What are Multiple Sclerosis (MS) relapses?

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Last updated: March 27, 2025View editorial policy

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From the Guidelines

MS relapses are episodes of new or worsening neurological symptoms in multiple sclerosis that last at least 24 hours and occur in the absence of fever or infection. These episodes are characterized by an increase in disease activity, with the immune system attacking the protective myelin coating around nerve fibers in the central nervous system, causing inflammation and disrupting nerve signal transmission 1. The diagnostic criteria for MS relapses, as outlined in the guidelines from the international panel on the diagnosis of multiple sclerosis, emphasize the importance of expert clinical assessment to distinguish true relapses from pseudoattacks, such as those caused by changes in core body temperature or infection 1.

Key Characteristics of MS Relapses

  • Last for at least 24 hours
  • Occur in the absence of fever or infection
  • May be preceded by subjective reports from the patient, but require objective clinical findings to confirm the diagnosis
  • Can manifest as a variety of neurological symptoms, including vision problems, muscle weakness, numbness or tingling, balance issues, fatigue, and cognitive difficulties
  • Typically develop over days to weeks and may last several weeks to months
  • Are followed by periods of partial or complete recovery (remission)

Treatment and Management

Treatment for acute relapses often involves high-dose corticosteroids, such as methylprednisolone, to reduce inflammation and speed recovery 1. It is essential to contact a healthcare provider promptly if a relapse is suspected, as early treatment can improve outcomes and prevent permanent damage. Distinguishing true relapses from temporary symptom fluctuations (pseudorelapses) caused by heat, stress, or infections is crucial for appropriate management.

From the FDA Drug Label

In Study 1 and Study 2, intravenous ocrelizumab significantly lowered the annualized relapse rate and the proportion of patients with disability progression confirmed at 12 weeks after onset compared to REBIF. The primary outcome of both Study 1 and Study 2 was the annualized relapse rate (ARR) Both studies included patients who had experienced at least one relapse within the prior year, or two relapses within the prior two years,

Multiple Sclerosis (MS) relapses are episodes of worsening neurological function that occur in patients with MS, characterized by an increase in symptoms or disability. In the context of the studies, relapses are defined as events that occur when a patient experiences a worsening of their MS symptoms, which can be confirmed by an increase in the Expanded Disability Status Scale (EDSS) score. The annualized relapse rate (ARR) is a measure of the frequency of these relapses over a period of time. 2

From the Research

Definition and Characteristics of MS Relapses

  • MS relapses are a hallmark of multiple sclerosis (MS) and are often associated with significant functional impairment and decreased quality of life 3, 4, 5.
  • Relapses are characterized by new or worsened neurologic symptoms, and are sometimes referred to as exacerbations or attacks 5.
  • Most MS exacerbations are followed by a period of repair leading to clinical remission; however, residual deficits may persist after MS relapse and contribute to the stepwise progression of disability 3.

Treatment and Management of MS Relapses

  • Treatment of MS relapses is important as it helps to shorten the duration of disability associated with their course 3, 4.
  • Systemic corticosteroids and adrenocorticotropic hormone (ACTH) have broad regulatory approval and remain the most established and validated treatment options for MS relapse 3, 4.
  • High dose short-term oral or intravenous methylprednisolone for 3-5 days can speed up recovery from relapses, but has no influence on the occurrence of new relapses or long-term disability 6.
  • Corticosteroids are considered the cornerstone in the management of acute MS relapses, but many unanswered questions remain when it comes to the exact modalities of administration 7.

Importance of Timely Recognition and Treatment

  • MS relapses need to be recognized in a timely manner and treated using recommended therapeutic methods 3.
  • Adequate management of MS relapses is important, as it may help to shorten and lessen the disability associated with their course 4.
  • Successful treatment of relapse helps patients with MS obtain a vital sense of being able to gain control over the disease, and patients with relapsing MS who receive treatment report better outcomes than those who are simply observed 3.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Acute Multiple Sclerosis Relapse.

Continuum (Minneapolis, Minn.), 2016

Research

Treatment of acute relapses in multiple sclerosis.

Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics, 2013

Research

Relapse management in multiple sclerosis.

The neurologist, 2009

Research

Corticosteroids in the treatment of multiple sclerosis.

Acta neurologica Scandinavica. Supplementum, 2009

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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