A Case of Dissecting Posterior Communicating Artery Aneurysm That Was Difficult to Identify Preoperatively as the Source of Hemorrhage

Abstract

We report a case of a dissecting posterior communicating artery aneurysm that was difficult to identify preoperatively as the source of hemorrhage. A 69-year-old male was admitted to our hospital with the complaint of sudden onset of severe headache. Computed tomography angiography (CTA) demonstrated a 2-mm aneurysm at the bifurcation of the right middle cerebral artery (MCA). The hematoma was predominantly distributed on the right side on the CT scan. Cerebral angiography did not reveal any additional source of bleeding. The MCA aneurysm was therefore presumed to be ruptured, and surgical neck clipping was performed.

Intraoperatively, the right MCA aneurysm did not adhere to the surrounding hematoma. Further exploration during hematoma removal revealed a large hematoma around the internal carotid artery (IC) and a thin hematoma adhering to the red vascular wall of the posterior communicating artery (Pcom). Based on these findings, we concluded that the dissecting aneurysm at the Pcom had ruptured. As a penetrating branch was found at the dissection site, direct surgical intervention was deemed difficult, and aneurysm wrapping was performed instead. Postoperative MRI revealed no ischemic changes. The patient eventually recovered with a modified Rankin Scale score of 1. In this case, preoperative imaging failed to accurately identify the bleeding source, and a definitive diagnosis was achieved intraoperatively. The ability to identify the source of bleeding under a microscope is an advantage of craniotomy and is believed to have contributed to the favorable treatment outcomes in this case.