Articulatory Performance in Dysarthria: Using a Data-Driven Approach to Estimate Articulatory Demands and Deficits

This study pursued two goals: (1) to establish range of motion (ROM) demand tiers (i.e., low, moderate, high) specific to the jaw (J), lower lip (LL), posterior tongue (PT), and anterior tongue (AT) for multisyllabic words based on the articulatory performance of neurotypical talkers and (2) to identify demand- and disease-specific articulatory performance characteristics in talkers with amyotrophic lateral sclerosis (ALS) and Parkinson's disease (PD). J, LL, PT, and AT movements of 12 talkers with ALS, 12 talkers with PD, and 12 controls were recorded using electromagnetic articulography. Vertical ROM, average speed, and movement duration were measured. Results showed that in talkers with PD, J and LL ROM were already significantly reduced at the lowest tier whereas PT and AT ROM were only significantly reduced at moderate and high tiers. In talkers with ALS, J ROM was significantly reduced at the moderate tier whereas LL, PT, and AT ROM were only significantly reduced at the highest tier. In both clinical groups, significantly reduced J and LL speeds could already be observed at the lowest tier whereas significantly reduced AT speeds could only be observed at the highest tier. PT speeds were already significantly reduced at the lowest tier in the ALS group but not until the moderate tier in the PD group. Finally, movement duration, but not ROM or speed performance, differentiated between ALS and PD even at the lowest tier. Results suggest that articulatory deficits vary with stimuli-specific motor demands across articulators and clinical groups.