A 25 year old man with a diagnosis of MS had sudden change in neurologic status after discontinuation of natalizumab. He had been on therapy for two years with good response but natalizumab was discontinued due to concerns of increased risk for PML. He switched to glatiramer acetate but after three months from discontinuation of natalizumab, he had acute symptoms of ataxia and fatigue. MRI revealed multiple new T2/FLAIR hyperintensities and T1 enhancing lesions. He was treated with a 5 day course of methylprednisolone and his symptoms promptly resolved (case report and MRI courtesy of Ann Cabot, D.O.).