1. Department of Neurology, University of Catania, Via Santa Sofia 78, 95123 Catania, Italy,
2. Department of Neurological Sciences, University of Florence, Viale Morgagni 85, 50100 Florence, Italy
3. Institute of Hygiene, University of Siena, Via Aldo Moro, 53100 Siena, Italy
4. Medical Department, Industria Farmaceutica Serono, Via Casilina 125, 00176 Rome, Italy
5. Department of Critical Area, University of Florence, 50100 Florence, Italy
6. Department of Neurology, ASL 3, 17100 Genova, Italy
7. Department of Neurological and Neuropsychiatric Sciences, University of Bari, Piazza Giulio Cesare 11, 70100 Bari, Italy