Adductor spasmodic dysphonia: standard evaluation of symptoms and severity.

Description and quantification of the symptoms of adductor spasmodic dysphonia often reflect the clinician's knowledge of the disorder, ideas about the cause of the disorder, and personal experience. No reliable instrument that identifies and quantifies the spectrum of perceptual symptoms has been available. Therefore, we developed a standardized measure called the Unified Spasmodic Dysphonia Rating Scale (USDRS) in cooperation with a team of 118 experienced voice judges. Consensual validations of content validity guided the incremental development of the scale. Using the USDRS allows more consistent and complete data collection, both clinically and in research clinical trials.