Do perceptual subgroups exist in ataxic dysarthria?

Abstract

When the cerebellar circuit is damaged, the resulting speech disturbance is known as ataxic dysarthria. Features of this disorder include irregular articulatory breakdowns, distorted vowels, excess and equal stress, prolonged phonemes, and abnormal pitch/loudness variation. However, heterogeneity within this disorder has been documented by clinicians and researchers for decades, suggesting that subgroups of ataxic dysarthria may exist. The purpose of this study was to extend this line of research to determine a feasible, reliable perceptual method for identifying and differentiating these proposed subgroups. Two hypotheses were tested based on existing theoretical frameworks: (1) speakers be classified into instability/inflexibility (or mixed presentation) subgroups, and/or (2) speakers be classified into subgroups based on differential speech subsystems involvement. Four dysarthria experts listened to speech samples of adults with ataxic dysarthria and completed rating forms of the speech features. Results suggested that five speakers fit the pattern of instability, two speakers aligned with inflexibility, and one speaker had a mixed presentation. Patterns did not emerge according to differential subsystem involvement. The emergence of subgroups has implications for clinical and research practice; additional research is warranted.