Guillain Barre syndrome - Disorders of Peripheral nerves

Guillain–Barre´ syndrome

Definition

An acute inflammatory polyradiculo-neuropathy characterised by progressive muscle weakness and areflexia.

Incidence

Although rare (∼1–2 per 100,000 population per annum), it is the commonest cause of acute flaccid paralysis in healthy people. It affects all ages and both sexes equally.

Aetiology/pathophysiology

Immune mediated demyelination of peripheral nerves typically 2–4 weeks after a mild respiratory or gastroin-testinal illness. It is thought that antibodies to the infecting organism crossreact with components of myelin. In particular, recent infection with Campylobacter jejuni is associated with a worse prognosis. Remyelination occurs over a period of 3–4 months and is associated with recovery in most cases.

Clinical features

Patients complain of distal paraesthesiae and numbness followed by weakness of distal limb muscles. This ascends over hours or days (up to 4 weeks) causing weakness, areflexia and sensory loss in the legs and arms, cranial nerve involvement with difficulty swallowing and respiratory muscle weakness in 20%. There may be backache or shooting pains down the back of the leg early in the course. Over the following weeks to months, the condition slowly improves.

Miller–Fischer syndrome, a clinical variant of Guillain–Barre´ syndrome, causes ophthalmoplegia, facial weakness, ataxia and areflexia.

Microscopy

Nerves show infiltration by lymphoid cells with phagocytosis of myelin by macrophages.

Complications

Respiratory insufficiency or aspiration risk (due to swallowing difficulties) may necessitate intubation and positive pressure ventilation. Autonomic involvement may occur at any stage, causing sweating, bladder dysfunction, hypo- or hypertension, arrhythmias and even sudden death by asystole.

Investigations

The diagnosis is essentially clinical but can be confirmed by EMG/ nerve conduction studies, which show slowing or blockage of conduction of nerve impulses. CSF analysis may be normal initially, but usually protein levels are high after the first week. Serial forced vital capacity (FVC) measurement is necessary to monitor respiratory muscle function. Oxygen saturations are of minimal value as they only fall late in respiratory failure.

Management

Patients should have cardiac monitoring and in some cases may be admitted to an intensive care unit, if ventilation is likely.

Intravenous immunoglobulin or plasma exchange reduces the duration and severity. They are generally used for moderate to severe cases (i.e. those who are unable to walk without assistance, or who require ventilation).

Prognosis

Recovery though gradual over many months is usual but is sometimes incomplete, leaving patients with distal neurological symptoms such as paraesthesiae or foot-drop. Mortality is∼5% despite intensive care. Prolonged (>2 months) of disability or recurrence should prompt the search for another cause.