Contralateral cortical diaschisis in a patient with cerebellar astrocytoma after radiation therapy.

Contralateral cerebellar diaschisis, hypometabolism in the cerebellum contralateral to a cortical lesion, is a well described phenomenon in patients with stroke and brain tumor. However, few reports exist of patients with cerebellar lesions with the finding of contralateral cortical hypometabolism. The authors present a case of a patient with a right cerebellar astrocytoma after surgical resection and radiation therapy in which fluorine-18 fluorodeoxyglucose positron emission tomographic imaging, performed to rule out recurrent tumor, revealed global hypometabolism in the left cerebral cortex. The concept of contralateral cortical diaschisis and possible mechanisms and clinical implications are reviewed.