RESUMEN
We report two cases with delayed cerebellar hemorrhage developed after supratentorial burr-hole drainage, and review the literature. Burr-hole drainage was performed at both sides of bilateral chronic subdural hematomas. The total amount of drainage per day was more than 300ml of hematoma mixed with cerebrospinal fluid(CSF) and the differences in doses between the two sides were significant in both cases. The symptoms improved after drainage but abrupt deterioration of neurological status occurred with the development of cerebellar hemorrhage on postoperative day 4 and 5, in each case. Although both patients were elderly, 75 and 86 years old, they did not have any coagulation defect or episode of severe increase in their blood pressures during drainage. We believe that suprate-ntorial CSF overdrainage can cause cerebellar upward shift, with resultant injury of weakened cerebellar vessels in old age.