Evaluation of motor speech function in the diagnosis of various forms of dysarthria

Perceptual analysis is not sufficient enough to identify specific dysarthria types. In order to improve the discrimination between dysarthria types, we developed a standardized evaluation of different functions controlling speech motor performances. This was applied to 90 patients suffering from hypokinetic, spastic or ataxic dysarthria and 15 control subjects. A discriminate analysis showed that 71.4 p. 100 of the cases were correctly classified. This model was validated within a new group of 21 patients and showed that the less severe dysarthric parkinsonian patients were difficult to distinguish from control subjects. The discriminate analysis was then used for 20 patients with atypical parkinsonism. Seven patients with progressive supranuclear palsy were considered to have hypokinetic dysarthria. The 6 patients with multisystem atrophy and 7 with corticobasal degeneration were classified among the 3 dysarthric types. We suggest that motor speech evaluation may contribute to differential diagnosis within groups of patients suffering from atypical parkinsonism.