botulinum Toxin Injection in Adductor Type Spasmodic Dysphonia

Abstract

Spasmodic dysphonia (SD) is a rare disease caused by focal dystonia in the laryngeal muscles. The adductor type SD (AdSD), which affects the thyroarytenoid (TA) muscle, is found in 80% of all SD patients. For them, voice therapy and medication are less effective and definitive surgical treatment has not been established yet. Botulinum toxin injection is considered the gold standard treatment. However, patients require regular injections every 3-6 months whenever the effect of botulinum toxin disappears. Therefore, it is essential that injecting botulinum toxin is safe, comfortable, and accurate. Injections are usually performed under the guidance of electromyography or laryngoscopy. Ultrasonography (US) is a familiar device to otorhinolaryngologists and has recently been used to evaluate the laryngeal structures. While US has been used only for diagnosis, it can also be used for treatment. Here, we describe a novel technique that can be used to inject botulinum toxin into the TA muscle via trans-cartilaginous approach under the guidance of US for the treatment of AdSD.