De novo formation and rupture of an azygos pericallosal artery aneurysm. Case report.

An azygos pericallosal artery (APCA) aneurysm is a rare anomaly that is closely associated with saccular aneurysms. This is the earliest report to document de novo formation and rupture of an aneurysm at the bifurcation of an unpaired pericallosal trunk. The authors report the case of a woman who presented at the age of 52 years with subarachnoid hemorrhage (SAH) from the rupture of a newly formed APCA bifurcation aneurysm, 7 years after she had undergone surgery to clip a ruptured anterior cerebral artery aneurysm. De novo formation of aneurysms after SAH rarely occurs and certain risk factors like multiple and familial aneurysms, arterial hypertension, or smoking have been postulated. Late follow-up examination with angiography to detect de novo aneurysms should be considered in patients with this vascular anomaly after SAH.