Guillain–Barré Syndrome - Cause

Cause

All forms of Guillain–Barré syndrome are autoimmune diseases, due to an immune response to foreign antigens (such as infectious agents) that is mistargeted at host nerve tissues instead, a phenomenon called molecular mimicry. The targets of such immune attack are thought to be gangliosides, compounds naturally present in large quantities in human peripheral nerve tissues. The most common antecedent infection is the bacterium Campylobacter jejuni, followed by cytomegalovirus (CMV). However, 60% of cases do not have a known cause. Some cases may be triggered by the influenza virus, or by an immune reaction to the influenza virus. There was increased incidence of Guillain-Barré syndrome following influenza immunization during the 1976-1977 swine flu pandemic; however, epidemiological studies since then had demonstrated either an extremely small increased risk following immunization (under 1 additional case per million vaccinations) or no increased risk. More recently, scientists in Quebec found a slightly increased incidence of Guillain-Barré as a result of H1N1 vaccinations in 2009, concluding that the vaccine was associated with a small but significant risk of GBS. Authors continued to find that the benefits of the immunization outweigh risks.

The end result of this autoimmune attack on the peripheral nerves is damage to the myelin, the fatty insulating layer of the nerve, and a nerve conduction block, leading to muscle paralysis that may be accompanied by sensory or autonomic disturbances.

In mild cases, nerve axon (the long slender conducting portion of a nerve) function remains intact and recovery can be rapid if remyelination occurs. In severe cases, axonal damage occurs, and recovery depends on the regeneration of this important tissue. Approximately 80% of patients have myelin loss; in the remaining 20%, the pathological hallmark is axon loss.

Guillain–Barré, unlike disorders such as multiple sclerosis (MS) and Lou Gehrig's disease (ALS), is a peripheral nerve disorder and does not in general cause nerve damage to the brain or spinal cord.