A Case of Hybrid Surgery for Dissection of the Posterior Cerebral Artery P1-P2 Segment Presenting with Subarachnoid Hemorrhage

Abstract

Proximal posterior cerebral artery (PCA) fusiform aneurysms are challenging to treat due to their deep-seated location and the need to maintain distal blood flow whilst preserving the perforating branches. In this case, a subarachnoid hemorrhage occurred due to fusiform dissection of PCA P1-P2 segments, with the dissection involving the posterior communicating artery (Pcom) and perforating branches. The posterior thalamoperforating artery originated from the contralateral PCA P1 segment. On the day of onset, evaluation of collateral circulation through balloon occlusion testing at the terminal portion of the basal artery was attempted, but precise assessment of collateral circulation due to occlusion of the dissected portion was not possible, because temporary occlusion of the right Pcom could not be achieved. Stent-assisted coil embolization was performed on the same day, but recurred on the 19th day of illness. On the 25th day, superficial temporal artery to PCA P2 bypass surgery was performed, followed by endovascular treatment for aneurysmal occlusion and proximal occlusion on the 27th day. However, the patient developed a midbrain-thalamic infarction due to the occlusion of the long circumflex branch at the dissection site. After 1 year and 6 months, the patient had residual mild hemiparesis and ocular movement disorder but achieved social reintegration. Treatment of PCA P1-P2 segment dissection remains challenging both surgically and endovascularly due to the need to occlude the dissected portion while preserving collateral circulation and perforating branches, necessitating individualized treatment decisions.