A 58-year-old male presented with severe consciousness disturbance and left hemiparesis. Computed tomography (CT) revealed subarachnoid hemorrhage (SAH) and acute subdural hematoma caused by a ruptured right middle cerebral artery aneurysm. The aneurysm was clipped and the hematoma was evacuated. The patient had almost recovered without new neurological deficits on the next day. Arterial systolic blood pressure was postoperatively controlled within 120 to 150 mmHg. Continuous ventricular and cisternal drainage from the level 10 cm above the external auditory meatus was performed to drain bloody cerebrospinal fluid and prevent vasospasm. Three days after surgery, the patient suddenly lapsed into a coma. CT demonstrated diffuse SAH and bilateral intraventricular hemorrhage caused by rupture of an anterior communicating artery aneurysm. Neck clipping was performed immediately. Unfortunately, the patient died of primary damage due to SAH 3 days after the second surgery. In this case, cisternal drainage was probably important in the aneurysm rupture because of decreased intracranial pressure and change in the perianeurysm environment. Postoperative management of patients with residual untreated aneurysms must consider the possibility that cisternal drainage may result in higher transmural pressure, leading to rupture of the untreated aneurysms.
