E-196 The risk of ischemia in preventive temporary artery occlusion of the contralateral anterior cerebral artery during microsurgical clipping of ACOM aneurysms

Introduction Temporary artery occlusion (TAO) is commonly used to facilitate dissection and clipping of intracranial aneurysms. When clipping anterior communicating artery (Acom) aneurysms, a possible strategy is to perform early preventive TAO of the contralateral A1 segment of the anterior cerebral artery before dissecting towards the aneurysm. In case of intraoperative complications such as complicated aneurysm dome preparation or inadvertent rupture of the aneurysm, full proximal control can be quickly gained by additional TAO of the easily accessible ipsilateral A1. Also, right-sided approaches are sometimes preferred due to reduced risk of damage of the dominant hemisphere and right-handedness of the surgeon. However, this may lead to prolonged TAO times of the contralateral A1 and might involve the risk of cerebral ischemia, especially if the contralateral A1 is the dominant supplier. In the present study, we aimed to investigate the safety of this strategy. Methods We retrospectively analyzed the clinical and imaging outcomes of Acom aneurysms treated at our institution over a period of seven years by a right-sided frontotemporal approach. Temporary contralateral A1 occlusion early after opening of the chiasmatic cistern was defined as early TAO. We evaluated the total TAO time, A1 dominance, intraoperative rupture rates as well as postoperative mRS. The primary outcome parameter was postoperative ischemia determined on CT scans within 48 hours after surgery by a board-certified neuroradiologist. Results A total of 81 including 52 ruptured and 29 unruptured aneurysms were treated by microsurgical clipping over a period of seven years. In 48 patients (59%) early contralateral A1 TAO was performed for an average of 22±20 min and the majority of these cases (30 patients) harbored a dominant contralateral A1. Bilateral TAO was performed in 22 patients (27%) for 11±10 min. Intraoperative rupture occurred in 20 patients (25%) of which 10 received early TAO. Postoperatively, 5 patients showed postoperative ischemia (6%). Bilateral TAO as well as dominant early TAO showed no significant correlation with ischemia or worse post-operative mRS. However, patients with ischemia had a significantly longer overall TAO time (45±27 mins) than patients without (19±18 mins) (p=0.02). Conclusion In our patient population neither early TAO of the dominant A1 nor bilateral TAO appeared to have an increased risk for ischemia. However, prolonged TAO, regardless of which side should be avoided. Disclosures C. Wipplinger: None. F. Mrosk: None. S. Tulu: None. C. Preuss-Hernandez: None. W. Ho: None. A. Gorke: None. M. Ortler: None. O. Petr: None. C. Thome: None.