Medicine chapters
Guillain-Barre syndrome
The acute post-infectious immune polyneuropathy that causes rapidly ascending weakness with lost reflexes, its variants, the CSF and nerve conduction findings, and why vital capacity monitoring and IVIG or plasma exchange matter.
- GBS is an acute, monophasic, immune-mediated demyelinating polyradiculoneuropathy, often 1–3 weeks after Campylobacter or a viral infection, caused by molecular mimicry.
- It gives ascending symmetrical weakness, early loss of reflexes, mild sensory symptoms, back pain, facial weakness and autonomic instability; CSF shows high protein with a normal cell count.
- Monitor vital capacity (ventilate at about 10 mL/kg or less), prevent DVT, and give IVIG or plasma exchange early; steroids do not help.
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Overview
Guillain–Barré syndrome (GBS) is the commonest cause of acute flaccid paralysis in adults and in children after the decline of polio. It is an immune attack on peripheral nerves and nerve roots, usually set off by an infection a few weeks earlier.
Its classic name is acute inflammatory demyelinating polyradiculoneuropathy (AIDP). Kumar and Clark give an incidence of about 3 per 100 000 per year.
GBS matters because patients can stop breathing within days, yet most recover with good supportive care.
Aetiology and pathogenesis
- Weakness begins 1–3 weeks after an infection, often a mild one that may not be remembered.
- Triggers:
- Campylobacter jejuni gastroenteritis: the best-known trigger, linked to severe, axonal forms and slower recovery.
- Cytomegalovirus, Epstein–Barr virus, Mycoplasma, influenza, Zika, HIV seroconversion.
- Less often vaccination or surgery.
- Molecular mimicry: antibodies made against sugars on the microbe (lipo-oligosaccharide) cross-react with gangliosides on nerve membranes such as GM1 and GQ1b.
- In the commonest form (AIDP) the target is the myelin sheath and Schwann cell; in AMAN the axon itself is attacked.
GBS is monophasic: it does not normally recur. A neuropathy that keeps worsening for more than about 8 weeks or relapses is CIDP.
Clinical features
- Weakness: starts in the legs (distal), rises to the arms, trunk and face over days up to 4 weeks (Kumar describes progression over several days to 6 weeks). It is symmetrical and flaccid.
- Reflexes: reduced or absent early, almost always.
- Sensory: tingling in hands and feet is common, but objective sensory loss is mild compared with the weakness.
- Pain: low back pain and aching limbs are frequent early features.
- Cranial nerves: bilateral facial weakness is common; bulbar weakness causes swallowing difficulty.
- Respiratory muscles: weak in about one in five patients, who may need ventilation.
- Autonomic involvement: swings in blood pressure, tachycardia or bradycardia, arrhythmias, urinary retention, ileus, sweating changes. A cause of sudden death.
- Bladder and bowel are usually spared early; early prominent sphincter loss suggests a spinal cord lesion instead.
- The patient is alert with normal consciousness.
Reflexes disappear early, even while muscle strength is still fair. This is because demyelination of the large, fast fibres in the proximal nerve roots breaks up the timing of the reflex arc before it causes severe weakness.
A clear sensory level on the trunk, early sphincter loss or extensor plantars point to spinal cord compression or transverse myelitis, not GBS.
Variants
| Variant | Key features |
|---|---|
| AIDP (classic) | Demyelinating; commonest in Europe and North America |
| Acute motor axonal neuropathy (AMAN) | Purely motor, axonal; strongly linked to Campylobacter; more common in South and East Asia (including Pakistan) and in children; anti-GM1 antibodies |
| Acute motor and sensory axonal neuropathy (AMSAN) | Severe, slow and incomplete recovery |
| Miller Fisher syndrome | Triad of ophthalmoplegia, ataxia, areflexia; anti-GQ1b antibodies in about 90% |
| Pharyngeal–cervical–brachial and pure sensory forms | Rare |
Miller Fisher = "OAA": Ophthalmoplegia, Ataxia, Areflexia, with GQ1b ("Q" for the eye muscles).
Investigations
| Test | Finding |
|---|---|
| CSF (lumbar puncture) | Raised protein (often 1–3 g/L) with a normal cell count and normal glucose = albuminocytological dissociation. Protein may be normal in the first week |
| Nerve conduction studies | Demyelinating form: slowed conduction velocity, prolonged distal motor latency, conduction block, absent or delayed F waves. Axonal forms: small or absent responses |
| Vital capacity (spirometry) | Repeated several times a day; falling values show respiratory muscle failure |
| Anti-ganglioside antibodies | Anti-GQ1b in Miller Fisher; anti-GM1 in axonal forms |
| Stool culture / serology | Campylobacter, CMV, EBV |
| ECG and BP monitoring | Arrhythmias, autonomic swings |
| Electrolytes | Exclude hypokalaemia; GBS can cause hyponatraemia (SIADH) |
| MRI spine (if doubt) | Exclude cord compression; may show enhancing nerve roots |
Albuminocytological dissociation (high protein, normal cells) is the classic CSF finding. A clearly raised white cell count should make you think of HIV, polio, Lyme disease, lymphoma or another diagnosis.
