Prehospital Prediction of Large Vessel Occlusion in Suspected Stroke Patients

Recent advances in endovascular thrombectomy have made acute ischemic stroke due to a large vessel occlusion more treatable than ever. Rapid access to treatment remains paramount and multiple large vessel occlusion prediction scales have been created to enhance prehospital identification and triage of these patients. This review summarizes the current state of large vessel occlusion prediction scales, proposes a set of ideal scale features, and discusses the future of these scales and prehospital neurological emergency response systems. A meta-analysis of the available data concluded that none of the currently published scales are more accurate than the others. However, other studies provide insight into important qualitative features beyond accuracy. At present, only a few large vessel occlusion prediction scales have been studied in the necessary prehospital suspected stroke patient population. Among these small studies, 26-51% of patients identified by scales had large vessel occlusions and 63-84% qualified for triage to a Comprehensive Stroke Center. Valuable scale features include binary scoring, inclusion of gaze deviation and arm weakness, exclusion of neglect, and prehospital validation in a suspected stroke cohort. Patients with neurological emergencies that mimic large vessel occlusion, such as intracranial hemorrhage, may also benefit from triage to Comprehensive Stroke Centers. Prehospital triage is more complex than ever and guidelines, tools, and systems continue to evolve.