One-stage combined open and endovascular treatment using a hybrid operating room is safe and effective for distal middle cerebral artery aneurysms.

Background Aneurysms located in the distal middle cerebral artery (MCA) are relatively rare and lack an established treatment strategy. For distal MCA (DMCA) aneurysms, we performed a one-stage combined procedure of endovascular parent artery occlusion (PAO) with coils and superficial temporal artery to middle cerebral artery (STA-MCA) bypass in a hybrid operating room (HOR). The aim of this study was to evaluate the safety and efficacy of this procedure. Methods Cases of unruptured DMCA aneurysms treated with the one-stage combined PAO and STA-MCA bypass in HOR were retrospectively examined, and patients’ and aneurysmal backgrounds, surgical procedures, and treatment outcomes were analyzed. Results Six patients were included in the study. The average maximum diameter of the aneurysms was 14.4 mm. One aneurysm was located at M2 and five at M3. All aneurysms had a fusiform shape. No cases were associated with infection, trauma, or malignant tumors. In all six cases, the combined PAO and STA-MCA bypass was successfully completed. No postoperative hemorrhagic complications occurred. A symptomatic ischemic complication occurred in one case whose symptom disappeared in a week. Three months after surgery, complete obliteration of the aneurysm and patency of the bypass were confirmed in all cases. Conclusions The one-stage combined PAO and STA-MCA bypass in the HOR is safe and effective for DMCA aneurysms, potentially serving as a treatment option for this complex aneurysm.