Guillain-Barre Syndrome

Synonym: acute inflammatory polyneuritis

This is disorder causing demyelination and axonal degeneration, resulting in acute, ascending and progressive neuropathy. It is characterised by weakness, paraesthesiae, and hyporeflexia. In severe cases, muscle weakness may lead to respiratory failure. Severe autonomic dysfunction may also occur.

Miller-Fisher syndrome (MFS) is a rare variant that presents with ataxia, ophthalmoplegia and areflexia. Ataxia is usually the predominant feature, with a milder element of sensory loss. Recovery usually occurs within 1-3 months.¹

This is the most common acute neuromuscular paralytic syndrome. The annual incidence of Guillain-Barré Syndrome is 1-2/100 000 population in the UK. There is an increased incidence in males. Peak ages are 15-35 years and 50-75 years.¹

Risk Factors

Two thirds of patients have a history of gastrointestinal or respiratory infection from 1-3 weeks prior to the onset of weakness. These infections include Campylobacter, Hepatitis B, Mycoplasma pneumoniae, Cytomegalovirus, Epstein-Barr virus, and HIV.²
Other risk factors include:

• Vaccinations - live and dead vaccines have been implicated³
• Malignancies: e.g. lymphomas, especially Hodgkin's disease⁴
• Pregnancy - incidence decreases during pregnancy but increases in the months after delivery¹

History

• Weakness In 60% of cases, onset occurs approximately three weeks after a viral illness. The condition usually presents with an ascending pattern of progressive symmetrical weakness, starting in the lower extremities. This reaches a level of maximum severity 2 weeks after initial onset of symptoms and usually stops progressing after 5 weeks. Facial weakness, dysphasia or dysarthria may develop.
• Pain Neuropathic pain may develop, particularly in the legs. Back pain may be another feature.
• Reflexes These may be reduced or absent.
• Sensory symptoms These can include paraesthesiae and sensory loss, starting in the lower extremities.
• Autonomic symptoms Involvement of the autonomic system may present with reduced sweating, reduced heat tolerance, paralytic ileus and urinary hesitancy.

Examination

The following features may be present:

• Hypotonia
• Demonstrable altered sensation or numbness
• Lack of deep tendon reflexes
• Facial weakness - may be asymmetrical
• Autonomic dysfunction - fluctuations of heart rate and arrhythmias, labile blood pressure and variable temperature
• Respiratory muscle paralysis

Other causes of acute paralysis include:

• Brain: stroke, brainstem compression, encephalitis
• Spinal cord: cord compression, poliomyelitis
• Peripheral nerve: vasculitis, toxins, porphyria
• Neuromuscular junction: myasthenia gravis, botulism
• Muscle: hypokalaemia

Diagnosis usually is made on clinical grounds. However, the following may be helpful:

• Electrolytes - Inappropriate antidiuretic hormone occurs in some patients, serum and urine osmolarity studies are indicated if it is suspected
• Lumbar puncture - Most patients have an elevated level of cerebrospinal fluid (CSF) protein, with no elevation in CSF cell counts. The rise in the CSF protein may not be seen until 1-2 weeks after the onset of weakness.
• Antibody screen - Antibodies to peripheral and central nerves may be present.
• Spirometry - Forced vital capacity is a major determinant on the need for admission to ICU and then the need for intubation.
• Nerve conduction studies - Measurable slowing of nerve conduction may take 2-3 weeks to develop. A decrease to less than 20% of predicted normal is associated with a poorer prognosis.
• ECG - Many different abnormalities may be seen, e.g. 2nd and 3rd degree AV block, T-wave abnormalities, ST depression, QRS widening, and a variety of rhythm disturbances.

• Plasma exchange - A Cochrane Review supported the use of plasma exchange.⁵
• Intravenous immunoglobulin - This was also examined in a Cochrane review and found to be as effective as plasma exchange. There was no benefit in combining the two treatments. Further work needs to be done on the use of immunoglobulin in mild disease and where the condition lasts more than two weeks. Both therapies have been shown to shorten recovery time by as much as 50%.^1,6
• Intravenous methylprednisolone - This has no benefit as monotherapy.⁷ Some evidence suggest that combination with intravenous immunoglobulin may speed recovery, but does not affect long-term outcome.
• Deep vein thrombosis (DVT) prophylaxis - DVT should be prevented with gradient compression stockings and subcutaneous low molecular weight heparin.
• Admission to the intensive-care unit - This may be necessary in 33% of patients who require intubation and assisted ventilation.⁸

Possible complications include:

• Persistent paralysis
• Respiratory failure requiring mechanical ventilation
• Hypotension or hypertension
• Thromboembolism, pneumonia, skin breakdown
• Cardiac arrhythmia
• Ileus
• Aspiration
• Urinary retention
• Psychiatric problems, e.g. depression, anxiety

With modern intensive care support, the outcome is excellent with complete recovery in over 80% of patients.⁹ In severe cases, there is a higher frequency of persistent neurological dysfunction but the majority of this group make a good functional recovery. Poor prognosis is associated with rapid progression of symptoms, advanced age and prolonged ventilation. Miller-Fisher patients who have antibody subtype GM1 may have poorer prognoses.¹

The mortality rate is approximately 10%.² Most mortality is due to severe autonomic instability or from the complications of prolonged intubation and paralysis.⁸