1. Division of Pediatric Neurology University of Catania Catania,, Italy
2. Department of Neurology, Neuroscience and Pediatrics The New York Hospital-Cornell University Medical Center New York, New York
3. Istituto di Bioimmc~gini e Fisiopatologia del Sisteme Nervoso Centrale, Consiglio Nazionale delle Ricerche Catania, Italy