Natalizumab Treatment of Progressive Multiple Sclerosis

Inclusion Criteria: * Age between 19 and 55 years * Progressive disease course of multiple sclerosis (primary or secondary) * Duration of progressive phase of at least 1 year * Progression of \> 1 EDSS point during the last 2 years (\>½ EDSS point if EDSS \> 5,5) * EDSS \</= 6.5 * Written and informed consent Exclusion Criteria: * Pregnancy, breast-feeding or lack of anti.conception for fertile women. * Attack during the last month before inclusion. * Treatment with methylprednisolone during 3 months before inclusion. * Treatment with interferon-beta, glatirameracetate, immunoglobulin G or other immune-modulating treatment 3 months prior to inclusion. * Treatment with mitoxantrone, cyclophosphamide, azathioprine or other strong immunosuppressive drug 6 months prior to inclusion. * Prior experimental treatment with strong immunosuppressive drug which the treating physician means will influence the results of the trial. * Diseases associated with immunodeficiency. * Treatment with other anticoagulant than aspirin. * Current malign disease. * Diabetes Mellitus or other autoimmune disease. * Renal insufficiency or creatinine \> 150 μmol/l. * Travel in tropical areas 3 months prior to inclusion. * Acute or chronic infectious diseases, which the treating physician finds relevant (e.g.hepatitis B virus, hepatitis C virus, HIV). * Psychiatric disease or other circumstances that may limit the patients participation in the trial. * Contraindication for MRI scan or gadolinium contrast . * Known hypersensitivity to natalizumab.