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

Abstract

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.

Copyright © 2011 Elsevier Inc. All rights reserved.

Figures

Figure 1

Individual speaking rates (panel A) and articulatory rates (panel B) of each talker with ALS. The mean of controls is marked in each panel by a black solid line. The dashed lines represent one standard deviation above and below the control group’s mean.

Figure 2

Marker placement and experimental set-up during the jaw fixed-target task. During the lower lip fixed-target task, the strike object was places underneath the lower lip, a bite block was used to prevent the jaw from moving, and the small reflective sphere was replaced by a similar sized flat reflective marker.

Figure 3

Time history of the 3-D Euclidian distance between the right top head marker and right jaw marker. Only the ten largest displacements were selected for data analysis during the jaw and lower lip fixed-target tasks.

Figure 4

Mean peak speeds (+SE) of talkers with mild ALS and controls during the jaw fixed-target task (Jaw) and lower lip fixed-target task (Lower lip).

Figure 5

Mean peak speeds (+ SE) of the jaw and lower lip for talkers with mild ALS and controls as well as individual data of two talkers with severe ALS.

Figure 6

Mean maximum displacements (+ SE) of the jaw and lower lip for talkers with mild ALS and controls as well as individual data of two talkers with severe ALS.

Figure 7

Mean movement durations (+ SE) of the jaw and lower lip for talkers with mild ALS and controls as well as individual data of two talkers with severe ALS. The expected movement durations are also shown as a function of metronome pace.