The Fondazione Italiana Sclerosi Multipla (FISM) Onlus, in its capacity as Promoter of this study, wishes, responsibly, to produce the best possible answer for people with MS all over the world. It therefore feels that it is necessary to proceed with the utmost scientific thoroughness, initially by means of a large-scale sample study for evaluating the prevalence of venous abnormalities in MS compared with that observed in normal controls and in controls with other diseases of the nervous system. In this context, the features of this study that distinguish it from previous studies and from the current state of knowledge are the following: