[Postoperative hemorrhage due to normal pressure hyperperfusion breakthrough after a trapping of VA-PICA dissecting aneurysm].

We described a case of cerebellar hemorrhage after trapping of a vertebral artery dissecting aneurysm. A forty-eight-year-old man had suffered from severe headache, vomiting and disturbance of consciousness. He was transferred to our hospital in an ambulance. Emergency CT scan showed subarachnoid hemorrhage in the posterior fossa predominantly, intraventricular hemorrhage and hydrocephalus change. Chest X-ray showed radiological evidence of pulmonary edema. The initial blood-gas determinations demonstrated a marked reduction in PaO2 and increased PaCO2. Five days after admission, the patient's condition was improving. Cerebral angiography was performed using the Seldinger method. It revealed a right vertebral artery dissecting aneurysm just distal to the posterior inferior cerebellar artery. We performed an operation to trap the VA dissecting aneurysm. Blood pressure was well controlled under 140 mmHg during the operation and he recovered from anesthesia completely. On the day after the operation, suddenly the patient's consciousness began to deteriorate. Emergency CT scan was performed and it showed SAH, cerebellar hemorrhage and diffuse swelling of the cerebellum on the same side as the operation. We suspected rebleeding of the aneurysm due to a clip's having slipped. Reoperation was performed, but the clip was not displaced and there were no definite bleeding vessels on the operative field. Consequently only external decompression and resection of the right cerebellum were performed. We discuss pathogenesis of the occurrence of hemorrhage in this particular case after trapping. We also review the relevant literature.