The patients will continue their AVONEX® intramuscular injections of 30 micrograms (administered by patient or caregiver) on a weekly basis. The methylprednisolone treatment and methotrexate infusion will be performed in our outpatient infusion center. The patient will be required to complete a patient diary during the course of the trial, participate in and keep all scheduled appointments, and to inform the research staff and physician of any change in concomitant medications or adverse events that they may experience.