Cerebellar induced aphasia: case report of cerebellar induced prefrontal aphasic language phenomena supported by SPECT findings.

A 73-year-old right-handed man with ischemic infarction in the vascular territory of the right arteria cerebellaris superior is described. In the acute phase he presented with cerebellar and brainstem symptoms, followed within a few days by a paresis of the right arm and unexpected language disturbances of aphasic origin. The core features of the aphasic syndrome corresponded to a diagnosis of Luria's dynamic aphasia, complicated by expressive and receptive agrammatism. During one year follow-up the ataxia and paretic symptoms disappeared but the slightly ameliorated aphasic syndrome and the sensory disturbances in the left hemicorpus persisted. In the absence of any neuroradiological evidence for a structural lesion in the left frontal language areas, the hypothetical causative role of the right cerebellar lesion on the contralateral prefrontal aphasic symptomatology is advocated and supported by positive 99mTc-hexamethylpropyleneamine oxime single-photon emission-computed tomography findings, revealing a focal hypoperfusion in the clinically suspected areas. In our case, this phenomenon of so-called 'crossed cerebello-cerebral diaschisis', reflecting the distant functional impact of the right cerebellum on the contralateral prefrontal cortical areas, is for the first time associated with an aphasiologic substrate. The co-occurrence of a right cerebellar lesion and an aphasic syndrome forms the first clinical illustration of the pathophysiological hypothesis of a deactivation of prefrontal left hemisphere language functions due to the loss of excitatory impulses through cerebello-ponto-thalamo-cortical pathways.