Guillain-Barré Syndrome (GBS)
Guillain-Barré Syndrome (GBS) is a serious, acute, immune-mediated polyneuropathy of the peripheral nervous system. It’s characterised by progressive, symmetrical motor weakness and loss of reflexes (areflexia). GBS is a medical emergency in children due to the risk of respiratory failure, and prompt diagnosis and management are crucial.
Pathophysiology and Aetiology
Pathophysiology: GBS is triggered by an abnormal immune response, typically following an infection. The immune system produces antibodies that mistakenly attack the myelin sheath and axons of peripheral nerves. This demyelination slows nerve impulses, leading to the clinical symptoms.
Aetiology: Most cases follow an infection, most commonly Campylobacter jejuni, but also viruses like cytomegalovirus (CMV) and influenza. Less commonly, GBS can be triggered by a vaccination or surgery.
Clinical Presentation
Progressive Motor Weakness: The hallmark of GBS is a rapidly progressive, symmetrical weakness that usually starts in the legs and ascends to the arms, trunk, and face. The weakness can progress over days to weeks.
Areflexia: The loss of deep tendon reflexes is a key feature of GBS and is present in the affected limbs.
Sensory Symptoms: Children may report tingling or numbness (paraesthesia) in their hands and feet, or have back pain.
Cranial Nerve Palsies: Involvement of the cranial nerves is common, especially the facial nerve (CN VII), leading to bilateral facial weakness, and the glossopharyngeal and vagus nerves (CN IX, X), which can cause swallowing difficulties (dysphagia) and affect speech.
Respiratory Failure: Paralysis of the respiratory muscles is the most dangerous complication and occurs in about 20% of cases, requiring urgent ventilation.
Autonomic Dysfunction: Autonomic nerve involvement can cause heart rate and blood pressure instability.
Investigations
Cerebrospinal Fluid (CSF) Analysis: A lumbar puncture is a key investigation. In GBS, the CSF classically shows an “albuminocytological dissociation”—a very high protein level with a normal or only slightly elevated cell count.
Nerve Conduction Studies (NCS): These tests confirm the diagnosis by demonstrating demyelination, as evidenced by a reduced nerve conduction velocity.
Blood Tests: Blood tests are non-specific but may show a recent infectious trigger.
Management
Management focuses on reducing the immune response and providing intensive supportive care. The UK’s British Paediatric Neurology Association (BPNA) provides clear guidelines for the management of GBS.
Immediate Supportive Care:
Hospital Admission: All children with suspected GBS should be admitted to a high-dependency or paediatric intensive care unit for close monitoring.
Respiratory Monitoring: Monitor respiratory rate and oxygen saturation closely. A child with signs of bulbar weakness or a rapid progression of weakness should be intubated and ventilated early to prevent respiratory arrest.
Cardiovascular Monitoring: Monitor for signs of autonomic instability, such as hypertension or arrhythmias.
Immunomodulatory Therapy:
Intravenous Immunoglobulin (IVIG): This is the first-line treatment. IVIG is administered at a dose of 2 g/kg over 2-5 days. It has been shown to shorten the duration of the illness and accelerate recovery.
Plasmapheresis: This is an alternative treatment that removes harmful antibodies from the blood and can also be used, though it is less common in children.
Rehabilitation:
A multidisciplinary team including physiotherapists and occupational therapists is essential for long-term recovery, which can be a long process.
Prognosis
The prognosis for GBS is generally good. Most children make a full recovery, with about 50% recovering fully within 6 months and a majority within 12 months. However, about 10% may have some residual weakness. Relapse is rare, but some may develop a chronic form called Chronic Inflammatory Demyelinating Polyneuropathy (CIDP).