What is Guillain-Barré syndrome?
Guillain-Barré syndrome (GBS) is a rare, acute, immune-mediated disease of the nerve roots and peripheral nerves (polyradiculoneuropathy). It is a neurological emergency and the most common cause of non-poliovirus acute flaccid paralysis worldwide. The typical picture is a symmetric, ascending weakness that begins with distal paraesthesias and then spreads from the legs to the arms and cranial nerves.
The estimated global incidence is 1.1 to 1.8 per 100,000 person-years, and about 70% of cases follow an infection. Symptoms usually start about 10 days after the trigger, reach their worst point (the nadir) within 2 weeks, then plateau for 1 to 4 weeks before recovery begins. The disease is typically monophasic.
| Stage | What happens |
|---|---|
| Trigger | Infection or other trigger, usually about 10 days before weakness |
| Progression | Weakness worsens to a nadir within 2 weeks |
| Plateau | Stable for roughly 1 to 4 weeks |
| Recovery | More than 50% recover fully within 1 year; 77% walk independently at 6 months |
| Relapse | Under 5% recur; about 10% show treatment-related fluctuations |
What triggers GBS and how does it injure the nerve?
GBS is an antibody-mediated attack triggered by molecular mimicry: an infectious organism carries surface molecules resembling nerve components, so the antibodies it provokes cross-react with the patient's own nerves. The classic example is Campylobacter jejuni, the most common antecedent infection, whose lipo-oligosaccharides contain ganglioside-like moieties. This mimicry, producing anti-ganglioside antibodies, is best established in AMAN and Miller Fisher syndrome. In AIDP the targets are less clear; with Mycoplasma pneumoniae the cross-reacting antigen is galactocerebroside, a myelin glycolipid.
- Common triggers at seroconversion: Campylobacter jejuni, hepatitis E virus, cytomegalovirus, Mycoplasma pneumoniae, Epstein-Barr virus and HIV.
- Arboviruses: Zika, dengue, chikungunya and Japanese encephalitis virus.
- Vaccines: influenza vaccines are associated with a small increased risk (the 1976 swine-flu vaccine carried the highest relative risk, 4 to 7.6). Some adenovirus-vector COVID-19 vaccines showed a risk; mRNA vaccines did not. The consensus is that vaccination benefits outweigh the GBS risk.
- Other: immune checkpoint inhibitors can cause GBS-like disease, treated differently (see management).
What are the clinical features of classic GBS?
The classic sensorimotor form begins with lower back pain from nerve-root inflammation and distal paraesthesias, followed by symmetric weakness of proximal and distal muscles, usually ascending (legs before arms). Deep tendon reflexes are absent or reduced — areflexia is the rule. Weakness reaching the cranial and respiratory muscles is what makes it dangerous.
- Cranial nerves: facial weakness is commonest, then oropharyngeal (bulbar) and extra-ocular involvement. Facial palsy risks corneal ulceration; bulbar palsy risks aspiration.
- Respiratory failure: greatest risk with rapid progression, bulbar dysfunction and neck or hip-flexor weakness.
- Autonomic dysfunction: fluctuating blood pressure and heart rate, bowel and bladder disturbance. It can cause cardiovascular compromise.
- Pain (back, limb) and anxiety are common and under-treated.
- Recurrence occurs in fewer than 5%; about 10% have treatment-related fluctuations (up to 2 relapses within 8 weeks of starting therapy), which respond to repeating the treatment.
What are the variants of GBS?
