An intracranial artery dissection has been recognized as a proper and definite clinical entity associated with subarachnoid hemorrhage (SAH), but true clinicopathological features of this disease have not been adequately elucidated. In this study, we investigated the pathological features ith angiographic correlates of 10 autopsied cases of an intracranial artery dissecting aneurysm and related lesions with SAH, including a case of dorsal wall aneurysm of the internal carotid artery or unknown-origin SAH.
Pathological study revealed that all 10 patients had a ruptured site on the lateral wall of the basal artery, and these lesions were classified into the following 3 categories: 1) fusiform dilatation, 2) lateral protrusion, 3) no dilatation. Three lesions of “fusiform dilatation” formed anenlarged aneurysm with false lumen and were thought to be a typical dissecting aneurysm. Four lesions of “lateral protrusion,” including ICA dorsal aneurysm, had no false lumen and formed a pseudoaneurysm at the arterial wall not related to the arterial divisions. Three other lesions of “no dilatation” were clinically diagnosed as SAH of unknown origin, although angiographic finding of diffuse narrowing was oberved at the ruptured site. Intra-wall dissecting hemorrhage without luminal connection was histopathologically identified as an origin of SAH.
Some characteristic information revealed in the previous reports was included in this classification, and good correlation between the pathological features and angiographic findings was seen. We conclude that this classification should be useful in discussions of the various clinicopathological subjects of the intracranial artery dissection.