Balancing Time and Risk: Temporary Arterial Occlusion in Middle Cerebral Artery Aneurysm Surgery

Background: Temporary arterial occlusion (TAO) is a key adjunct in microsurgical clipping of middle cerebral artery (MCA) aneurysms, but its safe duration and impact on perioperative ischemia-particularly in subarachnoid hemorrhage (SAH)-remain uncertain. Methods: A retrospective cohort of 245 patients undergoing microsurgical clipping of MCA aneurysms (154 incidental, 91 SAH) at a tertiary neurovascular center (2010-2020) was analyzed. TAO use, cumulative duration (>5, >8, >10, >15 min), number of applications, and occlusion site were extracted alongside clinical, radiographic, and outcome data. The primary endpoint was perioperative ischemia within 48 h; secondary endpoints included clinically relevant cerebral vasospasm (CVS), intraoperative rupture, and functional outcome (mRS) at discharge and 6 months. Multivariable logistic and ordinal regression models adjusted for demographic, aneurysmal, and treatment covariates. Results: TAO was used in 134 cases (54.7%; mean total duration 10.4 ± 8.7 min). In the overall cohort, TAO (presence or duration) was not independently associated with perioperative ischemia or CVS. In the SAH subgroup, cumulative TAO > 5 min conferred an approximately sixfold higher odds of ischemia (p = 0.012; OR 6.33), whereas no threshold was significant in incidental aneurysms. Female sex, M2 location, SAH at admission, and initial GCS < 9 independently predicted ischemia; female sex, higher ASA grade, larger size, irregular morphology, and SAH predicted CVS. SAH and aneurysm wall calcification were associated with worse 6-month mRS. Conclusions: TAO appears safe in elective clipping of incidental MCA aneurysms when applied judiciously, but cumulative durations beyond 5 min substantially increase ischemia risk in SAH patients. TAO management should therefore be individualized by rupture status, neurological grade, and aneurysm morphology rather than a single universal time limit.