Acute Multiple Sclerosis Relapse
Summary
An acute multiple sclerosis (MS) relapse (also called an exacerbation or flare) is a sudden worsening of neurological symptoms in someone with MS, caused by new inflammation and damage to the myelin sheath (the protective covering around nerves) in the brain or spinal cord. Think of MS as your nervous system's wiring—the myelin is like insulation around electrical wires. When MS flares, the insulation gets damaged, causing electrical signals to misfire, leading to symptoms like weakness, numbness, vision problems, or balance issues. Relapses are a hallmark of relapsing-remitting MS (the most common type), where symptoms come and go. The severity ranges from mild (slight numbness) to severe (paralysis, vision loss). The key to management is recognizing a true relapse (not a pseudo-relapse from infection or heat), providing high-dose steroids to reduce inflammation, managing symptoms, and preventing future relapses with disease-modifying therapies (DMTs). Most relapses improve significantly with treatment, but some symptoms may persist.
Key Facts
- Definition: Acute worsening of neurological symptoms due to new MS inflammation
- Incidence: Common in relapsing-remitting MS (1-2 relapses/year average)
- Mortality: Very low (relapses themselves), but MS can affect life expectancy
- Peak age: Adults (20-50 years, typical MS age)
- Critical feature: New or worsening neurological symptoms lasting >24 hours
- Key investigation: Clinical diagnosis (usually), MRI if needed
- First-line treatment: High-dose steroids (methylprednisolone), DMTs for prevention
Clinical Pearls
"Not all symptom worsening is a relapse" — Pseudo-relapses (worsening from infection, heat, stress) are common. Always check for infection (especially UTI) before treating as relapse.
"Relapses need to last >24 hours" — Brief symptom fluctuations (hours) are usually not true relapses. True relapses last at least 24 hours and are separated by at least 30 days from previous relapse.
"Steroids speed recovery but don't change long-term outcome" — High-dose steroids (methylprednisolone) help relapses recover faster, but don't prevent future relapses or change long-term disability. DMTs prevent relapses.
"Infection can trigger relapses" — Infections (especially UTIs) can trigger pseudo-relapses or true relapses. Always check for and treat infections.
Why This Matters Clinically
MS relapses are common and can cause significant disability and distress. Early recognition and treatment (steroids) can speed recovery and reduce disability. Preventing relapses with DMTs is crucial for long-term outcomes. This is a condition that neurologists and primary care clinicians manage, and prompt treatment can make a significant difference in recovery.
Incidence & Prevalence
- Overall: Common in relapsing-remitting MS
- Relapse rate: 1-2 relapses/year average (varies widely)
- Trend: Decreasing with DMT use
- Peak age: Adults (20-50 years, typical MS age)
Demographics
| Factor | Details |
|---|---|
| Age | Adults (20-50 years, typical MS age) |
| Sex | Female predominance (MS is more common in women) |
| Ethnicity | Higher in certain populations (Caucasian, Northern European) |
| Geography | Higher in temperate climates |
| Setting | Neurology clinics, general practice |
Risk Factors
Non-Modifiable:
- MS diagnosis (relapsing-remitting type)
- Genetic factors
Modifiable:
| Risk Factor | Relative Risk | Mechanism |
|---|---|---|
| Infection | 2-3x | Triggers inflammation |
| Stress | 1.5-2x | May trigger relapses |
| Heat | 1.5-2x | Worsens symptoms (pseudo-relapse) |
| Stopping DMT | 2-5x | Removes protection |
| Pregnancy (postpartum) | 2-3x | Hormonal changes |
Common Triggers
| Trigger | Frequency | Typical Patient |
|---|---|---|
| Infection | 30-40% | UTI, respiratory infection |
| Stress | 20-30% | Life stress, physical stress |
| No obvious trigger | 30-40% | Spontaneous |
| Heat | 10-20% | Hot weather, fever |
| Stopping DMT | 5-10% | Non-compliance, side effects |
