Cerebral aneurysms associated with fenestration of the cerebral arteries: Three case reports and review of the literature

Fenestration of the cerebral artery is a rare anomaly often associated with saccular aneurysms. We here report 3 operated cases showing the aneurysmal formation at the fenestration of the anterior or middle cerebral arteries. 3D angiography was useful to delineate the aneurysm and the fenestrated vessels as compared with conventional angiography. In the first case demonstrating an aneurysm at the M1 (middle cerebral artery, postorbital portion) fenestration, neck clipping was completed preserving the perforators after dissecting the aneurysmal sac from the fenestrated vessel. In other two cases presenting aneurysms at the A1 (anterior cerebral artery, supraoptic portion) fenestration, neck clipping was also attempted. However, since the fenestrated vessels adhered to the aneurysmal dome, minor vessel of the fenestration was clipped with aneurysmal neck, or the fenestration was trapped including the aneurysm. Complete neck clipping is ideal for the aneurysm at the fenestration. However, when the fenestrated vessels firmly adhere to the aneurysmal sac, it is an alternative strategy sacrificing the minor vessel of the fenestration or trapping of the fenestration with aneurysm if cerebral blood flow is assured not to be compromised.