Guillain-Barré Syndrome (GBS)
Summary
Guillain-Barré Syndrome (GBS) is an acute, post-infectious, immune-mediated polyneuropathy. It is the most common cause of acute flaccid paralysis worldwide (since Polio eradication). The classic presentation is progressive, symmetric, ascending muscle weakness accompanied by Areflexia. The underlying pathology is "Molecular Mimicry": antibodies generated against a pathogen cross-react with gangliosides on host peripheral nerves. While 85% recover, it carries a mortality of 3-5% due to respiratory failure and autonomic dysregulation. [1,2]
Key Facts
- The "Ascent": Weakness typically starts in the toes/legs and moves up to the arms and face over days to weeks. (Nadir is reached by 4 weeks).
- Respiratory Risk: 25% of patients will require mechanical ventilation. Pulse oximetry is a late sign of failure; Forced Vital Capacity (FVC) is the mandatory monitoring tool.
- Steroids: Unlike many autoimmune conditions, Corticosteroids (Prednisolone) have NO BENEFIT in GBS and may actually delay recovery. Do not use them.
Clinical Pearls
The diagnosis is in the Reflexes: If a patient has profound weakness but normal or brisk reflexes, it is NOT GBS. Think Spinal Cord Compression (emergency MRI spine) or Transverse Myelitis. GBS causes Areflexia early.
Single Breath Count: A quick bedside test for respiratory reserve. Ask the patient to take a deep breath and count to 50 aloud. If they cannot reach 15 (Single Breath Count < 15), their FVC is likely < 1L. Intubation is imminent.
Pain: Often overlooked. 50% of patients have severe neuropathic pain (deep ache/burning) in the back and limbs, preceding the weakness.
Demographics
- Incidence: 1-2 per 100,000 per year.
- Sex: Male > Female (1.5 : 1).
- Age: Bimodal (Young adults and Elderly), but can affect any age.
Triggers (Antecedent Infection)
- Infection occurs 1-4 weeks prior in 70% of cases.
- Campylobacter jejuni (30%): Most common. Associated with axonal variants (AMAN) and worse prognosis.
- Viral: Epstein-Barr Virus (EBV), Cytomegalovirus (CMV), Zika, Influenza.
- Vaccines: Very rare association with flu vaccine (1 in 1 million), outweighed by risk of GBS from actual flu.
Molecular Mimicry
- Infection: The body fights Campylobacter (which has surface lipo-oligosaccharides).
- Cross-reaction: These bacterial sugars resemble human Gangliosides (like GM1, GQ1b) found on the myelin sheath or the Node of Ranvier.
- Attack: Macrophages strip the myelin (segmental demyelination) or attack the axon directly.
- Result: Nerves cannot conduct signals -> Paralysis + Areflexia.
Variants
- AIDP: Acute Inflammatory Demyelinating Polyneuropathy (Classic demyelinating form - 90% in West).
- AMAN: Acute Motor Axonal Neuropathy (Axonal form - more common in Asia/China).
- Miller Fisher Syndrome: Anti-GQ1b antibodies. Triad of Ataxia, Ophthalmoplegia, Areflexia.
Motor
Sensory
Autonomic (The Killer)
- Gait: High steppage gait (foot drop) or unable to walk.
- Tone: Flaccid.
- Power: Reduced globally.
- Reflexes: Absent.
- Cranial Nerves: Facial weakness (Uni or Bilateral LMN VII), Bulbar palsy (swallowing difficulty).
Lumbar Puncture (CSF)
- Protein: Elevated (>0.55 g/L).
- Cells (WCC): Normal (less than 5 lymphocytes).
- Result: "Albuminocytologic Dissociation".
- Caveat: Protein may be normal in the first week. High cells suggests HIV, Lyme, or Polio.
Neurophysiology (NCS/EMG)
- Conduction Velocity: Slowed (less than 40m/s).
- Conduction Block: Drop in amplitude proximally.
- F-Waves: Prolonged or absent (early sign).
Respiratory
- Spirometry: FVC < 20 ml/kg or < 1.0L indicates need for ICU/Intubation.
- ABG: Type 2 Respiratory Failure (High CO2) is a late sign. Do not wait for it.
