Guillain-Barre syndrome

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

GBS is an acute immune-mediated polyradiculoneuropathy, often triggered by Campylobacter jejuni, a viral illness or another immune stimulus. Weakness commonly begins in legs and ascends, but arm, facial, bulbar or respiratory onset occurs. Reflexes are reduced or absent, though rare variants retain them. Sensory symptoms are usually milder than weakness; deep aching, radicular or neuropathic pain can be prominent. Miller Fisher syndrome features ophthalmoplegia, ataxia and areflexia, often associated with anti-GQ1b antibodies. Axonal variants cause reduced motor amplitudes and can recover more slowly. Diagnose clinically and do not wait for the classic CSF or neurophysiology pattern before admitting a progressing patient.

Respiratory surveillance is active, not observational. Ask about breathlessness lying flat, interrupted speech, weak cough, secretion clearance, dysphagia and morning headache. Serial forced vital capacity, maximal inspiratory and expiratory pressures or service equivalents reveal decline. A falling trend, bulbar dysfunction, rapid progression or autonomic instability warrants early critical-care involvement before an emergency intubation. Use a locally validated threshold; values around 20 mL/kg FVC are concerning, but clinical trajectory and bulbar protection matter and treatment must not wait for a single cut-off. Autonomic lability requires continuous ECG and close pressure monitoring, cautious fluid and vasoactive management and avoidance of provoking bradyarrhythmia.

IV immunoglobulin and plasma exchange have similar disease-modifying efficacy when given to appropriate patients early. A common IVIg course is total 2 g/kg divided over 5 days, adjusted by the commissioned immunoglobulin protocol, body-weight method, renal and thrombosis risk. Plasma exchange is an alternative when IVIg is unsuitable or according to availability and disease context. Routine sequential plasma exchange after IVIg does not add established benefit and may remove infused immunoglobulin. Corticosteroids alone are ineffective. Supportive care includes low-molecular-weight heparin when safe, swallowing and nutrition assessment, neuropathic and nociceptive pain control, bowel and bladder management, passive range and rehabilitation. Fatigue, pain and psychological effects can persist after power improves. Treatment-related fluctuation or progression beyond 8 weeks raises acute-onset CIDP and needs specialist reclassification.

Key points

Guillain–Barré syndrome usually causes rapidly progressive, relatively symmetrical limb weakness and areflexia reaching maximum severity within 4 weeks, often after respiratory or gastrointestinal infection.
Paraesthesia and severe back or radicular pain are common, but a clear sensory level, early bladder paralysis or persistent marked asymmetry suggests an alternative diagnosis.
Facial diplegia, dysphagia, weak neck flexion and inability to lift the head can precede respiratory failure and require frequent bedside reassessment.
Measure serial forced vital capacity and inspiratory strength where available; pulse oximetry and arterial gases may remain normal until respiratory muscle failure is advanced.
Autonomic involvement causes tachycardia, bradyarrhythmia, blood-pressure swings, ileus, urinary retention and sweating abnormalities and can be life-threatening.
CSF often shows raised protein with few cells after the first week, but can be normal early; substantial pleocytosis should redirect investigation towards infection or inflammation.
Nerve-conduction studies may show demyelination, conduction block or an axonal subtype and can also be non-diagnostic early, so repeat testing may be needed.
Treat non-ambulant or significantly progressive GBS with IV immunoglobulin or plasma exchange through specialist protocols; routine corticosteroids do not improve outcome.
Prevent venous thrombosis, pressure injury, contracture and aspiration, treat pain and provide rehabilitation and psychological support while axonal recovery evolves over months.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Post-infectious autoimmunity

GBS often follows respiratory or gastrointestinal infection, including Campylobacter-associated disease, through an immune response that cross-reacts with peripheral nerve targets.

Other immune triggers

Surgery and other immune events occasionally precede GBS, but temporal association alone does not establish causation and infection remains a common background exposure.

Antibody-defined variants

Different ganglioside targets contribute to demyelinating, axonal, Miller Fisher and regional phenotypes with differing eye, balance, bulbar and motor involvement.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Molecular mimicry
An immune response generated against a preceding antigen recognises similar glycolipid or nodal structures on peripheral nerves and roots.
2
Myelin or axonal injury
Antibodies, complement and inflammatory cells disrupt myelin, nodes or axolemma, producing conduction block and loss of motor or sensory signals.
3
Ascending and cranial spread
Multifocal nerve dysfunction commonly causes progressive limb weakness, areflexia, pain and facial or bulbar involvement over days.
4
Autonomic and respiratory failure
Involvement of autonomic fibres and respiratory motor nerves destabilises cardiovascular control, cough, swallowing and ventilation during rapidly progressive disease.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Ascending weaknessRed flag

Progressive bilateral leg then arm or cranial weakness with reduced reflexes over days strongly suggests GBS after cord compression and metabolic mimics are considered.

