Left-hemispheric dominance for articulation: a prospective study on acute ischaemic dysarthria at different localizations.
Twelve patients with cerebellar infarction, 8 in the region supplied by the posterior inferior cerebellar artery (PICA) and 4 in the territory of the superior cerebellar artery, underwent formal perceptual examination for speech deficits. With respect to topography the results firstly underline the significance of the paravermal region of the superior cerebellar portion for speech functions. In all patients with dysarthric impairment the lesion extended to this area, whereas patients with PICA infarction sparing the superior portion of the cerebellum showed no speech deficits. Secondly the findings do not corroborate the notion of an exclusively left-sided cerebellar speech motor control, since 3 of the 4 dysarthric subjects had unilateral right-sided ischaemia. This study thirdly demonstrates that lesions of the cerebellar cortex without involvement of the dentate nucleus can cause dysarthric impairment. Phonetic analysis revealed irregularly distributed articulatory deficits and slowed speech tempo as the most common dysarthric features.