A novel fixed-target task to determine articulatory speed constraints in persons with amyotrophic lateral sclerosis.

PURPOSE: The goal of this study was to determine if talkers with ALS are limited in their ability to increase lower lip and jaw speed at an early stage of the disease when their speaking rate and intelligibility are only minimally or not affected.
METHOD: A novel metronome paced fixed-target task was used to assess movement speed capacities during lower lip and jaw oscillations in seven talkers with ALS and seven age and gender matched controls.
RESULTS: Lower lip peak speeds were significantly lower in talkers with mild ALS than in healthy talkers suggesting a lower lip speed constraint in talkers with mild ALS. Jaw peak speeds tended to be lower, but jaw displacements tended to be larger in talkers with mild ALS than in healthy talkers. Because greater speeds are typically expected for larger displacements, outcomes also suggest a jaw speed constraint in talkers with mild ALS.
CONCLUSIONS: Lower lip and jaw peak speeds may be sensitive measures to identify bulbar motor performance decline at an early stage of the disease when speaking rate and intelligibility are only minimally affected. LEARNING OUTCOMES: The reader will be able to explain two different articulatory strategies to increase speaking rate and understand why fast speech tasks and diadochokinetic pseudo-speech tasks are not suited to assess articulatory speed capacity in healthy and impaired talkers. The reader will also be able to explain how orofacial movement speed capacity can be tested using a fixed-target task and how ALS affects lower lip and jaw speed capacities during the early stages of the disease.