Tongue Strength and Speech Intelligibility in Oculopharyngeal Muscular Dystrophy.
Tongue weakness is presumed to contribute to reduced articulatory precision and speech intelligibility, but studies of dysarthric speakers do not consistently find a correlation between decreases in maximal tongue strength and speech measures. In this study, estimates of maximal tongue strength and tongue pressure during the syllable [TEXT NOT REPRODUCIBLE IN ASCII] were obtained from eight persons with oculopharyngeal muscular dystrophy (OPMD). This disorder, characterized by oral, facial, and pharyngeal weakness related to slowly progressive muscle cell loss is sometimes accompanied by flaccid dysarthria. The individuals with OPMD had significantly reduced maximal tongue strength compared to normal controls but achieved nearly normal levels of tongue pressure during the speech task. They did not display deficits in articulatory precision or speech intelligibility, but they did have slow diadochokinetic rates for [TEXT NOT REPRODUCIBLE IN ASCII] and increased pause time in short sentences. The ability to achieve lingual pressures needed for speech sounds resulted in preserved speech intelligibility, but the increased proportion of maximal strength required to produce speech may result in slower speech movements. **********