Laterality is an Independent Predictor of Endovascular Thrombectomy in Patients With Low National Institute of Health Stroke Scale

Abstract

ObjectiveEndovascular thrombectomy (ET) for acute ischemic stroke (AIS) due to large-vessel occlusion (LVO) is offered to select patients meeting strict criteria. One of the criteria is stroke severity as indicated by the National Institute of Health Stroke Scale (NIHSS). Inherently, NIHSS is biased towards left hemisphere strokes (LHS) with median NIHSS score 4 points higher than right hemisphere strokes (RHS). This may potentially affect clinical decision making and thrombectomy eligibility. We sought to test this hypothesis. MethodsData were analyzed from consecutive AIS patients with LVO admitted to our comprehensive stroke center (June 2015-December 2016). Following variables were studied: NIHSS score, occlusion location, time to presentation, and treatment received. ResultsThree hundred and fifty-one proximal-anterior circulation LVOs (ACLVO) were identified. 211 patients harboring a proximal ACLVO, were treated <24-hour from symptom onset, had a baseline mRS 0-1, ASPECTS ≥6, and NIHSS score ≥6. One hundred and twelve (53%) were LHS and 99 (47%) were RHS. ET was performed in 87% of LHS and 78% of RHS (P = .09). In the NIHSS score >12 range, 88% of LHS and RHS received ET (P = .93). In the NIHSS score 6-12 range, 81% of LHS and 52% of RHS received ET (P = .03). ConclusionsWe find comparable rates of ET between right and LHS in patients with high NIHSS but lower rates of ET of RHS than LHS in patients at lower NIHSS. A hemisphere-laterality based adjustment to the NIHSS may better identify the full extent of patients that may benefit from ET.