Feasibility of non-invasive neuromonitoring using BIS and NIRS during endovascular treatment of acute ischemic stroke.

Background: Endovascular thrombectomy (EVT)-often combined with intravenous thrombolysis-is the standard of care for acute ischemic stroke (AIS) secondary to large vessel occlusions (LVO). While indications keep expanding, the feasibility and utility of intra-procedural neuromonitoring of the sedated patient has neither been clarified nor characterized.

Objective: To evaluate the feasibility of near-infrared spectroscopy (NIRS) for cortical oxygenation and bispectral index (BIS) for electroencephalographic function as non-invasive neuromonitoring tools for AIS patients undergoing EVT, and assess their utility in predicting successful recanalization.

Methods: We extracted data on all patients receiving continuous NIRS and/or BIS monitoring in the Sedation versus Intubation for Endovascular Stroke TreAtment (SIESTA) clinical trial. SIESTA randomized AIS patients undergoing EVT for anterior proximal LVO to general anesthesia versus conscious sedation. For this analysis, the primary outcomes included changes in NIRS and BIS values pre- and post-recanalization and associations of parameter changes with successful or unsuccessful recanalization outcomes. Statistical analysis was performed using a Wilcoxon signed rank tests.

Results: Of the 150 patients, 66 were monitored continuously with NIRS, and 50 with BIS. An increased NIRS-derived cerebral tissue oxygenation (stated as tissue saturation index - TSI) was observed in affected hemisphere following successful recanalization, as well as a significant reduction in the difference between affected and unaffected hemispheres. In contrast, no significant changes were observed with BIS monitoring between pre- and post-recanalization status.

Conclusion: In this post-hoc analysis, changes in NIRS monitoring were associated with successful reperfusion. Non-invasive oximetry by NIRS may serve as a valuable tool during and after mechanical thrombectomy to detect and respond to an insufficient perfusion or re-occlusion.