Bulbar and neck weaknessRed flag

Dysphagia, nasal speech, pooled secretions, weak cough or loss of head lift predicts aspiration and respiratory risk even before obvious breathlessness.

Autonomic instabilityRed flag

Large blood-pressure swings, resting tachycardia, episodic bradycardia, ileus or retention reflects dysautonomia and justifies monitored high-acuity care.

Miller Fisher syndromeRed flag

Ophthalmoplegia, sensory ataxia and areflexia with little limb weakness is a recognised GBS-spectrum variant requiring respiratory and bulbar vigilance.

Axonal variantRed flag

Profound motor weakness with low compound muscle action potentials and less slowing can represent acute motor axonal or motor-sensory axonal neuropathy.

Diagnostic mismatchRed flag

A sensory level, brisk reflexes, severe persistent asymmetry, early sphincter paralysis, fever or marked CSF pleocytosis should trigger investigation for cord, infection or another neuropathy.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Serial respiratory mechanicsFirst step
Why
Detect declining inspiratory, expiratory and cough strength before gas exchange fails.
Interpretation and limitations
Trend FVC and pressure measures with bulbar function; low or rapidly falling values require critical-care action even when saturation is normal.
02
Lumbar puncture
Why
Support polyradiculoneuropathy and investigate infectious, inflammatory or malignant alternatives.
Interpretation and limitations
Raised protein with few cells may appear after the first week; normal early CSF does not exclude GBS, while substantial cells demand another explanation.
03
Nerve-conduction studies and EMG
Why
Confirm peripheral physiology, classify demyelinating or axonal subtype and identify a mimic.
Interpretation and limitations
Early distal or proximal abnormalities can be subtle; repeat testing is reasonable when the clinical syndrome is convincing but the first study is equivocal.
04
ECG and continuous autonomic observations
Why
Detect arrhythmia, blood-pressure lability and conduction disturbance during the unstable phase.
Interpretation and limitations
Even asymptomatic bradycardia or wide pressure variation may precede dangerous events; use monitored care and senior cardiovascular support.
05
MRI spine when localisation is uncertain
Why
Exclude cord compression, transverse myelitis, cauda equina or another structural cause of acute weakness.
Interpretation and limitations
Root enhancement can support GBS but is non-specific; a cord lesion or compressive anatomy changes treatment urgently.
06
Trigger and mimic blood studies
Why
Find electrolyte, porphyria, infection, HIV, Lyme or other context-specific alternatives without delaying acute treatment.
Interpretation and limitations
Routine antiganglioside testing is not required for classic GBS, but anti-GQ1b can support Miller Fisher syndrome in specialist practice.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Acute spinal cord disease

A sensory level, early bladder paralysis, extensor plantar responses or persistent asymmetry favours compression, infarction or myelitis and warrants urgent spinal imaging.

Myasthenia or botulism

Ocular-bulbar fatigability with preserved sensation suggests myasthenia, while descending paralysis with fixed pupils and constipation supports botulism.

CIDP

Continuing progression or relapse beyond the usual acute monophasic course raises acute-onset CIDP, particularly when repeated treatment dependence emerges.

Toxic, metabolic or porphyric paralysis

Electrolyte disturbance, toxin exposure, abdominal symptoms or preserved reflexes may identify a reversible systemic cause without inflammatory polyradiculoneuropathy.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01AdmissionAnticipate respiratory failureFirst stepProgressive bilateral weakness and areflexia raises possible GBS.

1AlternativeAdmit urgently, document time course and power, reflexes, cranial nerves, neck flexion, cough, swallowing, autonomic symptoms and an alternative central localisation.
2Measure FVC and inspiratory or expiratory strength promptly and serially, monitor ECG and blood pressure and obtain critical-care review for decline or bulbar weakness.
3Arrange CSF and neurophysiology without delaying treatment, adding spinal imaging and infection or metabolic tests when atypical features occur.
4Protect swallowing, secretions, pressure areas and venous circulation while a senior neurology team confirms the immune-treatment plan.

02Disease modificationChoose one effective immune therapyThe patient is unable to walk independently or has significant progression, bulbar or respiratory disease.

1Check weight basis, renal function, thrombosis, viscosity, IgA and prior reaction considerations before commissioned IVIg, or assess access and stability for plasma exchange.
2Deliver IVIg or plasma exchange under the specialist protocol and monitor fluid, renal, thrombotic, haemodynamic and access complications.
3Do not substitute corticosteroids or routinely combine sequential plasma exchange with IVIg in the expectation of extra benefit.
4Reassess progression daily and consider treatment-related fluctuation, axonal disease or acute-onset CIDP when weakness follows an unexpected course.

