Supratentorial intracerebral hemorrhage after posterior fossa operation.

Three cases of supratentorial intracerebral hemorrhage after posterior fossa operation are described, and nine other cases reported in the literature are reviewed. The possible causes are discussed, but in eight cases no definite cause could be found. All eight patients were operated on in the sitting position, and all had hematomas in the subcortical white matter. A possible cause might be changes in intracranial dynamics in the sitting position with disruption of subcortical veins. Other authors mention the possibility of occlusion of carotid or vertebral vessels in the neck by improper positioning of the head leading to intraoperative infarction and to hemorrhage within the infarcted brain after repositioning of the patient. With the patient in a lateral or semilateral position, this complication should be preventable.