The Relapse Mechanism
Step 1: Immune Activation
- T-cells: Activated, cross blood-brain barrier
- Inflammation: Inflammatory cells enter CNS
- Result: Immune system attacks myelin
Step 2: Demyelination
- Myelin damage: Immune attack damages myelin sheath
- Axon exposure: Nerves become exposed
- Result: Nerve signals disrupted
Step 3: Clinical Manifestation
- Symptoms: Depend on location of damage
- Weakness: If motor pathways affected
- Numbness: If sensory pathways affected
- Vision problems: If optic nerve affected
- Balance problems: If cerebellum affected
Step 4: Recovery (Partial)
- Remyelination: Some myelin repair
- Compensation: Brain adapts
- Result: Symptoms improve, but may not fully recover
Classification by Type
| Type | Mechanism | Clinical Features |
|---|---|---|
| Relapsing-remitting | Relapses with recovery | Most common, relapses come and go |
| Secondary progressive | Relapses become less frequent, disability accumulates | Progressive after initial relapsing phase |
| Primary progressive | No relapses, gradual progression | Less common, gradual decline |
Anatomical Considerations
Common Sites of Relapse:
- Optic nerve: Vision problems (optic neuritis)
- Spinal cord: Weakness, numbness, bladder problems
- Brainstem: Double vision, balance problems
- Cerebellum: Balance, coordination problems
- Brain: Various symptoms depending on location
Why These Areas:
- High myelin content: More myelin = more vulnerable
- Blood-brain barrier: May be more permeable in these areas
Symptoms: The Patient's Story
Typical Presentation:
Common Relapse Presentations:
Optic Neuritis:
Spinal Cord Relapse:
Brainstem Relapse:
Cerebellar Relapse:
Signs: What You See
Vital Signs (Usually Normal):
| Sign | Finding | Significance |
|---|---|---|
| Temperature | Usually normal (may be elevated if infection) | Fever suggests infection (pseudo-relapse) |
| Heart rate | Usually normal | Usually normal |
| Blood pressure | Usually normal | Usually normal |
Neurological Examination:
| Finding | What It Means | Frequency |
|---|---|---|
| Weakness | Motor pathway affected | 50-60% |
| Numbness | Sensory pathway affected | 40-50% |
| Vision problems | Optic nerve affected | 20-30% |
| Balance problems | Cerebellum/brainstem affected | 30-40% |
| Bladder problems | Spinal cord affected | 20-30% |
Signs of Pseudo-Relapse (Infection):
Red Flags
[!CAUTION] Red Flags — Immediate Escalation Required:
- Severe neurological deficit — May need urgent steroids, hospital admission
- Signs of infection (fever, urinary symptoms) — May be pseudo-relapse, needs treatment
- Signs of spinal cord compression — Medical emergency, needs urgent imaging
- Rapidly progressive symptoms — May need urgent treatment
- Altered mental status — May indicate other cause
- Signs of optic neuritis (severe vision loss) — May need urgent steroids
Structured Approach: ABCDE
A - Airway
- Assessment: Usually patent
- Action: Secure if compromised
B - Breathing
- Look: Usually normal
- Listen: Usually normal
- Measure: SpO2 (usually normal)
- Action: Support if needed
C - Circulation
- Look: Usually normal
- Feel: Pulse (usually normal), BP (usually normal)
- Listen: Heart sounds (usually normal)
- Measure: BP (usually normal), HR
- Action: Monitor if severe
D - Disability
- Assessment: Neurological examination
- Action: Assess function, disability
E - Exposure
- Look: Neurological examination
- Feel: Strength, sensation
- Action: Complete neurological examination
Specific Examination Findings
Neurological Examination:
- Cranial nerves: May show abnormalities (optic neuritis, facial weakness)
- Motor: May show weakness
- Sensory: May show numbness
- Reflexes: May be increased (upper motor neuron signs)
- Coordination: May show problems (if cerebellar)
- Gait: May show problems (if balance affected)
Signs of Pseudo-Relapse:
- Fever: Infection
- UTI signs: Frequency, urgency, dysuria
- Other: As appropriate
Special Tests
| Test | Technique | Positive Finding | Clinical Use |
|---|---|---|---|
