DYSARTHRIA IN FRIEDREICHS ATAXIA - TIMING OF SPEECH SEGMENTS

Under certain conditions Friedreich's ataxia (FA) can be considered a model of afferent cerebellar dysfunction. In seven subjects suffering from FA acoustic analysis of sentence utterances, including durational measurements of syllables and intrasyllabic segments, was performed. The FA patients presented with prolongation of syllable, vowel and occlusion lengths. Furthermore, they showed less durational contrasts between stressed and unstressed syllables. These abnormalities may be explained by a slowing of articulatory movements. In contrast, the voice onset time (VOT) values and the variation coefficients of the segments considered were not consistently increased. With respect to interarticulatory coordination, thus, a specific timing deficit could not be disclosed in FA dysarthria. These results are discrepant to data obtained with syllable repetition tasks, as reported in the literature. Obviously, the motor control of sentence utterances differs from that of syllable repetitions. There is psycholinguistic evidence that the complex movement patterns underlying sentence utterances are controlled by a single articulatory plan. The cerebellum, therefore, might not be a prerequisite for the initiation of articulatory gestures within the framework of sentence utterances.