[1] Univ Milan, Osped Maggiore Policlin, Dipartimento Sci Neurol, Fdn IRCCS, I-20122 Milan, Italy
[2] Drexel Univ, Sch Biomed Engn Sci & Hlth Syst, Philadelphia, PA 19104 USA
[3] Fdn Hosp Nacl Paraplej Invest & Integrac, SESCAM, Toledo, Spain
[4] Univ Milan, Ist Fisiol Umana 2, I-20122 Milan, Italy