1 Department of Medical Sciences and Public Health, Institute of Neurology, University Hospital D. Casula, Monserrato, Cagliari, Italy. marcello.mas@tiscali.it.
2 Department of Medical Sciences and Public Health, Institute of Neurology, University Hospital D. Casula, Monserrato, Cagliari, Italy.
3 Department of Medical Sciences and Public Health, Institute of Neurology, University of Cagliari, Cagliari, Italy.