Bilateral Premammillary Artery Territory Infarctions After Clipping of a Ruptured Internal Carotid-Posterior Communicating Artery Aneurysm: A Case Report.

Preservation of the posterior communicating artery and its perforators is critical during clipping of posterior communicating artery aneurysms. We report the case of a woman in her 70s who developed bilateral premammillary artery territory infarctions after microsurgical clipping of a ruptured right internal carotid-posterior communicating artery aneurysm. On admission, her Glasgow Coma Scale score was 15, and her World Federation of Neurosurgical Societies grade was I. Intraoperatively, clip replacement and repeated readjustment were required. Final microscopic inspection and Doppler ultrasonography confirmed preservation of flow in the posterior communicating artery and its perforators. Postoperatively, she developed impaired consciousness and left hemiparesis, and serial imaging demonstrated bilateral low-density lesions in the premammillary artery territories. Muscle strength improved with rehabilitation, and she was transferred on postoperative day 20. The notable feature of this case was the bilateral distribution of infarction. We considered that, in addition to ipsilateral perforator compromise, reduced flow through the circuminfundibular plexus may have contributed to contralateral ischemia. This case highlights that bilateral perforator territory infarctions may occur despite apparent intraoperative preservation of perforator flow.