1. From the Department of Neurology (J.A.V.), Emory University School of Medicine, Atlanta; Departments of Neurology (R.A.P., A.G.H., D.R.L., W.W.A.) and Ophthalmology (A.G.H.), University of Pennsylvania Perelman School of Medicine, Philadelphia; and Division of Neurology (D.R.L.), Department of Pediatrics, Children's Hospital of Philadelphia, PA.