Analysis of abnormal articulatory dynamics in two dysarthric patients.

By means of pellet tracking techniques using an X-ray microbeam system, observations of the articulatory movements of various types of dysarthric subjects were conducted. In selected cases, electromyography (EMG) was also performed. The data were specifically examined for range, velocity, and consistency (reproducibility) of the movements of the articulators, as well as the pattern of coordination of the different articulators involved. It was found in the case of ataxic dysarthria of cerebellar origin, for example, that the dynamic patterns were best represented as a difficulty in the initiation of purposeful movements and an inconsistency of articulatory movements, particularly in the repetitive production of a monosyllable. On EMG, breakdown of the rhythmical patterns in the articulatory muscles was quite obvious in the repetition of a monosyllable. In the case of amyotrophic lateral sclerosis (ALS), decrease in the range and velocity of movements was noted. This resulted from reduced neuromuscular units (NMU) activities manifested in clinical EMG. Analysis of the dynamic aspects of the dysarthrias is a promising approach for elucidating the nature of central problems of speech production and for a differential diagnosis of various types of dysarthrias.