Cerebellar haemorrhage after supratentorial aneurysm surgery with lumbar drainage.

Haemorrhage within the posterior fossa (PF) after supratentorial surgery is a very rare and exceedingly dangerous complication. Only 28 cases were found in the literature. Up to now, no pathogenetic factor has decisively proven to be the cause of this phenomenon. We present clinical details of a patient operated on for aneurysm of the anterior communicating artery. Lumbar drainage was used during surgery, with the loss of a large amount of cerebrospinal fluid (200 ml). Other causes in our case which may have led to cerebellar shift or a critical increase in transmural venous pressure with subsequent vascular disruption and haemorrhage were extreme head rotation during lengthy surgery and blood pressure peaks in the early postoperative period. Repeated computed tomography (CT) allowed immediate diagnosis of this complication and control of its conservative management. After postponed ventriculoperitoneal shunt, the patient recovered completely.