Duplicated posterior communicating artery affected by an aneurysm case report—possible developmental ground

Abstract Background Arterial fenestration and duplication is brain vascular developmental anomaly. Typically it is found in ACom, VA-BA, MCA segments. It may be accompanied by an aneurysm as a result of anatomy and factors forming vessel wall stress resistance. Such malformation is very rare in ICA locations, and almost no cases are described involving PCom. Presented case of double PCom with aneurysm puts an insight on possible fetal development of that ICA branch. Case presentation We present a case of a patient diagnosed with ICA and double PCom origin affected by an aneurysm. Patient was diagnosed due to history of migraine. DSA confirmed an aneurysm located on ventral side of C6ICA with accompanying two ICA branches that formed vascular structure, PCom with double origin. The patient underwent microvascular clipping with good results. Intraoperatively two vessels originating independently from ICA were recognized that merged on their further course and later formed PCom running to interpeduncular fossa. Similar, very rare lesions are recognized as ICA fenestration. They are formed due to failure to fuse in its developmental plexiform stage. In case of PCom development, much less detail is described in the literature. Paget stage one also shows stage with primitive flexiform PCom. It might stay multichannel after congenital period and be observed in the form of this malformation. Blood flow is changed in affected artery in two ways: by decreased vessel cross-sectional area and by increased wall stress in narrowed vessels. This stress load and increased blood flow speed may be additionally affected by unfavorable vessel angle. In result aneurysm formation in fenestrations, duplications can be observed. Conclusions ICA/PCom fenestration aneurysms can be treated effectively by microsurgical and endovascular methods. Because of changed vascular wall stress, patients diagnosed with arterial fenestrations might benefit from follow-up for aneurysm formation even if not detected initially.