1. Department of Neurological Sciences, University La Sapienza, Rome, Italy
2. National Center of Epidemiology, National Institute of Health, Rome, Italy
3. Department of Neurological Sciences, University Federico II, Naples, Italy
4. Neurology Service, Misericordia Hospital, Grosseto, Italy
5. Department of Neurological Sciences, University of Birmingham, Birmingham, United Kingdom
6. Institute of Neurology, University of Pisa, Pisa, Italy
7. Institute of Neurology, University of Bari, Bari, Italy
8. Department of Neurology, Medical University of Lübeck, Lübeck, Germany