Guillain-Barre Syndrome

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Guillain-Barre Syndrome

Guillain-Barre syndrome (GBS) is an acquired inflammatory, neurological disorder in which the immune system of the human body attacks portions of the body’s peripheral nervous system. The organization National Institute of Neurological Disorders and Stroke (NINDS) classifies GBS as a syndrome rather than as a disease because no known disease-causing agent is associated with GBS. Also called acute inflammatory demyelinating polyneuropathy, among other terms, it causes progressive muscle weakness and paralysis (complete inability to use a particular muscle or muscle group), which develops over days or up to four weeks, and lasts several weeks or even months. About 85% of patients recover completely, with no residual problems.

Causes

The classic scenario in GBS involves a patient who has just recovered from a typical, seemingly uncomplicated viral infection. The most common preceding infection is a herpes infection (caused by cytomegalo-virus or Epstein-Barr virus), although a gastrointestinal infection with the bacteria Campylobacter jejuni is also common. About 5% of GBS patients have a surgical procedure as a preceding event, and patients with lymphoma or systemic lupus erythematosus have a higher than normal risk of GBS. In 1976–1977, a hugely increased number of GBS cases occurred, with the victims all patients who had been recently vaccinated against the swine flu. The reason for this phenomenon has never been identified, and no other flu vaccine has caused such an increase in GBS cases. On average, in any given year, GBS affects about one to two people in every 100,000 people in the United States, a relatively rare rate. In 2006, that would relate to about 300 to 600 Americans. It is equally prevalent both genders, and in any age bracket.

The cause of the weakness and paralysis of GBS is demyelination of the nerve pathways. Myelin is an insulating substance that is wrapped around nerves in the body, serving to speed conduction of nervous impulses. Without myelin, nerve conduction slows or ceases. GBS is considered an acute inflammatory demyelinating pol-yneuropathy (acute: having a short, severe course; inflammatory: causing symptoms of inflammation; demyelinating: destructive of the myelin sheath; poly-neuropathy: disturbance of multiple nerves).

The basis for the demyelination is thought to be autoimmune (meaning that components of the patient’s own immune system go out of control, and direct themselves not against an invading virus or bacteria, but against parts of the body itself). Next to nothing is understood about why certain viruses, surgical events, or predisposing conditions cause a particular patient’s system to swing into autoimmune overdrive.

Symptoms

Symptoms of GBS begin five days to three weeks following the seemingly ordinary viral infection (or other preceding event), and consist originally of weakness of the limbs (legs first, then arms, then face), accompanied by prickly, tingling sensations (paresthesias). Symptoms are symmetric (affecting both sides of the body simultaneously), an important characteristic that helps distinguish GBS from other causes of weakness and paresthesias. Normal reflexes are first diminished, and then lost. The weakness ultimately affects all the voluntary muscles, eventually resulting in paralysis. Paralysis of the muscles of respiration necessitates mechanical ventilation, occurring about 30% of the time. Very severely ill GBS patients may have complications stemming from other nervous system abnormalities that result in problems with fluid balance in the body, and blood pressure and heart rhythm irregularities.

About 5% of all GBS patients die, most from cardiac rhythm disturbances. While the majority of patients recover fully, there are some patients (particularly children) who have some degree of residual weakness, or even permanent paralysis. About 10% of GBS patients begin to improve, and then suffer a relapse. These patients suffer chronic GBS symptoms.

Diagnosis

Diagnosis of GBS is made by virtue of the cluster of symptoms (ascending muscle weakness and then paralysis) and by examining the fluid that bathes the brain and spinal canal (cerebrospinal fluid or CSF). This fluid is obtained by inserting a needle into the lumbar (lower back) region. When examined in a laboratory, the CSF of a GBS patient will reveal an increased amount of protein over normal, with no increase over the normal amount of white blood cells usually present in CSF.

Treatment

Treatment of GBS is usually only supportive in nature, consisting of careful monitoring of the potential need for mechanical assistance in the event of paralysis of the muscles of respiration, as well as attention to the patient’s fluid and cardiovascular status.

Plasmapheresis, performed early in the course of GBS, has been shown to shorten the course and severity of GBS, and consists of withdrawing the patient’s blood, passing it through a cell separator, and returning all the cellular components (red and white blood cells, platelets) along with either donor plasma or a manufactured replacement solution. This action is thought to rid the blood of the substances that are attacking the patient’s myelin.

Recently, it has been shown that the use of high doses of immunoglobulin given intravenously (by drip

KEY TERMS

Autoimmune— Immune response in which lymphocytes mount an attack against normal body cells.

Inflammatory— Having to do with inflammation. Inflammation is the body’s response to either invading foreign substances (such as viruses or bacteria) or to direct injury of body tissue.

Myelin— The substance that is wrapped around nerves, and that is responsible for speed and efficiency of impulses traveling through those nerves. Demyelination is when this myelin sheath is disrupted, leaving bare nerve, and resulting in slowed travel of nerve impulses.

through a needle in a vein) may be just as helpful as plasmapheresis. Immunoglobulin is a substance naturally manufactured by the body’s immune system in response to various threats. It is interesting to note that corticosteroid medications (such as prednisone), often the mainstay of anti-autoimmune disease treatment, are not only unhelpful, but may in fact be harmful to patients with GBS.

Patients with certain characteristics tend to have a generally worse outcome from GBS. These include people of older age, those who required breathing support with a mechanical ventilator, and those who had their worst symptoms within the first seven days.