Paediatrics chapters
Guillain-Barré syndrome and acute flaccid paralysis
The commonest cause of acute flaccid paralysis in children: post-infectious ascending weakness with areflexia and high CSF protein, its variants, how to tell it from polio and cord disease, and how to treat it.
- Guillain-Barré syndrome is a post-infectious autoimmune polyneuropathy (often after a respiratory infection or Campylobacter jejuni diarrhoea) and the commonest cause of acute flaccid paralysis in children.
- It causes symmetrical ascending weakness with areflexia, little sensory loss, possible autonomic instability and respiratory failure; CSF shows high protein with normal cells after the first week.
- Admit, monitor vital capacity, ventilate if needed, give IVIG (plasma exchange if it fails); most recover. Every child under 15 with AFP must be reported and two stool samples sent for poliovirus.
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Overview
Acute flaccid paralysis (AFP) means sudden onset of floppy (lower motor neuron type) weakness of one or more limbs. In children, the commonest cause is Guillain-Barré syndrome (GBS), an acquired, immune-mediated polyneuropathy that usually follows an infection. GBS is important because it can quickly paralyse the breathing and swallowing muscles and cause autonomic instability, yet with good supportive care and immunotherapy most children recover fully. In Pakistan every AFP case also matters for the polio eradication programme, so it must be reported and investigated for poliovirus.
Guillain-Barré syndrome
Epidemiology
- Annual incidence roughly 0.4 to 1.7 per 100,000; very rare under 1 year.
- Slight male excess (about 1.5 to 1).
- Not hereditary.
Aetiology
- Typically follows a respiratory or gastrointestinal infection by about 10 days to 2 weeks; the infection has usually settled before weakness starts.
- Campylobacter jejuni (diarrhoea) is linked with a more severe, axonal form.
- Mycoplasma and viruses: CMV, Epstein-Barr virus, hepatitis B, mumps, measles, enteroviruses, influenza.
- Rarely after some vaccines.
Pathophysiology
- Organism antigens resemble components of peripheral nerve myelin or axon (molecular mimicry), so the immune attack hits the nerves.
- Patchy inflammation and demyelination with macrophages and lymphocytes; macrophages strip myelin from Schwann cells, leaving bare axons and causing conduction block. Axons can also be damaged.
- Inflammation is worst in the proximal nerve roots where dorsal and ventral roots join; leakage of plasma proteins there gives the high CSF protein.
Major variants
| Variant | Key features |
|---|---|
| AIDP (acute inflammatory demyelinating polyneuropathy) | The classic, commonest form; demyelination |
| AMAN (acute motor axonal neuropathy) | Pure motor, axonal; linked to Campylobacter |
| AMSAN (acute motor and sensory axonal neuropathy) | Motor and sensory axonal; often severe |
| Miller Fisher syndrome | Ophthalmoplegia, ataxia, areflexia; little limb weakness; raised CSF protein; recovers |
Miller Fisher = "OAA": Ophthalmoplegia, Ataxia, Areflexia.
Clinical features
- Often begins with tingling or pain in the feet, hands, back or around the mouth, or as a gait disturbance; pain in the back or legs is common.
- Symmetrical, ascending flaccid weakness: legs, then trunk, arms and cranial nerves, often over days (Landry ascending paralysis); can progress over hours or over weeks.
- Areflexia: tendon reflexes are lost early, even where strength is still fair; distal reflexes go first. Plantar responses are normal (flexor).
- Sensory loss is mild compared with the dramatic weakness.
- Cranial nerves: facial palsy is the commonest; bulbar weakness affects swallowing and voice.
- Respiratory failure in a minority (about 10 to 20% need ventilation). Dysphagia, facial and shoulder weakness warn that breathing may soon fail.
- Autonomic dysfunction: tachycardia and other arrhythmias, high or low blood pressure, postural hypotension, urinary retention.
- Fever is not typical; if present, look for another diagnosis or secondary infection.
- Bladder and bowel are usually spared; persistent sphincter loss argues against GBS.
Stages
| Stage | Duration and events |
|---|---|
| Progressive | Days to a few weeks; most complications happen now |
| Plateau | A similar period of stable weakness |
| Recovery | Weeks to months; recovery usually begins 2 to 4 weeks after progression stops |
Diagnostic criteria (summary)
- Required: progressive weakness of more than one limb and areflexia or marked hyporeflexia.
