Contralateral cerebellar hypometabolism: a predictor for stroke outcome?

Contralateral cerebellar hypometabolism (CCH) is a well established remote functional effect of cerebral damage. Because CCH has been reported to be reversible in acute stroke in at least some patients, the value of cerebellar metabolic asymmetry (CbMA; a reflection of the degree of CCH) as a predictor of stroke outcome has been assessed. Measurements of cerebellar oxygen consumption were performed by positron emission tomography (PET) in 16 patients within 5-30 hours of onset of their first ever middle cerebral artery territory stroke, and again 13-56 days later in 12 survivors. The neurological state was quantified at the time of each PET study and at day 60, with both the Mathew and Orgogozo scales. In the early PET study, the CbMAs ranged from around 0% to nearly 50% (individually significant at p < 0.05 in 9/16 patients) but were neither strongly nor consistently correlated with neurological outcome or recovery at day 60. Similarly, the changes in CbMAs from the early to the late PET study were not correlated with the concomitant neurological evolution. At the late PET study, however, there were excellent positive correlations between CbMAs and both neurological status and size of infarction (assessed by CT in the chronic stage). The correlation with neurological status was explained by the correlation with size of infarction. The poor predictive value of CbMAs in the early PET study may be partly because the cerebral metabolic disturbance might still be evolving at this early stage in some cases. Despite this lack of a strong quantitative link between CbMAs at the early PET study and outcome, the outcome was good in all the patients who did not exhibit significant CCH, suggesting that lack of CCH may predict good outcome in acute middle cerebral artery stroke.