Clinical Application of Botulinum Toxin to Functional Dysphonia

ABSTRACT

Functional dysphonia (FD) is a disease entity which includes various voice disorders in the absence of structural or neurologic laryngeal pathology. Muscle tension dysphonia (MTD), psychogenic dysphonia are representative FD with completely different pathogenesis. Therefore there is no standard treatment modality for FD, the first step of treatment of FD is differentiating patient's voice symptoms from other organic voice disorders and other functional voice problems. MTD is a functional voice disorder caused by hyperfunction of intrinsic and extrinsic laryngeal musculature. Symptoms include increased vocal effort, roughness, fatigue and odynophonia. First line for MTD is indirect or direct voice therapy. Unfortunately, many patients with MTD improve with voice therapy alone. For these patients, various modalities tried; lidocaine application, surgical excision of the false vocal folds, and botulinum toxin injection, etc. Botulinum toxin injections are widely used in the field of otolaryngology, especially for spasmodic dysphonia. However, its use in FD or MTD has only been described in few case reports. The aim of this lecture is to evaluate the feasibility of botulinum toxin injection for FD, especially MTD.