Clinical Presentation Additional Data Needed * 2 or more attacks (relapses) * 2 or more objective clinical lesions None; clinical evidence will suffice (additional evidence desirable but must be consistent with MS) * 2 or more attacks * 1 objective clinical lesion Dissemination in space, demonstrated by: * MRI * or further clinical attack involving different site * 1 attack * 2 or more objective clinical lesions Dissemination in time, demonstrated by: * MRI * or second clinical attack * or CSF-specific oligoclonal bands * 1 attack * 1 objective clinical lesion (monosymptomatic presentation) Dissemination in space demonstrated by: * MRI * or an additional clinical attack implicating a different CNS site and Dissemination in time demonstrated by: * MRI * or second clinical attack * or CSF-specific oligoclonal bands Insidious neurological progression suggestive of MS (primary progressive MS) One year of disease progression (retrospectively or prospectively determined) and Two of the following: a. Positive brain MRI (nine T2 lesions or four or more T2 lesions with positive VEP) b. Positive spinal cord MRI (two focal T2 lesions) c.