1. From the Division of Research, Kaiser Permanente Northern California, Oakland (M.N.N.-H., A.L.A., A.C.F., A.E.); Departments of Neuroscience (A.C.F., V.A.R.) and Emergency Medicine (S.B.), Kaiser Permanente, Redwood City, CA; Departments of Neurology (M.N.N.-H., J.G.K.) and Radiology (A.C.K.), Kaiser Permanente, Walnut Creek, CA; and Department of Emergency Medicine, Kaiser Permanente, Oakland, CA (J.W.M.).