Perceptual ratings of subgroups of ataxic dysarthria

The speech characteristics of ataxic dysarthria are known to be quite diverse. The varied presentation of this dysarthria challenges researchers and clinicians alike, and brings into question whether it is a single entity. While the possibility of subtypes of ataxic dysarthria has been suggested, the nature of these putative groups remains unclear.

The purpose of this pilot study was to determine if perceptual speech characteristics would align with a pattern of unusual variability or unusual consistency across speech subsystems and speaking tasks.

A framework of speech characteristics was created from the existing literature that clustered speech attributes according to notions of instability (unusual variability) or inflexibility (unusual consistency). These speech features were used to develop a perceptual rating form. Ten experienced speech-language pathologists listened to pre-recorded, exemplary samples of 10 speakers with ataxic dysarthria and rated the perceptual speech features.

Results suggested that five speakers fit the pattern of instability, one speaker aligned with inflexibility and four speakers had a mixed presentation. Intra-rater reliability was satisfactory.

This study adds to the sparse, yet growing, literature to support the existence of subgroups in ataxic dysarthria. The more frequent occurrence of the instability profile is consistent with primary disruption to the timing function of the cerebellar circuit. Identification of subgroups has important clinical and research implications and further research is warranted.