Intraoperative ultrasound for localization of a ruptured M2-M3 middle cerebral artery aneurysm with temporal hematoma: A case report.

We present a patient who had a ruptured distal middle cerebral artery (MCA) aneurysm at the M2-M3 junction with a temporal lobe hematoma, in which intraoperative ultrasound (iUS) proved critical for real-time aneurysm localization when neuronavigation was compromised by brain shift. An elderly patient with subarachnoid hemorrhage and a large temporal lobe intracerebral hematoma underwent craniotomy, hematoma evacuation, and aneurysm clipping. Preoperative computed tomography angiography (CTA) identified a 5-mm aneurysm at the left M2-M3 junction. During surgery, neuronavigation was initially planned but deemed unreliable after hematoma removal due to brain shift. Instead, iUS was used through the cortical surface to localize the aneurysm and parent vessels in real-time. iUS successfully visualized the aneurysmal sac and inflow vessel within the evacuated hematoma cavity. This allowed the surgical team to safely expose the parent vessel, identify the aneurysm neck, and clip the aneurysm without complications. Postoperative imaging confirmed complete hematoma evacuation and aneurysm obliteration. In patients with deep-seated ruptured distal MCA aneurysm accompanied by intracerebral hematoma, iUS can be a valuable real-time tool for localization when neuronavigation is unreliable, thereby improving surgical precision and safety.