Cerebellar blood flow and metabolism in cerebral hemisphere infarction.

Positron emission tomography was used to study the effect of supratentorial infarction on cerebellar metabolic rate for oxygen and cerebellar blood flow. In a control group of patients, the mean cerebellar metabolic rate for oxygen was 2.97 +/- 0.11 (standard error of the mean [SEM] ) ml-1 . min-1 . hg-1 and mean cerebellar blood flow was 41.1 +/- 1.5 ml . min-1 . hg-1. No significant right-left asymmetry in either cerebellar metabolic rate for oxygen or cerebellar blood flow was noted. Patients with frontal lobe infarction showed 16.8 +/- 1.8% (cerebellar metabolic rate for oxygen) and 19.6 +/- 2.1% (cerebellar blood flow) differences between cerebellar hemispheres, with the hemisphere contralateral to the cerebral infarction having the lower values. These differences were highly significant (p less than 0.001). In addition, cerebellar blood flow and cerebellar metabolic rate for oxygen were significantly decreased in the ipsilateral cerebellar hemisphere (metabolism: 2.13 +/- 0.19 ml . min-1 . hg-1; p less than 0.002; blood flow: 35.2 +/- 2.4 ml . min-1 . hg-1; p less than 0.05). Patients with parietooccipital infarction also showed a significant bilateral decrease in cerebellar metabolic rate for oxygen (2.43 +/- 0.11 ml . min-1 . hg-1) and cerebellar blood flow (34.6 +/- 2.5 ml . min-1 . hg-1) relative to control subjects, but no significant cerebellar asymmetry. Our findings demonstrate a general depression of cerebellar blood flow and metabolism from cerebral hemisphere infarction unrelated to the site of infarction as well as a specific depression occurring contralateral to infarction involving the frontal lobe. These are among the first quantitative data concerning regional cerebellar metabolic rates for oxygen and cerebellar blood flow in humans.