Tysabri (Natalizumab) is a New Medication available now for Multiple Sclerosis. Do your own Due Diligence but I believe that Tysabri is the superior medication on the market for this indication and that Elan Pharmaceuticals, its inventor, will be the top Neuroscience Company by 2015. This description is worth what you paid for it, so again, please discuss with your doctor or your financial planner. Heheeheee.