True Posterior Communicating Artery Dissecting Aneurysm Treated with Primary Coiling Complicated By PCA-Territory Infarction and Homonymous Hemianopia

Background: Cerebral aneurysms can be tedious and complicated to treat, given their unpredictable nature and potentially harmful outcomes. True PCoA dissecting aneurysms, specifically, are rare. Coiling is used to treat intracranial aneurysms by isolating the aneurysmal sac from active circulation using detachable coils, therefore blocking blood flow to the aneurysm. Even though it is a common technique, it carries risks of distal embolization and branch/perforator compromise. Case Description: A 37-year-old female presented with Fisher scale 2 basal subarachnoid hemorrhage. Angiography showed a true posterior communicating artery dissecting aneurysm. She underwent primary coiling under intraprocedural anticoagulation and periprocedural antiplatelet therapy. Early postoperative MRI demonstrated an acute left PCA-territory infarction on DWI/ADC, and examination revealed right homonymous hemianopia. She was discharged with GCS 15 and persistent visual field deficit. Conclusion: PCA-territory infarction may complicate coiling of true PCoA dissecting aneurysms despite parent vessel patency preservation. Likely mechanisms include thromboembolism during coil deployment and compromise of PCoA-PCA perforators or fetal-type flow configurations. Although the patient was receiving both AC and AP therapies, the ischemia developed with no obvious parent vessel occlusion in the visual cortex. Learning Points: • Ischemic complications can occur despite anticoagulation/antiplatelet therapy and apparent parent vessel patency. • Variant PCoA/PCA anatomy can increase ischemic risk and should inform strategy. • In addition to AC and AP therapies, more measures may be necessary to prevent adverse outcomes in aneurysm treatment with dissection and coiling • Immediate post-treatment MRI helps correlate angiographic result with neurological outcome. • Additional research needs to be done to clarify the mechanisms behind the infarction during coiling Publication History Article published online: 27 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany