A physiological analysis of the articulatory function of 16 adults with multiple sclerosis (MS) was performed using lip and tongue transduction systems. Sixteen nonneurologically impaired adults, matched for age, gender, and education, served as controls. The MS speakers demonstrated patterns of tongue function that were significantly different from those of the control speakers. Specifically, the MS speakers had significantly reduced tongue strength, endurance, and rate of repetitive movements. In addition, preclinical signs of lingual dysfunction were evident in nondysarthric MS speakers on endurance and rate tasks when compared to control subjects. These physiological findings could account for the perceptual findings of impaired articulation and reduced intelligibility. No lip dysfunction was revealed through either the physiological or the perceptual assessments.
The authors are with the Motor Speech Research Unit, Department of Speech Pathology & Audiology, The Univetsity of Queensland, Brisbane 4072, Australia.