1 Department of Neurology, Dell Medical School, University of Texas, Austin, Texas.
2 Division of Child Neurology, Departments of Pediatrics and Neurology, Memorial Sloan Kettering Cancer Center, Weill Cornell Medical College, New York, New York.
3 Departments of Neurology and Pediatrics, University of Washington, Seattle, Washington, and Department of Pediatrics, Duke University, Durham, North Carolina. Electronic address: sgospe@uw.edu.