1. Departments of Neurology and Pediatrics; Washington University School of Medicine, 660 South Euclid Avenue; Box 8111 St. Louis Missouri 63110 USA
2. Department of Radiology; Beth Israel Deaconess Medical Center; Boston Massachusetts USA
3. Department of Neurology; Beth Israel Deaconess Medical Center; Boston Massachusetts USA
4. Department of Neurology; Boston Children's Hospital; Boston Massachusetts USA