| Variant | Key feature | Antibody / electrophysiology |
|---|---|---|
| AIDP (acute inflammatory demyelinating polyneuropathy) | Classic demyelinating form of GBS | Prolonged distal latency, conduction block, temporal dispersion, prolonged or absent F-waves |
| AMAN (acute motor axonal neuropathy) | Pure motor; reflexes may be preserved; severe disease | Anti-GM1 and anti-GD1a; low distal CMAP amplitude, normal latencies and velocities |
| AMSAN (acute motor-sensory axonal neuropathy) | Motor and sensory; frequent autonomic and cranial nerve involvement; severe | Anti-GM1 and anti-GD1a; low CMAP and SNAP amplitudes |
| Miller Fisher syndrome | Triad of ophthalmoplegia, ataxia, areflexia | Anti-GQ1b in 85–90% |
| Bickerstaff brainstem encephalitis | Miller Fisher features plus impaired consciousness or hyperreflexia | Anti-GQ1b and GT1a |
| Pharyngeal-cervical-brachial | Weakness of throat, neck and arms with sparing of legs | Anti-GT1a |
| Facial diplegia with paraesthesias | Bilateral facial weakness, nadir within 4 weeks | Areflexia or hyporeflexia |
| Pure sensory, paraparetic, acute autonomic neuropathy | Rare restricted forms | — |
How is GBS diagnosed — what does the CSF show?
GBS is diagnosed clinically (history, examination, course); investigations support the diagnosis and exclude mimics. The Brighton criteria define four levels of diagnostic certainty based on the clinical picture, CSF, nerve conduction studies and course.
CSF: albuminocytological dissociation — raised total protein with a normal cell count — is the most typical finding. It reflects increased blood-nerve barrier permeability at the proximal nerve roots. Protein may be normal in about half of patients in the first week and is raised in 70–90% by the end of the second week, so a normal early CSF does not exclude GBS. Mild pleocytosis (10–20 cells/mm³) occurs in about 5%; more than 50 cells/mm³ should raise suspicion of infection, inflammation or malignancy. IVIG itself can raise CSF protein and cells.
- Nerve conduction studies classify AIDP, AMAN and AMSAN and may be normal early; repeat in 1 to 3 weeks if needed. Prolonged F-wave latency or absent F-waves and H-reflexes reflect proximal root involvement. A sural-sparing pattern (normal sural sensory potentials despite abnormal upper-limb sensory responses) supports GBS.
- MRI of the spine may show enhancement or thickening of nerve roots or the cauda equina.
- Anti-ganglioside antibodies are not routinely recommended; the exception is anti-GQ1b, found in up to 90% of Miller Fisher syndrome.
How is GBS treated?
Supportive care is the mainstay. Consider ICU admission for dysautonomia, bulbar dysfunction, severe or rapidly worsening weakness (especially neck and hip flexors) or respiratory distress. Add early physiotherapy, occupational therapy, nutrition and speech-language support; also prevent DVT and pressure injuries, and treat pain.
| Treatment | Dose / detail | Notes |
|---|---|---|
| IVIG | 2 g/kg over 2 to 5 days | Generally preferred: better tolerated, easier to give. Adverse effects: infusion reactions, headache, aseptic meningitis, renal injury with sucrose products, thromboembolism, anaphylaxis in IgA deficiency. |
| Plasma exchange | 50 mL/kg plasma per session; 2 sessions (mild), 4 (moderate), at least 4 (severe) | Equally effective as IVIG. Avoid in autonomic instability. Complications: hypotension, sepsis, hypocalcaemia, access problems. |
| Corticosteroids | — | Trials show no benefit and possibly worse outcomes. Exception: checkpoint-inhibitor GBS (IVIG 0.4 g/kg/day for 5 days with steroids). |
- Neither treatment halts progression or repairs nerve damage; both shorten time to recovery, especially if started early.
- About 40% report no improvement after immunotherapy; repeating IVIG or combining IVIG with plasmapheresis has not been shown to help.
What are the complications and the prognosis?
Long-term outcomes are favourable. More than 50% recover fully within a year; after immunotherapy 77% walk independently at 6 months and 81% at 12 months. Axonal GBS may keep improving beyond a year, though some patients do not recover fully.
- Respiratory insufficiency and cardiovascular instability are the most critical complications.
- Immobility: contractures, pressure palsies and ulcers, deep vein thrombosis and pulmonary embolism, which, along with ARDS and infections, is among the commonest causes of death.
- Hospital-acquired: pneumonia, urinary infection, delirium.
- Bulbar and facial weakness: dysphagia, aspiration, corneal injury.
- Persistent fatigue, pain and weakness may remain after recovery.