03RecoveryPrevent secondary injury and rebuild functionWeakness stabilises and nerve recovery becomes the major goal.

1Use graded physiotherapy, positioning, splints and occupational support while avoiding exhausting denervated muscle or causing contracture.
2Treat neuropathic pain, constipation, retention, sleep and mood and wean ventilation or feeding support using objective respiratory and swallowing review.
3Provide realistic counselling that recovery can continue for months and that fatigue or pain may outlast apparent motor improvement.
4Arrange rehabilitation and neurology follow-up with urgent return advice for renewed weakness, breathing, swallowing or autonomic symptoms.

Key medicines and prescribing safety2 treatments · regimens, roles and cautions

Modifies immune nerve injury and shortens recovery in appropriately selected non-ambulant or significantly progressive GBS.

Intravenous human immunoglobulin

A standard specialist course totals 2 g/kg, commonly 0.4 g/kg daily for 5 days, using the NHS commissioned weight and product protocol.

Review thrombosis, renal impairment, haemolysis, aseptic meningitis, fluid load, IgA-related reaction and live-vaccine timing; monitor infusion. Current NHS England criteria state that a second GBS course is ineffective and may cause harm.

Reduces venous thromboembolism risk during profound weakness and immobility alongside mechanical and mobilisation measures.

Low-molecular-weight heparin prophylaxis

Use the local immobility prophylaxis dose adjusted for body weight, renal function, bleeding risk and planned lumbar or vascular procedures.

Coordinate timing with lumbar puncture and central access, monitor platelets or bleeding when indicated and do not use when haemorrhagic risk outweighs benefit.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Respiratory failure

Diaphragmatic, neck and bulbar weakness can cause ventilatory collapse before hypoxaemia or subjective breathlessness, requiring serial objective monitoring.

Autonomic instability

Blood-pressure swings, tachyarrhythmia, bradyarrhythmia, ileus and urinary retention can be sudden, life-threatening and require continuous monitoring.

Aspiration and immobility injury

Dysphagia and paralysis promote pneumonia, venous thrombosis, pressure damage, contracture and severe neuropathic pain during severe paralysis.

Residual weakness and fatigue

Axonal loss may leave long-term foot drop, pain, reduced endurance and psychological distress despite eventual control of the acute immune process.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Trend forced vital capacity, inspiratory strength, cough, secretion handling, bulbar function and speech at a frequency matched to speed of progression.
Use continuous ECG and close blood-pressure monitoring during significant autonomic disease, recording ileus, bladder function and temperature regulation.
Chart limb, neck and facial power and reflexes consistently to identify nadir, treatment-related fluctuation and recovery.
During IVIg monitor infusion reactions, fluid balance, renal function, haemolysis and thrombosis; during exchange monitor access, pressure, calcium and coagulation.
Review swallowing, nutrition, skin, VTE prevention, pain, contracture, mood and rehabilitation goals daily during immobility.
After discharge reassess fatigue, neuropathic pain, walking, work, driving and recurrent weakness, escalating progression beyond the expected monophasic course.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Oxygen can stay normal

Respiratory muscle weakness causes underventilation late; saturation may look reassuring until reserve is exhausted, whereas serial mechanics reveal the decline earlier.

CSF lags the bedside

Albuminocytological dissociation often develops after the first week, so a normal early lumbar puncture should not delay treatment of a convincing syndrome.

Pain can precede paralysis

Severe lumbar, radicular or limb pain may be the earliest feature and can be mislabelled musculoskeletal before reflex and motor change emerges.

Autonomic treatment needs gentleness

Denervated cardiovascular reflexes can overreact to fluid or vasoactive drugs, so small titrated interventions and monitored senior care are safer.

Eight weeks changes the frame

Continued progression or repeated deterioration beyond the usual acute course raises acute-onset CIDP and may require a different maintenance strategy.

11Common pitfallsFrequent interpretation and management errors.

01
Reassuring from normal pulse oximetry while forced vital capacity, cough and bulbar function are deteriorating.
02
Waiting for raised CSF protein or classic demyelination before admitting and treating rapidly progressive clinical GBS.
03
Measuring limb power but not neck flexion, swallowing, secretion handling and autonomic instability.
04
Using corticosteroids as disease-modifying monotherapy despite lack of benefit in GBS.
05
Giving routine plasma exchange immediately after IVIg, potentially removing treatment without established additive benefit.
06
Mobilising or exercising aggressively without fatigue, pain, denervation and contracture-aware rehabilitation planning.