2123 Novel Data on the Tolerance of the Basilar Artery for Temporary Occlusion: Potential Predictive Value of Loss of Consciousness During Awake Basilar Artery Temporary Occlusion

INTRODUCTION: The lack of an intra-operative neuromonitoring (IONM) modality for loss of consciousness (LOC) has historically limited our understanding of the impact of basilar artery (BA) temporary clipping (TC)/temporary hypoperfusion of midbrain/thalamic regions. METHODS: The OMTA study patients who underwent TC of specific intracranial vessels (n=320) provided the data points for this study. Each patient had 29 variables (demographic, clinical, radiologic, operative, and outcomes) recorded. Primary outcome variables were CVA, mRS, and Mortality. Sixty-one patients with BA aneurysms who underwent TC were identified. RESULTS: Within the total cohort (n=320), 222 patients underwent surgery under CS, and 98 under GA. Of the 61 patients with BA aneurysms who underwent TC, 39 (test group) were under CS, and 22 (control group) under GA. The test group had a lower risk of CVA (OR: 0.22, RR: 0.79) and lower chances of poor mRS scores. There was no statistical difference in the length of TC time between the two cohorts In the CS group, the 12 patients who experienced LOC during TC had statistically worse outcomes for CVA (RR = 1.28) and mRS (RR = 1.26) compared to those who did not. The mean time to LOC was 51 seconds after TC placement. CONCLUSIONS: Based on our findings, we theorize that there is a subgroup of patients who significantly lack collateral flow to the region supplied by the P1 perforators, and they do not tolerate any length of upper BA temporary occlusion.