Botulinum toxin A injection under electromyographic guidance for treatment of spasmodic dysphonia.

Spasmodic dysphonia is a disabling voice condition caused by a chronic neurological disorder of central motor processing. Present therapy is directed at relief of symptoms rather than cure. Botulinum toxin type A injection into the thyroarytenoid muscle has become the pre-eminent approach for treatment of adductor spasmodic dysphonia. Botulinum toxin A injections can be performed in an out-patient setting under electromyographic guidance. We present our experience with 153 injections in 14 patients with adductor spasmodic dysphonia over a 10-year period. We demonstrate that the electromyography signal is a reliable prognostic indicator in terms of efficacy, and that patients' subjective opinion is a valid indicator of treatment success and future treatment strategy.