[1] Univ Ottawa, Ottawa Hosp, Res Inst, Dept Med, Ottawa, ON, Canada
[2] Hosp Sick Children, Toronto, ON, Canada
[3] Cleveland Clin Fdn, Mellen Ctr Multiple Sclerosis, Cleveland, OH USA
[4] Univ Oxford, John Radcliffe Hosp, Nuffield Dept Clin Neurosci, Oxford, England
[5] Univ Manitoba, Max Rady Coll Med, Rady Fac Hlth Sci, Dept Internal Med, Winnipeg, MB, Canada
[6] Montreal Neurol Inst, Montreal, PQ, Canada
[7] Univ Penn, Perelman Sch Med, Dept Neurol, 3400 Civ Ctr Blvd,Rm 763, Philadelphia, PA 19104 USA
[8] Childrens Hosp Philadelphia, Child Guidance Clin, Philadelphia, PA USA