| Neurological examination | Full neurological exam | Abnormalities consistent with MS | Confirms relapse |
| Urine dipstick | Check for UTI | Positive (infection) | Identifies pseudo-relapse |
| EDSS score | Disability scale | Increased score | Quantifies disability |
First-Line (Bedside) - Do Immediately
1. Clinical Diagnosis (Usually Sufficient)
- History: New or worsening symptoms, >24 hours, separated by >30 days
- Examination: Neurological abnormalities consistent with MS
- Action: Usually sufficient for diagnosis
2. Check for Infection (Important)
- Urine dipstick: Check for UTI
- Other tests: As appropriate
- Action: Rule out pseudo-relapse
Laboratory Tests
| Test | Expected Finding | Purpose |
|---|---|---|
| Urine dipstick | May show infection (if pseudo-relapse) | Rules out pseudo-relapse |
| Full Blood Count | Usually normal | Baseline |
| CRP | May be elevated (if infection) | Identifies infection |
Imaging
MRI Brain/Spine (If Needed):
| Indication | Finding | Clinical Note |
|---|---|---|
| Uncertain diagnosis | New lesions, enhancing lesions | Confirms relapse |
| Severe relapse | New lesions, enhancing lesions | Assesses severity |
| Differential diagnosis | Rules out other causes | Important |
Findings:
- New lesions: New areas of demyelination
- Enhancing lesions: Active inflammation (gadolinium enhancement)
- Old lesions: Previous damage
Diagnostic Criteria
Clinical Diagnosis:
- New or worsening symptoms + >24 hours duration + separated by >30 days + neurological abnormalities = MS relapse
Pseudo-Relapse vs True Relapse:
- Pseudo-relapse: Symptoms worsen from infection, heat, stress (not new inflammation)
- True relapse: New inflammation causing new or worsening symptoms
Severity Assessment:
- Mild: Minimal disability, can function
- Moderate: Significant disability, affects function
- Severe: Severe disability, may need hospital admission
Management Algorithm
SUSPECTED MS RELAPSE
(New/worsening symptoms >24h)
↓
┌─────────────────────────────────────────────────┐
│ CHECK FOR INFECTION │
│ • Urine dipstick (UTI) │
│ • Other tests as needed │
│ • If infection: Treat infection first │
│ • If symptoms persist: True relapse │
└─────────────────────────────────────────────────┘
↓
┌─────────────────────────────────────────────────┐
│ ASSESS SEVERITY │
├─────────────────────────────────────────────────┤
│ SEVERE (severe disability, hospital needed) │
│ → Hospital admission │
│ → IV steroids │
│ → Supportive care │
│ │
│ MILD-MODERATE │
│ → Outpatient management │
│ → Oral steroids (if indicated) │
│ → Supportive care │
└─────────────────────────────────────────────────┘
↓
┌─────────────────────────────────────────────────┐
│ STEROID TREATMENT │
│ • High-dose steroids (methylprednisolone) │
│ • Duration: 3-5 days │
│ • Taper: Usually not needed (short course) │
│ • Mechanism: Reduces inflammation │
└─────────────────────────────────────────────────┘
↓
┌─────────────────────────────────────────────────┐
│ SYMPTOM MANAGEMENT │
│ • Pain: Analgesia │
│ • Spasticity: Muscle relaxants │
│ • Bladder: As needed │
│ • Fatigue: Rest, pacing │
└─────────────────────────────────────────────────┘
↓
┌─────────────────────────────────────────────────┐
│ PREVENT FUTURE RELAPSES │
│ • Review DMT (disease-modifying therapy) │
│ • Ensure compliance │
│ • Consider switching DMT if frequent relapses │
│ • Lifestyle: Avoid triggers (infection, stress) │
└─────────────────────────────────────────────────┘
↓
┌─────────────────────────────────────────────────┐
│ MONITOR & FOLLOW-UP │
│ • Symptoms should improve within days to weeks │
│ • If not improving: Reassess │
│ • Long-term: DMT for prevention │
└─────────────────────────────────────────────────┘
Acute/Emergency Management - The First Hour
Immediate Actions (Do Simultaneously):
-
Check for Infection
- Urine dipstick: Check for UTI
- Other tests: As appropriate
- Action: Treat infection if present (may be pseudo-relapse)
-
Assess Severity
- Disability: How much function affected
- Function: Can patient function independently?
