[1] Hosp Clin, Porto Alegre, RS, Brazil
[2] Univ Fed Sao Paulo, Sao Paulo, Brazil
[3] Univ Metropolitana Santos, Santos, Brazil
[4] Hosp Britan, Buenos Aires, DF, Argentina
[5] Univ Guadalajara, CUCS, Guadalajara 44430, Jalisco, Mexico
[6] Inst Mexicano Seguro Social, Hosp Especialidades, Puebla, Mexico
[7] Colombian Multiple Sclerosis Res & Treatment Comm, Bogota, Colombia
[8] Hosp Clin Montevideo, Montevideo, Uruguay
[9] Hosp Patrocinio Penuela Ruiz, San Cristobal, Venezuela
[10] Inst Invest Med Alfredo Lanari, Buenos Aires, DF, Argentina
[11] Univ Los Andes, Santiago, Chile
[12] Univ Peruana Cayetano Heredia, Lima, Peru