Non-aneurysmal subarachnoid hemorrhage associated with basilar artery dissection--autopsy case report.

A 60-year-old male presented with subarachnoid hemorrhage (SAH) of unknown origin and died of peritonitis 2 months after the ictus. Computed tomography on admission revealed localized hemorrhage at the interpedunclar cistern and sedimentation in both posterior horns. Repeat angiography could not detect any aneurysm. Postmortem histological examination revealed disruption of the wall associated with intramural hemorrhage at the top of the basilar artery, and subintimal hemorrhages of the lower basilar artery and the left vertebral artery. Arterial dissection of the vertebrobasilar system may be a cause of SAH of unknown origin including perimesencephalic hemorrhage.