1. From the Departments of Neurology, University Hospitals, Frankfurt (T.N.-H., O.C.S.), Mannheim (A.G., K.S.), Hamburg (J.R.), Düsseldorf (M.S.), Berlin (C.N., A.V.), and Heidelberg (P.D.S.); and the Departments of Neuroradiology, University Hospitals, Heidelberg (J.B.F.), Hamburg (T.K.), and Frankfurt (R.d.M.).