Glucose metabolism in the human cerebellum: an analysis of crossed cerebellar diaschisis in children with unilateral cerebral injury.

Using high-resolution positron emission tomography (PET), we have recently described the normal pattern of glucose utilization in 11 anatomical regions of the human cerebellum. In the present study, we evaluated the phenomenon of crossed cerebellar diaschisis in 40 patients (mostly children) with unilateral cerebral injury sustained at various periods of brain development. Diaschisis refers to a functional impairment at a remote site following injury to an anatomically connected area of brain and, presumably due to a loss of afferent input to the remote site. Of the 40 patients, 11 had sustained their cerebral injury prenatally, 7 in the perinatal period (+/- 24 hours of birth), and 22 postnatally (1 day to 15 years). Crossed cerebellar hypometabolism was seen in 22 patients; symmetric cerebellar metabolism was found in 16 subjects. The presence of crossed cerebellar hypometabolism was typically associated (75% of cases) with a postnatal injury, while symmetric cerebellar metabolism was seen only in patients with injury occurring prior to 4 weeks of age (13 of the 16 had prenatal or perinatal insults). A third pattern of cerebellar metabolism, consisting of paradoxical crossed cerebellar hypermetabolism, was seen in two patients; both had sustained their cerebral injury at 4 months of age. These findings suggest the presence of considerable plasticity, which is dependent on age at injury, in the cerebrocerebellar pathway of developing brain.