[Middle Cerebral Artery Fenestration with M2 Fusion Detected during Aneurysm Clipping:A Case Report]

We report a unique case of middle cerebral artery fenestration with M2 fusion detected during an aneurysm clipping. A 72-year-old woman was diagnosed with an unruptured aneurysm of the right middle cerebral artery, and middle cerebral artery fenestration with M2 fusion was detected during the aneurysm clipping surgery. It was difficult to identify this unusual vascular anomaly before the surgery. Therefore, neurosurgeons should be cautious of such hidden vascular anomalies and be prepared for the possible complications during surgery.