1. From the Divisions of Neurology (L.A.B., R.N.I., D.J.L., S.E.S.) and Neurosurgery (P.B.S.), The Children’s Hospital of Philadelphia, Philadelphia, Pa; the Department of Neurology (S.E.K., M.T.M., S.R.M.), The Hospital of the University of Pennsylvania, University of Pennsylvania School of Medicine, Philadelphia, Pa; and the Department of Neurology and Division of Pediatric Neurology (L.C.J.), Johns Hopkins University School of Medicine, Baltimore, Md.