- Action: Determine if hospital admission needed
-
Start Steroids (If True Relapse)
- Methylprednisolone: High dose (500mg-1g IV or 500mg-1g oral)
- Mechanism: Reduces inflammation
- Duration: 3-5 days
-
Supportive Care
- Symptom management: Pain, spasticity, bladder
- Rest: Important for recovery
- Rehabilitation: As needed
Medical Management
High-Dose Steroids (First-Line):
| Drug | Dose | Route | Duration | Notes |
|---|---|---|---|---|
| Methylprednisolone | 500mg-1g | IV | OD | 3-5 days |
| Methylprednisolone | 500mg-1g | Oral | OD | 3-5 days (if IV not needed) |
Mechanism: Reduces inflammation → speeds recovery
Note: Steroids speed recovery but don't change long-term outcome or prevent future relapses
Symptom Management:
| Symptom | Treatment | Notes |
|---|---|---|
| Pain | Analgesia (paracetamol, NSAIDs) | As needed |
| Spasticity | Baclofen, tizanidine | If spasticity |
| Bladder | As needed | If bladder problems |
| Fatigue | Rest, pacing | Important |
Disease-Modifying Therapies (DMTs) - For Prevention:
| DMT | Type | Notes |
|---|---|---|
| Interferon beta | Injectable | First-line |
| Glatiramer | Injectable | First-line |
| Fingolimod | Oral | Second-line |
| Natalizumab | IV | Second-line |
| Ocrelizumab | IV | Second-line |
Mechanism: Prevents relapses, reduces inflammation
Note: DMTs prevent relapses but don't treat acute relapses
Disposition
Admit to Hospital If:
- Severe disability: Unable to function independently
- IV steroids needed: If severe or can't take oral
- Supportive care needed: Needs monitoring, rehabilitation
Outpatient Management:
- Mild-moderate cases: Can be managed outpatient
- Regular follow-up: Monitor recovery, DMT review
Discharge Criteria:
- Stable: No complications
- Can take oral: Oral intake OK
- Clear plan: For treatment, follow-up
Follow-Up:
- Symptoms: Should improve within days to weeks
- If not improving: Reassess, consider further investigation
- DMT review: Ensure on appropriate DMT, compliance
- Long-term: Ongoing MS management
Immediate (Days-Weeks)
| Complication | Incidence | Presentation | Management |
|---|---|---|---|
| Persistent symptoms | 20-30% | Symptoms don't fully recover | Ongoing management, rehabilitation |
| Infection (from steroids) | 5-10% | Increased infection risk | Treat infections |
| Steroid side effects | 10-20% | Insomnia, mood changes, GI upset | Usually self-limiting |
Persistent Symptoms:
- Mechanism: Incomplete recovery, permanent damage
- Management: Ongoing management, rehabilitation
- Prevention: Early treatment, prevent relapses
Early (Weeks-Months)
1. Further Relapses (If Not on DMT)
- Mechanism: Ongoing MS activity
- Management: DMT to prevent relapses
- Prevention: DMT compliance
2. Disability Accumulation
- Mechanism: Each relapse may cause some permanent damage
- Management: DMT to prevent relapses, rehabilitation
- Prevention: Prevent relapses with DMT
Late (Months-Years)
1. Secondary Progressive MS (20-30% over time)
- Mechanism: Relapses become less frequent, disability accumulates
- Management: Ongoing management, may need different DMT
- Prevention: Early DMT, prevent relapses
Natural History (Without Treatment)
Untreated MS Relapse:
- Most cases: Improve over weeks to months
- Some cases: May not fully recover
- Disability: May accumulate with each relapse
Outcomes with Treatment
| Variable | Outcome | Notes |
|---|---|---|
| Recovery | 70-80% | Most recover significantly |
| Persistent symptoms | 20-30% | Some symptoms may persist |
| Time to recovery | Days to weeks | With steroids |
| Mortality | Very low | Relapses themselves don't cause death |
Factors Affecting Outcomes:
Good Prognosis:
- Early treatment: Better outcomes
- Mild relapses: Usually recover well
- On DMT: Prevents future relapses
- Younger age: Better recovery
Poor Prognosis:
- Severe relapses: May not fully recover
- Not on DMT: Higher risk of further relapses
- Older age: May recover less well
- Multiple relapses: Disability accumulates
Prognostic Factors
| Factor | Impact on Prognosis | Evidence Level |
|---|---|---|
| Early treatment | Better recovery | High |
| Severity | More severe = worse | Moderate |
| DMT compliance | Prevents future relapses | High |
| Age | Younger = better recovery | Moderate |
Key Guidelines
1. NICE Guidelines (2019) — Multiple sclerosis in adults: management. National Institute for Health and Care Excellence
Key Recommendations:
- High-dose steroids for relapses
- DMTs for prevention
- Evidence Level: 1A
2. AAN Guidelines (2018) — Disease-modifying therapies for MS. American Academy of Neurology
Key Recommendations:
- DMTs for relapsing-remitting MS
- Evidence Level: 1A
Landmark Trials
Multiple studies on steroid treatment, DMT efficacy.
