1. From the Divisions of Neurology (L.A.B., D.J.L., S.E.S., A.M.F., R.N.I.), Neurosurgery (P.B.S., G.G.H.), and Neuroradiology (R.A.Z.), The Children’s Hospital of Philadelphia, Philadelphia, Pa; the Department of Neurology (S.E.K.), The Hospital of the University of Pennsylvania, Philadelphia, Pa; and the Department of Neurology (L.C.J.), Division of Pediatric Neurology, Johns Hopkins University School of Medicine, Baltimore, Md.