- Strongly supportive: progression over days to a few weeks, relative symmetry, mild sensory signs, cranial nerve involvement, autonomic dysfunction, no fever at onset, raised CSF protein after a week, slowed conduction on nerve studies.
- Raise doubt: marked persistent asymmetry, bladder or bowel dysfunction at onset or persisting, more than 50 white cells per microlitre in CSF, a sharp sensory level.
Investigations
| Test | Finding |
|---|---|
| CSF | Albuminocytological dissociation: protein raised (often over twice the upper limit) with normal or few cells (lymphocytes); glucose normal; may be normal in the first week |
| Nerve conduction / EMG | Slowed conduction, conduction block, prolonged F waves, reduced motor amplitudes; denervation in axonal forms; slowing may appear later |
| MRI spine (with contrast) | Enhancement of nerve roots; excludes cord compression or transverse myelitis |
| Serum CK | Normal or mildly raised |
| Antiganglioside antibodies | Sometimes positive (especially Miller Fisher) |
| Bedside respiratory function | Vital capacity and negative inspiratory force, checked regularly (Akbar: at least 6-hourly early on) |
| Stool for poliovirus | Two samples, as for every AFP case |
A CSF with many white cells or neutrophils does not fit GBS; think of polio, infection or another cause.
Differential diagnosis of acute flaccid paralysis
| Condition | Distinguishing features |
|---|---|
| GBS | Symmetrical, ascending, areflexic; mild sensory signs; sphincters spared; CSF high protein, normal cells |
| Poliomyelitis | Fever and meningism, then asymmetric patchy paralysis of a limb, no sensory loss; CSF lymphocytes with mildly raised protein; unimmunised child; stool culture positive |
| Acute transverse myelitis / cord compression | Sensory level, early bladder and bowel loss, back pain or spinal tenderness; arms may be normal; MRI diagnostic |
| Traumatic neuritis | Nerve injury (for example after trauma); history of the injury, weakness limited to that nerve |
| Botulism | Descending paralysis, ptosis, dilated pupils, constipation, clear mind, no fever |
| Tick paralysis | GBS-like picture; search the scalp and hair for a tick; recovery after its removal |
| Myasthenia gravis | Fatigable ptosis and bulbar weakness; reflexes normal |
| Diphtheritic polyneuritis | Follows diphtheria; palatal and pharyngeal paralysis |
| Hypokalaemic periodic paralysis | Episodic weakness; low potassium |
| Toxic neuropathy | Organophosphates, heavy metals, vincristine |
Nelson's pointers for GBS rather than a cord lesion: bowel and bladder kept, arm reflexes lost, no sensory level, no spinal tenderness.
Management of GBS
Supportive care (mainstay)
- Admit every child in the early stage; ascending paralysis can involve breathing within a day. Moderate, severe or rapidly progressive cases go to intensive care.
- Monitor vital capacity, inspiratory force, oxygen saturation, heart rate, blood pressure and cardiac rhythm.
- Ventilation when vital capacity is falling fast, there is breathlessness or fatigue, blood gases deteriorate, secretions cannot be cleared, or autonomic instability is severe. Prolonged ventilation may need tracheostomy.
- Nutrition (tube feeding if bulbar), bowel and bladder care, frequent turning to prevent pressure sores, prevention of deep vein thrombosis, pain relief.
- Treat secondary infections; physiotherapy, occupational and speech therapy during recovery.
Specific (immune) treatment
| Treatment | Points |
|---|---|
| IVIG | First choice; efficacy similar to plasma exchange and simpler. Akbar gives 400 mg/kg/day for 5 days or 1 g/kg/day for 2 days. Indicated in a child unable to walk with rapid progression or bulbar weakness and threatened breathing. Side effects: headache, nausea; rare relapse |
| Plasma exchange | Removes antibodies; best within the first two weeks; costly and not risk-less; alternative if IVIG fails or in rapid progression |
| Corticosteroids | Results are not consistently good; not the standard first-line treatment |
Steroids are not the treatment of choice for GBS; the answer is IVIG (or plasma exchange).
Prognosis
- Most children recover; recovery begins within 2 to 3 weeks of the plateau. Bulbar function recovers first, the legs last, and tendon reflexes are usually the last to return.
- Around 80% regain normal function (Nelson: over 1 to 12 months); about 20% have mild to moderate residual weakness. Children do better than adults.
- Mortality is low (Akbar: about 3%). The commonest causes of death are autonomic disturbance (arrhythmia) and respiratory failure.
