This is a double blind, randomized, parallel group design placebo-controlled mono-center study. Patients will be evaluated within twelve months of CIS onset. Patients with at least 2 silent ovoid T2 bright areas in the deep white matter on their clinic brain MRI scan will be offered participation in the study. Patients will be randomized to oral riluzole or placebo (1:1). Patient will take 50 mg of riluzole or placebo once a day for one month. If 50 mg once a day is well tolerated, patients will then go on 50 mg twice daily for the rest of the study. They will start Avonex (Interferon beta 1a) therapy 30 mcg IM once weekly 3 months after study drug (riluzole or placebo) is initiated if their liver function has remained normal.