MR imaging quantification of cerebellar growth following hypoxic-ischemic injury to the neonatal brain.

BACKGROUND AND PURPOSE Cerebellar atrophy may occur as a result of a primary injury, such as infarction or hemorrhage. Impaired growth of a non-injured cerebellum may be seen as a secondary effect related to damage in other remote but connected areas of the brain, or so-called diaschisis. We sought to determine whether perinatal hypoxic-ischemic injury leads to poor cerebellar growth and whether such impairment occurs asymmetrically in infants with predominantly unilateral brain injury. METHODS We used a computerized quantification program to measure cerebellar size by using serial MR images. Term-born infants presenting with encephalopathy and/or seizures presumed due to a hypoxic-ischemic insult within 48 hours of delivery were included if they had two or more volume acquisition images obtained at least 3 months apart but within the first 15 months of delivery. RESULTS When data were grouped by MR appearances, significant differences in total cerebellum growth were seen between infants with focal infarction and those with basal ganglia and thalamic injury (P <.001). Unilateral forebrain lesions shown on MR imaging were not predictive of asymmetric cerebellar growth. CONCLUSION Infants with focal infarction of the cerebral hemisphere had an apparently normal pattern of growth in both cerebellar hemispheres. However, in infants with severe basal ganglia and thalamic lesions, cerebellar growth was reduced, and the vermis showed little or no growth during the first year after birth.