- Poor outcome is predicted by cranial nerve involvement, need for intubation and maximum disability at presentation.
Poliomyelitis in brief
- Enterovirus spread by the faecal-oral route; multiplies in the gut, then may invade anterior horn cells.
- Most infections are silent (90 to 95%); a few cause a minor febrile illness, aseptic meningitis or paralysis.
- Paralytic polio: fever, myalgia and meningism, then asymmetric flaccid paralysis, usually of a leg, without sensory loss; paralysis is usually complete by the time the fever settles. Bulbar polio causes most deaths.
- Diagnosis: stool viral culture is the test of choice.
- Management: bed rest, neutral positioning (sandbags), analgesia with hot packs, no intramuscular injections in the acute phase, airway care in bulbar disease, later physiotherapy.
- Vaccine-associated paralytic polio is a very rare effect of OPV.
AFP surveillance (polio eradication)
Every case of AFP in a child under 15 years must be reported, even if the doctor is sure it is not polio (for example GBS, transverse myelitis or traumatic neuritis). Park describes four steps:
- Find and report every AFP case promptly to the district immunisation or health officer.
- Collect and transport stool: two specimens at least 24 hours apart within 14 days of paralysis onset, kept cold (reverse cold chain, 4 to 8°C), reaching the laboratory within 72 hours.
- Isolate poliovirus in the laboratory and separate wild from vaccine-related virus.
- Map the virus genetically to trace its origin and plan immunisation.
Re-examine every AFP case 60 days after onset to look for paralysis that remains.
Surveillance quality indicators (Park):
| Indicator | Minimum standard |
|---|---|
| Non-polio AFP rate | At least 1 per 100,000 children under 15 each year (2 per 100,000 in endemic regions) |
| Adequate stool samples | At least 80% of AFP cases |
| Timely reporting | At least 80% of expected reports, including zero reports |
Pakistan runs AFP surveillance through its national polio eradication programme; reporting rules and targets can change, so follow the current national guidance.
The non-polio AFP rate shows whether surveillance is sensitive enough; GBS cases count towards it.
Expect: GBS as the commonest cause of AFP; post-infectious onset (Campylobacter, Mycoplasma, viruses); symmetrical ascending weakness with early areflexia and mild sensory signs; facial palsy as the commonest cranial nerve sign; autonomic instability; CSF high protein with normal cells; monitoring by vital capacity; IVIG as treatment of choice with plasma exchange as alternative and no role for routine steroids; Miller Fisher triad; features favouring cord disease (sensory level, early sphincter loss); polio as asymmetric, febrile AFP without sensory loss diagnosed by stool culture; and AFP surveillance in under-15s with two stool samples within 14 days and a non-polio AFP rate of at least 1 per 100,000.
Quick revision
- AFP: commonest cause in children is GBS.
- Post-infectious (Campylobacter: severe axonal form), autoimmune, demyelinating.
- Symmetrical ascending flaccid weakness, areflexia, mild sensory signs, facial palsy.
- Autonomic instability and respiratory failure are the dangers; monitor vital capacity.
- CSF: high protein, normal cells (after the first week).
- IVIG first choice; plasma exchange alternative; steroids not standard.
- Recovery: bulbar first, legs last, reflexes last; 80% recover; children better than adults.
- Miller Fisher: ophthalmoplegia, ataxia, areflexia.
- Polio: fever, asymmetric, no sensory loss, stool culture.
- AFP under 15: report; two stools 24 hours apart within 14 days; 60-day follow-up.
Written by The House Job from standard references (Basis of Paediatrics by Pervez Akbar; Nelson Essentials of Paediatrics; Park's Preventive and Social Medicine).
FAQ
Why is the CSF protein high but the cell count normal in GBS?
Inflammation at the nerve roots damages the blood-nerve barrier so plasma proteins leak into the CSF, but there is no infection of the meninges to draw in white cells.
Why report a child with GBS to the polio programme?
Polio cannot be excluded on clinical grounds alone, so every child under 15 with acute flaccid paralysis is reported and stool tested for poliovirus.
When does a child with GBS need ventilation?
When vital capacity falls quickly, the child becomes breathless or tired, blood gases worsen, secretions cannot be cleared, or there is severe autonomic instability.
How is polio told apart from GBS at the bedside?
Polio gives fever and asymmetric weakness without sensory loss, with lymphocytes in the CSF; GBS gives symmetrical ascending weakness with areflexia, mild sensory signs and high CSF protein with normal cells.