Disruption of Cerebellar Development: Potential Complication of Extreme Prematurity

BACKGROUND AND PURPOSE: Infants with very low birth weight are at high risk for cerebral lesions. Although supratentorial brain damage is a common radiologic finding, pos-terior fossa pathologies are rare. We studied the morphology of cerebellar involvement in a large series of 28 premature infants born before the 30th week of gestation to define typical patterns and identify possible risk factors for this pathology. METHODS: Cranial sonograms were obtained in the early neonatal period. MR imaging was performed between the 2nd month and the 6th year of life. Morphologic patterns of cerebellar involvement were evaluated. RESULTS: Three morphologic patterns of cerebellar involvement were recognized: (1) sym-metric volume reduction of the cerebellar hemispheres, which were floating immediately beneath the tentorium, and a small vermis with preserved shape; (2) symmetrical reduction in hemispheric volume with an enlarged, balloon-shaped fourth ventricle and a small, deformed vermis; and (3) normal overall cerebellar shape with extensive reduction of its dimensions. A small brain stem with flattened anterior curvature of the pons and loss of supratentorial white matter was present in all patients