Healing process for cerebral dissecting aneurysms presenting with subarachnoid hemorrhage.

Abstract

This was a pathological study to investigate the healing process for cerebral dissecting aneurysms presenting with subarachnoid hemorrhage (SAH). Thirteen dissecting aneurysms that presented with SAH were obtained from 13 patients. Nine aneurysms arose from the vertebral artery, two arose from the anterior cerebral artery, one arose from the internal carotid artery, and one arose from the superior cerebellar artery. Eight aneurysm specimens were collected during autopsy and five were resected during surgery (trapping with or without bypass). The period between the onset of SAH and the time of specimen collection ranged from 6 hours to 35 days. All 13 aneurysms were pathologically examined with immunohistochemical staining, with a focus on the chronological healing process after SAH. All dissecting aneurysms were generated with sudden widespread disruption of the internal elastic lamina and media. The healing process occurred with neointimal proliferation. The neointima, consisting mainly of newly synthesized smooth muscle cells and collagen fibers, extended from the disrupted ends of the media proper forward to the ruptured portion. It is assumed that the healing process, with neointimal proliferation, begins after 1 week and may not be complete even after 1 month, depending on the extent of the wall injury.