Abstract
A 64-year-old woman presented with dissecting aneurysm of the anterior cerebral artery (ACA) manifesting as subarachnoid hemorrhage (SAH). On a computerized tomographic scan (CTA) a saccular aneurysm was absent, but there was a finding of dilatation of the left proximal segment of ACA (A1). The patient underwent a left craniotomy. Intraoperative observation revealed that the vessel wall of the left A1 was dark purple, a typical finding of dissecting aneurysm.
With increasing frequency, dissecting aneurysms of the intracranial arteries are recognized as a possible cause of SAH. In a majority of cases of intracranial dissecting aneurysms, the aneurysm afflicted the vertebral and basilar arteries.
It is relatively rare for this type of aneurysm to be confined to the anterior cerebral artery. In the literature, 19 cases of dissecting aneurysm in A1 segment were reported including our case. Majority cases of dissecting aneurysm in A1 segment eventually ruptured, resulting in SAH.
In the case of SAH of unknown origin, dissecting aneurysm should always be kept in mind even if the angiogram does not show any abnormal findings.
