Can You Get a Flare of MS?
Yes, patients with multiple sclerosis absolutely can and do experience flares (relapses), which are a defining hallmark of relapsing-remitting MS (RRMS), the most common form of the disease affecting approximately 85% of MS patients. 1, 2
What Constitutes an MS Relapse
An MS attack, relapse, or exacerbation refers to an episode of neurological disturbance caused by inflammatory demyelinating lesions. To qualify as a true relapse, specific criteria must be met 1:
- Duration: Symptoms must last at least 24 hours
- Objective findings: Clinical examination must reveal objective neurological deficits, not just subjective complaints
- Timing: At least 30 days must separate the onset of one relapse from the onset of another
- Exclusion of pseudoattacks: The event cannot be triggered by fever, infection, or elevated core body temperature
Single paroxysmal episodes (like one tonic spasm) do not constitute a relapse, but multiple episodes occurring over at least 24 hours do. 1
Common Relapse Symptoms
Both clinicians and patients recognize classic neurologic symptoms as indicative of relapses 3:
- Sensory changes (numbness, tingling)
- Vision problems (optic neuritis)
- Walking difficulties and motor weakness
- Balance and coordination issues
- Fatigue, pain, and cognitive changes (though these are less quantifiable)
Clinical Course and Recovery
Relapses are characteristic of relapsing-remitting MS, where patients experience acute inflammatory episodes followed by periods of remission. 2 The recovery pattern is well-documented 4:
- 78% of patients show improvement at 3 months
- 86% improve by 6 months
- 55% achieve complete recovery to pre-relapse baseline at 3 months
- 71% achieve complete recovery by 6 months
- Recovery typically stabilizes after 6 months
Importantly, incomplete remissions are often linked to subsequent relapses occurring in the following months rather than the characteristics of the initial relapse itself. 4
Critical Pitfalls to Avoid
Distinguishing true relapses from pseudorelapses is essential 5, 6:
- Pseudorelapses: Temporary worsening of old symptoms triggered by heat, fever, infection, or stress—these do not represent new inflammatory activity
- Symptom fluctuation: Day-to-day variations in existing symptoms
- True relapses: New symptoms or clear worsening of old symptoms with objective clinical findings
Missed or unrecognized relapses have broad implications for patient care, prognosis, and clinical trial conduct. 3 Many relapses go unrecognized because patients may not report less quantifiable symptoms like fatigue or cognitive changes, or may attribute symptoms to other causes.
Treatment Implications
Most MS exacerbations should be treated, as treatment shortens disability duration and helps patients regain control over their disease. 6 The standard approach involves systemic corticosteroids, though the optimal route and dosing remain debated. For steroid-resistant relapses, plasma exchange may be considered.
Disease Monitoring
After a relapse, close monitoring is crucial 7:
- Some patients, particularly those with MOG-antibody associated disease, have high risk of flare-ups after steroid cessation and require careful steroid tapering
- MRI can detect new lesions even without clinical symptoms, providing evidence of ongoing disease activity
- The presence of new lesions on follow-up MRI, particularly in the spinal cord and brainstem, strongly predicts long-term disability 8, 9
The relapsing nature of MS underscores the importance of disease-modifying therapies to reduce relapse frequency and severity, ultimately preventing long-term disability accumulation.