Guillain-Barré syndrome
Definition of Guillain-Barré syndrome
Guillain-Barrè (ghee-yan bah-ray) syndrome is a disorder in which the body's immune
system attacks part of the peripheral nervous system. The first symptoms of this disorder
include varying degrees of weakness or tingling sensations in the legs. In many instances
the weakness and abnormal sensations spread to the arms and upper body. These symptoms can
increase in intensity until certain muscles cannot be used at all and, when severe, the
patient is almost totally paralyzed. In these cases the disorder is life threatening
– potentially interfering with breathing and, at times, with blood pressure or heart
rate – and is considered a medical emergency. Such a patient is often put on a
respirator to assist with breathing and is watched closely for problems such as an
abnormal heart beat, infections, blood clots, and high or low blood pressure. Most
patients, however, recover from even the most severe cases of Guillain-Barrè syndrome,
although some continue to have a certain degree of weakness.
Guillain-Barrè syndrome can affect anybody. It can strike at any age and both sexes
are equally prone to the disorder. The syndrome is rare, however, afflicting only about
one person in 100,000. Usually Guillain-Barrè occurs a few days or weeks after the
patient has had symptoms of a respiratory or gastrointestinal viral infection.
Occasionally surgery or vaccinations will trigger the syndrome. The disorder can develop
over the course of hours or days, or it may take up to 3 to 4 weeks. Most people reach the
stage of greatest weakness within the first 2 weeks after symptoms appear, and by the
third week of the illness 90 percent of all patients are at their weakest.
Description of Guillain-Barré syndrome
The classic scenario in GBS involves a patient who has just recovered from a typical,
seemingly uncomplicated viral infection. Symptoms of muscle weakness appear one to four
weeks later. The most common preceding infections are cytomegalovirus, herpes,
Epstein-Barr virus, and viral hepatitis. A gastrointestinal infection with the bacteria Campylobacter
jejuni is also common and may cause a severe type of GBS from which it is particularly
difficult to recover. About 5% of GBS patients have a surgical procedure as a preceding
event. Patients with lymphoma, systemic lupus erythematosus, or AIDS have a higher than
normal risk of GBS. Other GBS patients have recently received an immunization, while still
others have no known preceding event. In 1976-77, there was a vastly increased number of
GBS cases among people 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.
Causes & symptoms of Guillain-Barré syndrome
The cause of the weakness and paralysis of GBS is the loss of myelin, which is the
material that coats nerve cells (the loss of myelin is called demyelination). Myelin is an
insulating substance which is wrapped around nerves in the body, serving to speed
conduction of nerve impulses. Without myelin, nerve conduction slows or stops. GBS has a
short, severe course. It causes inflammation and destruction of the myelin sheath, and it
disturbs multiple nerves. Therefore, it is considered an acute inflammatory demyelinating
polyneuropathy.
The reason for the destruction of myelin in GBS is unknown, although it is thought that
the underlying problem is autoimmune in nature. An autoimmune disorder is one in which the
body's immune system, trained to fight against such foreign invaders as viruses and
bacteria, somehow becomes improperly programmed. The immune system becomes confused, and
is not able to distinguish between foreign invaders and the body itself. Elements of the
immune system are unleashed against areas of the body, resulting in damage and
destruction. For some reason, in the case of GBS, the myelin sheath appears to become a
target for the body's own immune system.
The first symptoms of GBS consist of muscle weakness (legs first, then arms, then
face), accompanied by prickly, tingling sensations (paresthesias). Symptoms affect both
sides of the body simultaneously, a characteristic that helps distinguish GBS from other
causes of weakness and paresthesias. Normal reflexes are first diminished, then lost. The
weakness eventually affects all the voluntary muscles, resulting in paralysis. When those
muscles necessary for breathing become paralyzed, the patient must be placed on a
mechanical ventilator which takes over the function of breathing. This occurs about 30% of
the time. Very severely ill GBS patients may have complications stemming from other
nervous system abnormalities which can result in problems with fluid balance in the body,
severely fluctuating blood pressure, and heart rhythm irregularities.
Diagnosis of Guillain-Barré syndrome
Diagnosis of GBS is made by looking for a particular cluster of symptoms (progressively
worse muscle weakness and then paralysis), and by examining the fluid that bathes the
brain and spinal canal through cerebrospinal fluid (CSF) analysis. This fluid is obtained
by inserting a needle into the lower back (lumbar region). When examined in a laboratory,
the CSF of a GBS patient will reveal a greater-than-normal quantity of protein, with
normal numbers of white blood cells and a normal amount of sugar. Electrodiagnostic
studies may show slowing or block of conduction in nerve endings in parts of the body
other than the brain. Minor abnormalities will be present in 90% of patients.
Treatment
There is no direct treatment for GBS. Instead, treatments are used that support the
patient with the disabilities caused by the disease. The progress of paralysis must be
carefully monitored, in order to provide mechanical assistance for breathing if it becomes
necessary. Careful attention must also be paid to the amount of fluid the patient is
taking in by drinking and eliminating by urinating. Blood pressure, heart rate, and heart
rhythm also must be monitored.
A procedure called plasmapheresis, performed early in the course of GBS, has been shown
to shorten the course and severity of GBS. Plasmapheresis consists of withdrawing the
patient's blood, passing it through an instrument that separates the different types of
blood cells, and returning all the cellular components (red and white blood cells and
platelets) along with either donor plasma or a manufactured replacement solution. This is
thought to rid the blood of the substances that are attacking the patient's myelin.
It has also been shown that the use of high doses of immunoglobulin given intravenously
(by drip 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.
Prognosis
About 85% of GBS patients make reasonably good recoveries. However, 30% of adult
patients, and a greater percentage of children, never fully regain their previous level of
muscle strength. Some of these patients suffer from residual weakness, others from
permanent paralysis. About 10% of GBS patients begin to improve, then suffer a relapse.
These patients suffer chronic GBS symptoms. About 5% of all GBS patients die, most from
cardiac rhythm disturbances.
Patients with certain characteristics tend to have a worse outcome. 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.
Prevention
Because so little is known about what causes GBS to develop, there are no known methods
of prevention. |
