Unilateral double fenestration of the same posterior cerebral artery at P1 segment: first cadaveric case report and literature review

Purpose: Arterial fenestration involves an artery emerging from the same embryological origin, with its lumen divided into two channels that subsequently rejoin. This kind of vascular variant has consequences, such as focal defects in the histologic layers of the arteries, hemodynamic stress, and challenges for endovascular procedures in the management of vascular pathologies. The main objective of this work is to present a rare vascular variant, a double fenestration of the same P1 segment of a cadaveric specimen, and a literature review of these kind of vascular variants. Methods: A cadaveric study was performed in which 20 central nervous system specimens, from patients without neurological pathology obtained as a donation from the National Institute of Legal Medicine and Forensic Sciences, were dissected for educational and research purposes. Results: In one specimen it was found a double fenestration of the right P1 segment, associated with a single fenestration of the right superior cerebellar artery. Few cases of posterior circulation fenestration, beyond the vertebrobasilar trunk are reported in the literature, with limited understanding of the potential hemodynamic consequences thereof. In all the literature available, only eight cadaveric cases of P1 segment fenestration are documented, often linked with other central nervous system vascular abnormalities such as aneurysms or duplications. Conclusions: There is a single report of unilateral double P1 segment fenestration in a living patient. To our knowledge, this is the second case reported in the literature on this specific anatomical anomaly, and the first such report in a cadaver.