Question category: Neurology
A 32 year old female presents with acute painful reduction of vision in her right eye and double vision. There was a previous investigation of paraesthesia of the leg and transverse myelitis which both self resolved. A lumbar puncture reveals oligoclonal bands and an MRI reveals plaques in the periventricular region, brainstem and cervical cord. There is a delay in visual evoked response. Which treatment can be used to try to reduce relapses long term?