Management Algorithm
SUSPECTED GBS
(Ascending weakness, Areflexia)
↓
ADMIT TO NEUROLOGY / ICU
(Check FVC, Single Breath Count)
↓
┌─────────────┼─────────────┐
AMBULANT NON-AMBULANT RESPIRATORY
(Mild symptoms) (Can't walk) FAILURE
↓ ↓ ↓
OBSERVE TREATMENT INTUBATE
(Supportive) (IVIG/Plex) (ventilate)
↓
┌─────────┴─────────┐
IVIG PLEX
(0.4g/kg/d x5d) (5 sessions)
(Preferred) (Equivalent)
1. Immunotherapy (Start within 2 weeks)
- IV Immunoglobulin (IVIG):
- Dose: 2g/kg total (divided over 5 days).
- Mechanism: Saturates Fc receptors, neutralises autoantibodies.
- Pros: Ease of administration.
- Plasma Exchange (PLEX):
- Mechanism: Filters antibodies from blood.
- Efficacy: Equal to IVIG.
- Cons: Needs central line, albumin replacement.
- Note: Combining both has NO added benefit.
2. Respiratory Support
- Elective Intubation if:
- FVC < 15-20 ml/kg.
- Bulbar dysfunction (aspiration risk).
- PaCO2 rising.
- Tracheostomy often needed for slow wean.
3. Supportive
- VTE Prophylaxis: LMWH + Stockings (High risk).
- Analgesia: Gabapentin/Amitriptyline for neuropathic pain.
- Autonomic: Cardiac monitoring. Pacing for bradycardia.
- Respiratory Failure.
- Arrhythmias/Cardiac Arrest: Especially during tracheal suctioning (vagal stimulation).
- DVT/PE: Pulmonary Embolism is a leading cause of sudden death.
- Pressure Ulcers.
- Mortality: 3-5%.
- Recovery: 80% walk independently at 6 months.
- Relapse: 5% Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) - chronic form (>8 weeks).
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| GBS Guidelines | EAN / PNS (2021) | Diagnosis criteria. Use IVIG or PLEX. No Steroids. |
| IVIG | Dept of Health | Priority indication for Immunoglobulin supplies (Red list). |
Landmark Trials
1. Dutch GBS Study Group
- Compared IVIG vs Plasma Exchange. Found them to be equally effective. 2. Corticosteroid Trials
- Cochrane reviews consistently show no benefit of oral or IV steroids.
What is GBS?
It is a condition where the body's immune system gets confused. After fighting a cold or stomach bug, the immune system mistakenly attacks the nerves that control your muscles.
Why muscles are weak?
The nerves are like electrical wires enclosed in plastic insulation (myelin). The immune attack strips off this insulation, so the signals can't get through to the muscles.
Is it permanent?
Usually, no. The body can repair the insulation. However, this takes time - weeks to months.
What is the treatment?
We give you a treatment called IVIG (antibodies from healthy donors) to stop your immune system attacking your nerves. We also watch your breathing very closely. If your breathing muscles get tired, we might need to use a machine to help you breathe for a while.
Primary Sources
- Leonhard SE, et al. Diagnosis and management of Guillain-Barré syndrome in ten steps. Nat Rev Neurol. 2019;15:671-683. PMID: 31541214.
- Hughes RA, et al. Immunotherapy for Guillain-Barré syndrome: a systematic review. Brain. 2007.
- Cochrane Database Syst Rev. Corticosteroids for Guillain-Barré syndrome. 2016.
Common Exam Questions
- CSF: "Typical finding?"
- Answer: Albuminocytologic Dissociation (High protein, normal cells).
- Variants: "Triad of Miller Fisher Syndrome?"
- Answer: Ophthalmoplegia, Ataxia, Areflexia.
- Management: "Best monitoring parameter?"
- Answer: FVC (Forced Vital Capacity). Not Sats.
- Treatment: "Role of Prednisolone?"
- Answer: None. Contraindicated/Ineffective.
Viva Points
- Campylobacter & Prognosis: Why is it worse? It often causes the Axonal form (AMAN), where the wire itself is cut, not just the insulation stripped. Axonal regrowth is much slower and less complete than remyelination.
- Autonomic Storms: Fluctuations in BP and heart rate. Be careful with vasoactive drugs.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.