1. From the Division of Neurology (N.S.A., A.M.G.-C., M.D., R.R.C., D.J.D.), Department of Anesthesia and Critical Care Medicine (A.A.T.), and Biostatistics and Data Management Core (H.Z., R.G.), The Children's Hospital of Philadelphia; and Department of Neurology (N.S.A., R.R.C., D.J.D.), The University of Pennsylvania School of Medicine, Philadelphia.