1. Hospital de Neurorehabilitación Institut Guttmann, Barcelona, Spain,
2. Hospital de Neurorehabilitación Institut Guttmann, Barcelona, Spain
3. Unitat d'EMG, Servei de Neurologia, Hospital Clinic, Barcelona, Spain
4. Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA, Burke Medical Research Institute, White Plains, New York, USA
5. Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA, Boston University School of Medicine, Boston, Massachusetts, USA
6. Hospital de Neurorehabilitación Institut Guttmann, Barcelona, Spain, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA