[1] Inst Politecn Nacl, Acad Fisiol Humana, Escuela Super Med, Plan San Luis & Diaz Miron, Col Casco de Santo Tomas,Del Miguel Hidalgo, Mexico City 11340, Mexico
[2] Inst Mexicano Seguro Social, Hosp Especial Ctr Med Nacl Siglo XXI, Unidad Invest Med Enfermedades Neurol, Ave Cuauhtemoc,330-4 Piso,Col Doctores, Mexico City 06720, Mexico
[3] Inst Nacl Neurol & Neurocirugia Manuel Velasco Sua, Lab Fisiol Formac Reticular, Insurgentes 3877, Mexico City 14269, Mexico