Multiple sclerosis (MS) relapses are defined as new or worsening neurologic deficits lasting 24 hours or more in the absence of fever or infection. Symptoms may be visual, motor, sensory, balance or cognitive. It is a clinical diagnosis, but the presence of a new gadolinium-enhancing lesion on MRI can be used as a radiologic marker of an MS relapse. However, it is unclear whether asymptomatic lesions should be treated, making it prudent to rely on the clinical evaluation rather than the MRI for diagnosis.
Moderate to severe relapses should be treated within 1 week of onset. The mainstay of treatment for relapses is IV methylprednisolone, usually dosed at 500mg to 1g per day for 3-7 days.
Similar symptoms occurring in the presence of fever, heat exposure, stress or infection (such as urinary or upper respiratory tract infections) are "pseudoexacerbations", and should not be treated as an MS relapse.
