Perceptual characteristics of adductor spasmodic dysphonia

The evaluation of perceptual symptoms is one of the mainstays in the diagno stic workup of adductor spasmodic dysphonia (ADSD). The most widely used pe rceptual rating system is the GRBAS scale. However, with this system, not a ll audible features of ADSD can be described. Therefore, we extended the GR BAS system by 6 parameters. The aim of this study was assessment of the per ceptual characteristics of ADSD with the "extended" GRBAS system and evalua tion of its reproducibility. Seventy-seven patients were scored independent ly by 3 experienced observers quantifying the voice sound profile. Cluster analysis distinguished 3 different voice types. Intraobserver and interobse rver agreement among 8 less-experienced observers appeared fair-to-good. Th is study demonstrates that the "extended" GRBAS system is suitable for perc eptual characterization of ADSD. On the grounds of the fair-to-good interob server variability, it is appropriate for clinical use. Moreover, 4 differe nt voice clusters of ADSD were identified, with significant differences in voice and demographic parameters.