Cerebral diaschisis in patients with malignant glioma.

A positron emission tomography study using [18F]-fluorodeoxyglucose was undertaken to identify and quantitate whether diaschisis occurred in cerebral cortex, basal ganglia, or thalamus, as well as in cerebellar cortex and dentate nuclei in patients with malignant glioma. The relationship between diaschisis in these cerebral structures and clinically significant hemiparesis in patients was analysed. A 30% decrease in the regional metabolic rate for glucose in the cerebellar hemisphere contralateral to the tumor, and ipsilateral to the motor deficit, was identified and was statistically significant (p greater than 0.001). Decreased metabolism in the cerebellar hemisphere contralateral to the tumor was not seen in patients without hemiparesis. Parietal lobes affected by tumor had a larger decrease in metabolism than did frontal lobes with tumor (p greater than 0.01). The overall metabolism of the unaffected cerebellar hemisphere, relative to the peak metabolic activity of the brain, was not depressed in patients with tumor. In addition, the activity of subcortical nuclei was relatively unaffected by adjacent tumor or motor deficit.