[1] Guys Kings & St Thomas Sch Med, Dept Neuroimmunol, Guys Hosp, London SE1 9RT, England
[2] Univ Glasgow, So Gen Hosp, Dept Neurol, Glasgow, Lanark, Scotland
[3] Univ Catholique Louvain, Clin Univ St Luc, Neurol Serv, B-1200 Brussels, Belgium
[4] Osped San Raffaele, Dipartimento Sci & Technol, Biomed Clin Neurol 4, Milan, Italy
[5] Hosp Univ Sta Creu & St Pau, Serv Neurol, Barcelona, Spain
[6] Univ Milan, Osped Maggiore Policlin, Inst Clin Neurol, Milan, Italy
[7] Erasmus Med Ctr Rotterdam, Dept Neurol, Rotterdam, Netherlands
[8] Univ Athens, Sch Med, Eginit Univ Hosp, Athens, Greece
[9] NIH, Neuromusc Dis Sect, Bethesda, MD 20892 USA
[10] Charles Univ Hosp, Sch Med 2, Prague, Czech Republic
[11] PHLS, Stat Unit, London, England