Neurophysiological monitoring during endovascular treatment of brain arteriovenous malformations: A meta-analysis

Background: Treatment of brain arteriovenous malformations (b-AVM) carries a risk of iatrogenic injury to eloquent brain regions. Intraoperative neuro-monitoring (IONM) has increasingly been used to monitor spontaneous or evoked neural activity during neurosurgery, but its use is not as well characterized in the endovascular treatment (EVT) of b-AVMs. We aimed to provide a systematic review and meta-analysis of studies reporting any neurological deficit after b-AVM embolization with IONM, with or without provocative test (PT), and no-IONM. Methods: This systematic review followed the PRISMA guidelines. Medline, EMBASE, and Scopus were searched from conception until March 1, 2022 for studies evaluating EVT with IONM and PT. Primary outcome was the rate of postoperative neurological deficits in EVT with IONM versus no-IONM, while secondary outcome was the subanalysis of IONM with or without PT. Meta-analysis was performed using the Mantel-Haenszel method and random effects modeling. Results: Six studies reached synthesis. Out of a total of 192 EVT, 14 events occurred. Results demonstrated a nonsignificant trend favoring IONM compared to no-IONM to prevent neurological deficits (OR 0.09, 95% CI 0-4.68). Among the EVT with IONM, PT was done in 411 branches with 10 events (0.2%) despite a negative PT. There was a nonsignificant trend favoring IONM plus PT compared to IONM without PT (OR 0.16, 95% CI 0.02-1.07). Conclusions: Our study suggests that b-AVM EVT with IONM plus PT might reduce rates of postprocedural neurological deficits compared with EVT without IONM. Further studies are needed to confirm these results.