Examination of Perceptual Subgroups of Ataxic Dysarthria Through Auditory Free Classification

Abstract

Ataxic dysarthria is highly heterogeneous in its presentation (Duffy, 2020). While the most salient and distinguishing perceptual characteristics center on articulatory and prosodic abnormalities, the manifestation can be quite variable. In fact, some characteristics are even contradictory in nature, such as prosodic excess and prosodic insufficiency. This perceptual heterogeneity has prompted research into possible subgroups within ataxic dysarthria. The current study expands upon the extant literature (e.g., Spencer, Amaral, and Lansford, 2022) which contends that subgroups are mediated by different patterns of motor control, namely an unstable pattern and an inflexible pattern (see Hartelius et al., 2000). In the present study, 25 speakers with ataxic dysarthria from a range of etiologies provided speech samples during two tasks: alternating motion rates (AMR) and connected speech (55 syllables from a reading sample). Seventeen experienced speech-language pathologists served as listeners and completed an auditory free-classification task (Clopper, 2008). Listeners grouped speakers who sounded similar based on their own judgment of the most salient perceptual characteristics. Listener ratings were compared with a priori expert determinations of speakers who fit the instability subgroup profile, the inflexibility subgroup profile, or a mixed subgroup of the two profiles. Results contributed to the existing evidence of perceptually distinct subgroups in ataxic dysarthria, and argue for continued investigation. The findings have implications for models of cerebellar disruption and can inform clinical diagnostic and treatment practices.