Differential diagnosis of acute flaccid weakness
| Condition | Clues that separate it from GBS |
|---|---|
| Spinal cord compression / transverse myelitis | Sensory level, early bladder involvement, later upper motor neurone signs |
| Poliomyelitis | Fever, asymmetric weakness, no sensory symptoms, CSF has raised cells |
| Myasthenia gravis | Fatiguable weakness, ptosis and diplopia, reflexes preserved, no sensory signs |
| Botulism | Descending paralysis starting with eyes and bulbar muscles, fixed dilated pupils, normal CSF |
| Hypokalaemic periodic paralysis | Low potassium, rapid onset after a carbohydrate meal, quick recovery with potassium |
| Tick paralysis, organophosphate, diphtheria, porphyria | History of exposure, other systemic features |
| Critical illness neuropathy / myopathy | Develops in ICU with sepsis and multi-organ failure |
Management
Supportive care (the most important part)
- Admit to a unit with ICU access.
- Measure vital capacity (forced vital capacity) regularly. Oxygen saturation and blood gases change late, after the patient is already in danger.
- Elective intubation and ventilation when the vital capacity falls to about 10 mL/kg or less, or there is bulbar weakness with aspiration risk, or a rising PaCO2.
- DVT prevention: low-molecular-weight heparin and compression stockings.
- Cardiac monitoring for autonomic arrhythmias; careful use of drugs that affect BP.
- Pain relief (neuropathic pain is common), pressure area care, bowel and bladder care.
- Swallowing assessment; nasogastric feeding if bulbar weakness.
- Early physiotherapy to prevent contractures; psychological support.
The single best bedside test to follow respiratory function in GBS (and myasthenia) is serial vital capacity, not pulse oximetry.
Disease-modifying treatment
- Intravenous immunoglobulin (IVIG): given within the first 2 weeks of onset, it shortens the illness and reduces the severity of paralysis. Usually a 5-day course. Screen for IgA deficiency first, because IgA-deficient patients can have severe allergic reactions.
- Plasma exchange (plasmapheresis): equally effective; an alternative where IVIG is not suitable or affordable. Often used in Pakistan, as it can be cheaper.
- Giving both together adds no benefit.
- Corticosteroids do not help in GBS (oral or intravenous), unlike in CIDP.
Treatment is given to patients who cannot walk unaided, are getting worse, or have respiratory or bulbar involvement.
Steroids are useful in CIDP but not in GBS. Students often mix these up.
Prognosis
- Weakness reaches its worst within about 4 weeks, then plateaus and recovers slowly over weeks to months, sometimes years.
- Most patients walk again, but in Kumar and Clark about 30% are left with some disability and 5–8% die, mostly from respiratory failure, autonomic arrhythmias, pulmonary embolism or infection.
- Poor outcome is linked to: older age, preceding diarrhoea (Campylobacter), rapid onset, need for ventilation, and axonal damage (small motor responses) on nerve studies.
Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)
| Feature | GBS | CIDP |
|---|---|---|
| Onset | Acute; peak within 4 weeks | Slow; progresses for more than 8 weeks |
| Course | Monophasic | Progressive or relapsing |
| Preceding infection | Common | Uncommon |
| Respiratory and autonomic failure | Common | Rare |
| CSF protein | Raised | Raised |
| Steroids | Not effective | Effective |
| Other treatments | IVIG, plasma exchange | IVIG, plasma exchange, long-term immunosuppression |
Some CIDP cases have a serum paraprotein, so check protein electrophoresis.
Expect: the typical history of ascending symmetrical flaccid weakness with lost reflexes after diarrhoea or a respiratory infection; Campylobacter jejuni as the classic trigger and molecular mimicry as the mechanism; CSF albuminocytological dissociation (and that it may be normal in week one); nerve conduction findings; vital capacity as the key monitoring test and the 10 mL/kg threshold for ventilation; IVIG or plasma exchange as treatment with steroids not helpful; IgA deficiency before IVIG; Miller Fisher syndrome with anti-GQ1b; autonomic complications; and how to separate GBS from polio, botulism, myasthenia, hypokalaemia and cord compression.
Quick revision
- Acute, monophasic, immune demyelinating polyradiculoneuropathy, 1–3 weeks after infection.
- Campylobacter jejuni (worse, axonal), CMV, EBV; molecular mimicry with gangliosides.
- Ascending symmetrical flaccid weakness, early areflexia, mild sensory signs, back pain, facial palsy, autonomic swings.
- CSF: high protein, normal cells (may be normal in week one).
- Monitor vital capacity; ventilate at about 10 mL/kg or less; LMWH for DVT.
- IVIG within 2 weeks or plasma exchange; no steroids; check IgA before IVIG.
- Miller Fisher: ophthalmoplegia, ataxia, areflexia, anti-GQ1b.
- CIDP: over 8 weeks, relapsing, responds to steroids.
Written by The House Job from standard references (Kumar and Clark's Clinical Medicine).
FAQ
What is albuminocytological dissociation?
It means the CSF protein is raised while the white cell count is normal, the typical finding in Guillain–Barré syndrome, usually from the second week.
Why is oxygen saturation a poor way to monitor a patient with GBS?
Saturation stays normal until the respiratory muscles are near failure, while vital capacity falls earlier and warns that ventilation will soon be needed.
Are steroids used in Guillain–Barré syndrome?
No; studies have shown no benefit, and treatment is with intravenous immunoglobulin or plasma exchange plus supportive care.
Can GBS come back?
Classic GBS is a one-off illness; a relapsing or slowly progressive course over more than two months suggests CIDP instead.