Fenestrations of intracranial arteries.

BACKGROUND AND PURPOSE Few data are available on the frequency and location distribution of fenestrations of intracranial arteries. We used 3D rotational angiography of all intracranial arteries in a cohort of 179 patients with suspected intracranial aneurysms to assess the prevalence and location of fenestrations and the relation of fenestrations to aneurysms. MATERIALS AND METHODS Of 179 patients with subarachnoid hemorrhage admitted between March 2013 and June 2014, 140 had 3D rotational angiography of all cerebral vessels. The presence and location of aneurysms and fenestrations were assessed. In patients with both aneurysms and fenestrations, we classified the relation of the location of the aneurysm as remote from the fenestration or on the fenestration. RESULTS In 140 patients, 210 aneurysms were present. In 33 of 140 patients (24%; 95% confidence interval, 17.2%-31.3%), 45 fenestrations were detected with the following locations: anterior communicating artery in 31 (69%), A1 segment of the anterior cerebral artery in 4 (9%), middle cerebral artery in 4 (9%), basilar artery in 4 (9%), vertebral artery in 1 (2%), and anterior inferior cerebellar artery in 1 (2%). Of 56 patients with anterior communicating artery aneurysms, 14 had a fenestration on the anterior communicating artery complex. The remaining 31 fenestrations had no anatomic relation to aneurysms. In 140 patients with 210 aneurysms, 14 aneurysms (7%) were located on a fenestration and 196 were not. CONCLUSIONS In patients with a suspected ruptured aneurysm, fenestrations of intracranial arteries were detected in 24% (33 of 140). Most fenestrations were located on the anterior communicating artery. Of 45 fenestrations, 14 (31%) were related to an aneurysm.