Guillain-Barre syndrome

What it is

Guillain-Barre syndrome is an acute immune-mediated polyneuropathy, written out as acute inflammatory demyelinating polyradiculoneuropathy, that typically manifests with bilateral ascending flaccid paralysis and sensory involvement such as paresthesia. Said another way, it is an acute, rapidly progressive demyelinating autoimmune disorder of the peripheral nerves that results in weakness. It is the most common polyneuropathy. Adults are affected more frequently than children.

The pathogenesis is a chain that is worth holding whole, because it explains both the delay and the treatment. An infection, typically Campylobacter jejuni, is taken up by an antigen-presenting cell, which acts on a B cell and then on a plasma cell, which makes cross-reactive antibody by molecular mimicry; the antibody, aimed at the organism, lands on the patient's own nerve instead. The antigens named are those in the myelin sheath, other Schwann-cell antigens, and axon membranes, and the result is immune-mediated segmental demyelination of the neuron of a peripheral or cranial nerve. Put shorter, the antibody attacks myelin.