Guillain-Barre Syndrome
Guillain-Barré (ghee-yan bah-ray) syndrome (GBS) is a disorder in which the body’s immune system attacks part of the peripheral nervous system. The peripheral nervous system includes the cranial nerves (except the optic [eye] nerve), the spinal nerves, and the autonomic nervous system that governs involuntary actions. The central nervous system is the spinal cord and brain.
GBS includes several subtypes, the most common of which is a multifocal demyelinating disorder of the peripheral nerves referred to as an acute inflammatory demyelinating polyneuropathy (AIDP). Some cases of GBS are associated with a primarily motor axonal process (acute motor axonal neuropathy; AMAN) with axonal degeneration (axons are long, thin extensions of the nerve cells and carry nerve signals) and sparing of the myelin (the myelin is an electrically insulating phospholipid layer that surrounds the axons of many neurons). Other cases appear to involve both sensory and motor axons and such cases are termed acute motor and sensory axonal neuropathy (AMSAN). More than 90% of patients with GBS in Europe and North America have AIDP. AMAN occurs in less than 10% of persons with GBS in the western hemisphere but in more than 40% of those affected in China and Japan. The incidence of AMSAN is very low (less than 10% of that of AMAN). Miller Fisher syndrome (MFS) is another GBS variant that occurs in about 5% of people affected by GBS. It is characterized by opthalmoplegia (eye muscle weakness), areflexia (absence of reflexes), ataxia (the inability to coordinate voluntary muscular movements such as walking), and, in some cases, facial and bulbar palsy (affecting vital functions, like breathing, and swallowing or speech).
GBS can affect anybody. It can strike at any age; men may be more likely to develop GBS than women. Although this syndrome is rare (affecting about one to two persons in 100,000) it is the most common cause of acute neuromuscular paralysis in the world.
Where does Guillain-Barré Syndrome come from?
GBS often occurs a few days or weeks after a person has had symptoms of a respiratory or gastrointestinal viral or bacterial infection; in fact, two-thirds of affected individuals have had a preceding infection. Campylobacter jejuni, cytomegalovirus, Epstein-Barr virus, and Mycoplasma pneumoniae are commonly identified antecedent pathogens, although C. jejuni is the most common pathogen that elicits GBS. Occasionally surgery or vaccinations will trigger the syndrome. GBS is not contagious. It has been reported that GBS occurs more in men than in women and more often in the elderly. Seasonality has not been reported in developed countries like the United States (Church Potter & Kaneene, 2003).
No one yet knows why GBS strikes some people and not others. Nor does anyone know exactly what sets the disease in motion. What scientists do know is that the body’s immune system begins to attack the body itself, causing what is known as an autoimmune disease. Usually the cells of the immune system attack only foreign material and invading organisms.
In GBS, the immune system starts to destroy the myelin sheath that surrounds the axons of many peripheral nerves, or even the axons themselves. The myelin sheath surrounding the axon speeds up the transmission of nerve signals and allows the transmission of signals over long distances. In diseases in which these myelin sheaths are injured or degraded, the nerves cannot transmit signals efficiently. That is why the muscles begin to lose their ability to respond to commands from the brain that must be carried through the nerve network. The brain also receives fewer sensory signals from the rest of the body, resulting in an inability to feel textures, heat, pain, and other sensations. Alternately, the brain may receive inappropriate signals that result in tingling, “crawling-skin,” or painful sensations. Because the signals to and from the arms and legs must travel the longest distances, they are most vulnerable to interruption. Therefore, muscle weakness and tingling sensations usually first appear in the hands and feet and progress upwards.
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