During the pre-treatment phase, patients undergo neurological exams, including the extended disability status scale (EDSS), Ambulation Index (AI), disease steps (DS) scale MS functional composite score, PASAT, 9 hole peg test, and the 25 foot walking time. A 12-lead electrocardiogram (EKG) and chest x-ray are performed. Serum chemistry is assessed as well as electrolyte and thyroid stimulating hormone (TSH) levels. A brain MRI (with and without gadolinium), urinalysis, and urine pregnancy test (for women of reproductive potential) are performed. Blood is collected for mechanistic studies. In the treatment phase, patients are assigned randomly to 1 of 2 study arms: