27th June 2023

Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) describes a collection of acute immune-mediated polyneuropathies usually triggered by a recent upper respiratory infection or gastroenteritis (especially in association with infection by Campylobacter jejuni). Vaccination within the previous 4 weeks also appears to be a common trigger. Typical clinical features include a symmetrical muscle weakness which gradually appears over the course of days to short weeks. On examination, flaccid weakness of the upper and lower limbs is easily identified, starting in the lower limbs and following a distal-to-proximal progression. Absent or greatly reduced deep tendon reflexes are also a frequent finding. Cranial nerve involvement, such as facial nerve palsies, oropharyngeal weakness and ophthalmoplegia, can also be seen. Autonomic symptoms such as arrhythmias, hypotension and respiratory muscle weakness are common complications which may require review by the critical care team and warrant close monitoring, such as regular forced vital capacity testing. The diagnosis of GBS is usually made clinically, however, it can be assisted by using nerve conduction studies or a lumbar puncture, which reveals high protein levels within the cerebrospinal fluid.

The most common form of the disease, acute inflammatory demyelinating polyneuropathy (AIDP), is associated with clinical and electrophysiological evidence of peripheral demyelination and lymphocytic infiltration of the sural nerve in biopsies. In these cases, a focal inflammatory response affecting the myelin sheath or myelin-producing Schwann cells causes the development of areas of demyelination along the peripheral nerves. This phenomenon leads to a slowing of the propagation of saltatory electrical signalling, which manifests as muscle weakness when a threshold is reached. Axonal loss is a phenomenon that can be observed in most forms of GBS but can also be a predominant feature in certain variants. The Miller-Fisher variant of GBS is characterised by the clinical triad of ataxia, ophthalmoplegia and areflexia, in association with the presence of antibodies against GQ1b.

Pharmacological treatment of GBS includes intravenous immunoglobulins for five days to patients within four weeks of symptom onset, or plasma exchange therapy as an alternative. Regular assessment of respiratory muscle function with forced vital capacity is important to identify early involvement of the respiratory muscles; respiratory deterioration often warrants admission to intensive care for consideration of intubation and ventilation.