Evidence Strength
| Intervention | Level | Key Evidence | Clinical Recommendation |
|---|---|---|---|
| High-dose steroids | 1A | Multiple RCTs | First-line for relapses |
| DMTs | 1A | Multiple RCTs | Prevent relapses |
What is an MS Relapse?
An MS relapse (also called an exacerbation or flare) is a sudden worsening of neurological symptoms in someone with multiple sclerosis. It happens when new inflammation damages the protective covering around nerves (myelin), causing symptoms like weakness, numbness, vision problems, or balance issues. Think of MS as your nervous system's wiring—when MS flares, the insulation gets damaged, causing electrical signals to misfire.
In simple terms: Your MS symptoms suddenly get worse, usually lasting at least 24 hours. Most relapses improve with treatment, but some symptoms may persist.
Why does it matter?
MS relapses can cause significant disability and distress. Early treatment (steroids) can speed recovery and reduce disability. Preventing relapses with disease-modifying therapies (DMTs) is crucial for long-term outcomes. The good news? With proper treatment, most relapses improve significantly within days to weeks.
Think of it like this: It's like your MS symptoms flaring up—with the right treatment, they usually improve quickly.
How is it treated?
1. Check for Infection (Important):
- Why: Infections (especially UTIs) can make MS symptoms worse (pseudo-relapse)
- Treatment: If infection found, treat that first
- If symptoms persist: Then treat as true relapse
2. Steroid Treatment:
- High-dose steroids: Like methylprednisolone, reduce inflammation and help your symptoms recover faster
- Duration: Usually 3-5 days
- How to take: Usually IV in hospital if severe, or oral if mild-moderate
- Note: Steroids speed recovery but don't prevent future relapses
3. Symptom Management:
- Pain: Painkillers if needed
- Spasticity: Muscle relaxants if needed
- Bladder: As needed
- Fatigue: Rest, pacing
4. Prevent Future Relapses:
- DMTs: Disease-modifying therapies prevent relapses
- Compliance: Important to take DMTs as prescribed
- Lifestyle: Avoid triggers (infection, stress, heat)
The goal: Speed recovery from the relapse, manage symptoms, and prevent future relapses.
What to expect
Recovery:
- Most cases: Start feeling better within days
- Symptoms: Usually improve within days to weeks
- Full recovery: Most people recover significantly, but some symptoms may persist
After Treatment:
- Steroids: You'll take high-dose steroids for 3-5 days
- Symptoms: Should improve within days to weeks
- Follow-up: You'll need follow-up to monitor recovery and review your DMT
Recovery Time:
- Mild relapses: Usually recover within days to weeks
- Moderate relapses: Usually recover within weeks
- Severe relapses: May take longer, may not fully recover
When to seek help
See your doctor if:
- You have new or worsening MS symptoms lasting more than 24 hours
- You have symptoms that concern you
- You think you might be having a relapse
Call 999 (or your emergency number) immediately if:
- You have severe neurological symptoms (severe weakness, vision loss)
- You feel very unwell
- You have signs of infection (fever, urinary symptoms)
Remember: If you have new or worsening MS symptoms, especially if they last more than 24 hours, see your doctor. Early treatment can speed recovery and reduce disability. Also, always check for infection (especially UTIs) as infections can make MS symptoms worse.
Primary Guidelines
-
National Institute for Health and Care Excellence. Multiple sclerosis in adults: management. NICE guideline [NG220]. 2019.
-
Rae-Grant A, Day GS, Marrie RA, et al. Comprehensive systematic review summary: Disease-modifying therapies for adults with multiple sclerosis. Neurology. 2018;90(17):789-800. PMID: 29686116
Key Trials
- Multiple studies on steroid treatment and DMT efficacy.
Further Resources
- NICE Guidelines: National Institute for Health and Care Excellence
- MS Society: Multiple Sclerosis Society
Last Reviewed: 2025-12-25 | MedVellum Editorial Team
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists. This information is not a substitute for professional medical advice, diagnosis, or treatment.