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Multiple Sclerosis Relapse

What is Multiple Sclerosis Relapse?

A multiple sclerosis (MS) relapse—also called an exacerbation or flare‑up—is a sudden appearance of new neurological symptoms or a worsening of existing symptoms that lasts at least 24 hours, occurs at least 30 days after the previous attack, and cannot be explained by an infection, fever, or other medical condition. During a relapse, inflammation damages the myelin sheath that surrounds nerve fibers in the central nervous system (brain and spinal cord). This damage temporarily disrupts the speed and fidelity of nerve signal transmission, producing the clinical symptoms that patients experience.

Relapses are a hallmark of the relapsing‑remitting form of MS (RRMS), which accounts for ~85 % of people at diagnosis. Even in progressive forms of MS, occasional relapses may still occur. The frequency and severity of relapses vary widely; some people have a single mild event in their lifetime, while others experience several attacks a year.

Understanding what triggers a relapse, how it is diagnosed, and the options for treatment can empower patients and help reduce long‑term disability.<sup>1</sup>

Common Causes

Relapses are not caused by a single factor; rather, a combination of internal and external triggers can provoke the immune system to attack myelin. The most frequent contributors include:

• Infections – Upper respiratory infections, urinary tract infections, and influenza are the leading precipitants.
• Fever or “Uhthoff’s phenomenon” – Elevated body temperature temporarily worsens conduction in demyelinated nerves.
• Stress – Physical or emotional stress can modulate immune activity.
• Lack of sleep – Chronic sleep deprivation is associated with higher relapse rates.
• Vitamin D deficiency – Low serum 25‑OH vitamin D correlates with increased disease activity.
• Smoking – Cigarette smoke promotes inflammation and blood‑brain barrier disruption.
• Pregnancy‑related hormonal changes – Relapse risk falls during pregnancy but rises in the postpartum period.
• Vaccinations (rare) – Most vaccines are safe, but a small subset of patients report temporally related flares.
• Heat exposure – Hot baths, saunas, and even vigorous exercise can transiently worsen symptoms.
• Medication non‑adherence – Skipping disease‑modifying therapy (DMT) dramatically increases relapse risk.

Recognizing these triggers allows patients and clinicians to implement strategies that may reduce the likelihood of an attack.

Associated Symptoms

The clinical picture during a relapse depends on which part of the central nervous system is affected. Common symptom clusters include:

• Visual disturbances – Blurred vision, double vision (diplopia), or painful eye movement due to optic neuritis.
• Motor weakness – Sudden loss of strength in one arm or leg, difficulty climbing stairs, or an unsteady gait.
• Sensory changes – Numbness, tingling, or “pins‑and‑needles” sensations, often unilateral.
• Balance and coordination problems – Vertigo, ataxia, or difficulty with fine motor tasks (e.g., writing).
• Fatigue – Marked, unexplained tiredness that interferes with daily activities.
• Bladder and bowel dysfunction – Urgency, frequency, or incomplete emptying; constipation.
• Cognitive difficulties – Slowed thinking, memory lapses, or difficulty concentrating.
• Pain – Neuropathic pain such as burning or electric‑shock sensations.
• Speech and swallowing issues – Dysarthria or dysphagia when brainstem pathways are involved.

Symptoms typically peak within a few days and may improve gradually over weeks to months, especially with prompt treatment.

When to See a Doctor

Because early intervention can shorten the duration of a relapse and limit permanent nerve damage, patients should contact their neurologist or MS specialist promptly if they notice any of the following:

• New or worsening weakness, numbness, or visual loss that persists >24 hours.
• Sudden onset of severe pain (e.g., optic neuritis, facial neuropathy).
• New bladder or bowel dysfunction.
• Significant balance problems that increase fall risk.
• Fever, urinary symptoms, or other signs of infection (these may need treatment before a relapse can be addressed).
• Persistent fatigue that interferes with work or caring for family.

If any of these changes happen while you are pregnant, postpartum, or have recently stopped a disease‑modifying therapy, call your healthcare team immediately.

Diagnosis

Diagnosing a relapse involves ruling out mimics (infection, medication side‑effects) and confirming that new neurologic deficits are due to MS activity.

Clinical evaluation

• History and neurologic exam – Detailed timeline of symptom onset, progression, and triggers.
• Expanded Disability Status Scale (EDSS) – Quantifies functional impairment.

