Hypothesis: Somatosensory evoked potentials (SEPs), as surrogate of cerebral blood flow, may predict immediate and long term clinical outcome in patients with acute ischemic stroke undergoing mechanical thrombectomy.
Methodology: Median nerve SEPs were monitored before and continously during mechanical trhombectomy in acute ischemic stroke patients with proximal anterior large vessel occlusion. The target signal was the patency of the N20 wave ipsilateral to the stroke site. Dramatic recovery was defined as improvement ≥ 10 or NIHSS score 0-1 at 24 hours and good functional outcome as modified Rankin scale 0-2 at 90 days.
Results: A total of 41 patients were monitored with SEPs. Six patients were excluded because of traces artifacts. At the beginning of the procedure, patent N20 was observed in 25 patients and absence of N20 wave in 10 patients. Age, gender, median NIHSS score (17 vs 17), site of vessel occlusion, IV tPA use, ASPECTS score and onset-to-groin puncture time were comparable between patients with patent and absent N20 wave. Patent N20 group showed better median NIHSS score at 24 hours (6 [2-18] vs 18 [11-24], p=0.031) and a no significant trend to a higher rate of dramatic recovery (52% vs 25%, p=0.087). At the end of the procedure, patent N20 was found in 25 patients (3 recovered N20 and 3 lost N20 wave). Complete revascularization (TICI 2b,3) was achieved in 22/25 patent N20 group and 4/10 no patent N20 group. Patent N20 at the end of the procedure was significantly associated with dramatic recovery (60% vs 0%, p=0,001) and good functional outcome (68% vs 0%, p=0,001)
Conclusions: SEPs recording is a non-invasive and feasible test that provides real time data in the angiosuite, even in patients under general anesthesia in which neurological deficit cannot be evaluated. Patency of SEP at the beginning but especially at the end of the procedure is related with immediate and long term outcome, despite achieving complete revascularization.