1. From the Departments of Neurology (L.H.S., Y.L., J.C., Y.C., C.Z., M.C.) and of Biostatistics and Research Epidemiology (A.K., M.L.), Henry Ford Hospital, Detroit, Mich; Theradigm Inc (S.S.-B.), Baltimore, Md; and the Department of Physics (M.C.), Oakland University, Rochester, Mich.