1. Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy
2. Institute of Neurology, University Hospital of Cagliari, Cagliari, Italy
3. Institute of Neurology, San Paolo Hospital, Bari, Italy
4. ALS Center, Rita Levi Montalcini Department of Neurosciences, University of Turin, Turin, Italy, and
5. Amyotrophic Lateral Sclerosis Center, University of Cagliari, Cagliari, Italy