Thrombotic, Dolichoectatic, Distal Posterior Cerebral Artery Aneurysm Treated with Excision and P2-P2 Reanastomosis

Posterior cerebral artery aneurysms are rare and often optimally treated with clip reconstruction.^1-3 Complex cases may require aneurysm excision with in situ reanastomosis.^4-6 A woman in her early 40s presented with 2 weeks of severe headache and received a diagnosis of a thrombotic, dolichoectatic, distal right P2 aneurysm. Clip reconstruction was recommended. After providing consent, the patient underwent a right subtemporal approach. The P2 aneurysm was encountered in the ambient cistern. The aneurysm and its inflow and outflow arteries were isolated, and bleeding was controlled with temporary clips. Primary clip reconstruction was aborted due to a neck configuration that precluded preservation of the outflow vessels during primary clip reconstruction. The decision was made to excise the aneurysm and perform a P2-P2 end-to-end reanastomosis.⁷ After completion of the initial bypass, indocyanine green videoangiography indicated bypass thrombosis, which was thought to be attributable to poor tissue quality from inadequate vessel trimming at the anastomosis site. We elected to excise the bypass, trim both P2 ends back to healthy tissue, and perform a repeat end-to-end P2-P2 reanastomosis, which ultimately resulted in successful revascularization with indocyanine green confirmation. Postoperative angiography confirmed complete obliteration of the aneurysm with stable graft patency, and the patient remained intact at her neurologic baseline through last follow-up at 6 weeks after discharge from the hospital. Video 1 demonstrates microsurgical nuances for deep end-to-end reanastomosis, as well as intraoperative troubleshooting in the setting of a complex ruptured posterior circulation aneurysm.