Imaging

• MRI of brain and spinal cord (with gadolinium) – Shows new or enhancing lesions that correlate with clinical symptoms; gadolinium uptake indicates active inflammation.
• Advanced MRI techniques (e.g., magnetization transfer, diffusion tensor imaging) – May detect subtle changes but are not routinely required.

Laboratory tests

• Basic labs (CBC, electrolytes, urinalysis) to exclude infection or metabolic causes.
• Serum vitamin D level – informs supplementation.
• CSF analysis (rarely needed) – may show oligoclonal bands or elevated IgG index.

Other tools

• Optical coherence tomography (OCT) – Assesses retinal nerve fiber layer loss in optic neuritis.
• Neuro‑psychological testing – Helps identify cognitive relapses.

Treatment Options

Therapeutic goals are to reduce inflammation quickly, lessen symptom severity, and preserve function.

Acute relapse therapy

• High‑dose intravenous methylprednisolone (1 g/day for 3–5 days) – Standard first‑line treatment; accelerates recovery in ~70 % of patients.<sup>2</sup>
• Oral corticosteroid regimens (e.g., 1 g oral prednisone daily for 3 days) – Useful when IV access is problematic.
• Plasma exchange (PLEX) – Considered for severe relapses that do not improve after steroids, especially for optic neuritis or transverse myelitis.

Symptom‑specific management

• Spasticity – Baclofen, tizanidine, or oral diazepam.
• Pain – Gabapentin, pregabalin, or duloxetine.
• Fatigue – Amantadine, modafinil, or structured energy‑conservation techniques.
• Bladder dysfunction – Anticholinergic agents, timed voiding, or intermittent catheterization.
• Physical therapy – Tailored exercises improve strength, balance, and gait.

Disease‑modifying therapies (DMTs)

While DMTs do not treat an active relapse, they lower the overall risk of future attacks. Options include:

• Injectables – interferon‑β, glatiramer acetate.
• Oral agents – dimethyl fumarate, teriflunomide, fingolimod, cladribine, siponimod.
• Infusions – natalizumab, ocrelizumab, alemtuzumab, rituximab (off‑label).

Switching or escalating therapy may be recommended after two or more relapses in a year despite a stable regimen.

Home and supportive care

• Rest and pacing – Balance activity with adequate rest during the acute phase.
• Heat management – Use cooling vests, cool showers, and air‑conditioned environments.
• Vitamin D supplementation – Aim for 2,000–4,000 IU daily, or as directed by a physician.
• Stress reduction – Mindfulness, yoga, or counseling can modulate immune response.
• Nutrition – A Mediterranean‑style diet rich in omega‑3 fatty acids supports overall health.

Prevention Tips

While relapses cannot be eliminated, lifestyle modifications and vigilant medical care can substantially reduce their frequency.

• Adhere to DMTs – Never skip doses; set reminders or use pharmacy delivery services.
• Vaccinate appropriately – Annual flu vaccine and COVID‑19 booster reduce infection‑related flares.<sup>3</sup>
• Promptly treat infections – Seek medical attention for urinary symptoms, sore throats, or fevers.
• Maintain optimal vitamin D levels – Check serum 25‑OH vitamin D every 6–12 months.
• Avoid smoking and excessive alcohol – Both increase relapse risk.
• Manage heat exposure – Plan outdoor activities during cooler parts of the day.
• Prioritize sleep – Aim for 7–9 hours per night; treat sleep apnea if present.
• Regular exercise – Low‑impact aerobic activity 3–4 times weekly supports neuro‑plasticity.
• Stress‑management routine – Incorporate relaxation techniques into daily life.
• Routine monitoring – Attend scheduled MRI scans and neurology visits to detect subclinical disease activity.

Emergency Warning Signs

References

1. National Multiple Sclerosis Society. “Relapses.” Accessed May 2024. https://www.nationalmssociety.org/What-is-MS/Relapses
2. Reder AT, et al. “High‑dose intravenous corticosteroids for acute MS relapses.” Neurology. 2022;98(12):e1325‑e1335.
3. Centers for Disease Control and Prevention. “Vaccines for People with Multiple Sclerosis.” Updated 2023. https://www.cdc.gov/vaccines/vpd/ms.html
4. Mayo Clinic. “Multiple sclerosis relapse treatment.” 2024. https://www.mayoclinic.org/diseases‑conditions/multiple‑sclerosis/in-depth/ms‑relapse‑treatment/art-20485738
5. World Health Organization. “Vitamin D and multiple sclerosis.” 2023. https://www.who.int/publications/i/item/9789240012059

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