[Some consideration about cerebellar ataxia and crossed cerebellar diaschisis in Dejerine-Roussy syndrome].

We report a 68-year-old right-handed male who exhibited Dejerine-Roussy syndrome including a persistent cerebellar ataxia following the left thalamic hemorrhage with special reference to the evolution of crossed cerebellar diaschisis (CCD) measured with positron emission tomography (PET). The initial PET studies performed 50 days after onset revealed a mild reduction of blood flow and glucose metabolism in the right cerebellar hemisphere in addition to the severe reduction in the left thalamus. Even in the chronic stage when the motor weakness almost disappeared, he persistently showed a cerebellar ataxia in his right extremities. The cerebellar blood flow and metabolism became normalized without laterality in the follow-up PET studies which were performed 29 months after onset, although the left thalamus and left cerebral cortices were still severely involved. The cerebellar ataxia with preserved cerebellar blood flow and metabolism following the thalamic hemorrhage was possibly associated with damage to the efferent fibers from the cerebellum, whereas the CCD observed in the early stage probably was caused by a transient involvement of the cortico-ponto-cerebellar tract at the level of the internal capsule.