Guillain-Barré syndrome

Guillain-Barré syndrome (GBS), is an acquired immune-mediated inflammatory disorder of the peripheral nervous system (i.e. not the brain or spinal cord). It is also called acute inflammatory demyelinating polyneuropathy, acute idiopathic polyradiculoneuritis, acute idiopathic polyneuritis, French Polio and Landry's ascending paralysis.

Overview
The pathologic hallmark of the disease is loss of myelin in peripheral nerves due to an acute and progressive inflammation of unknown cause. It is suggested that it is an autoimmune disease, in which the sufferer's immune system is triggered into damaging the nerve covering. There is some support for this in that half of all cases occur soon after a microbial infection or respiratory or gastrointestinal viral infection. Many cases developed in people who received the 1976 swine flu vaccine.

Peripheral nerves originate in the spinal cord and proceed to their target tissues (mainly muscle, skin and all internal organs). Their most proximal parts emerging from the spinal cord are called nerve roots and the inflammation in most (but not all) typical Guillain-Barré syndrome cases starts in these roots. Therefore, this condition is also referred to as acute polyradiculoneuritis.

Recent studies on the disease have demonstrated that approximately 80% of the patients have myelin loss, whereas, in the remaining 20%, the pathologic hallmark of the disease is indeed axon loss. The cases indicating the demyelinating form (AIDP) are called "acute motor and sensory axonal neuropathy" (AMSAN); the cases showing only motor symptoms (diffuse weakness) are called "acute motor axonal neuropathy" (AMAN). In a different and infrequent variant called Miller Fisher syndrome, patients develop ataxia, loss of tendon reflexes, and difficulty moving eye muscles but not weakness or sensory loss. All variants of Guillain-Barré syndrome are now supposed to be an autoimmune disease caused by antibodies against a variety of gangliosides found in abundant amounts in the peripheral nerve tissue.

Prevalence
GBS is a rare disease affecting about 1 to 2 people in every 100,000 annually. It does not discriminate with regard to the age or sex of sufferers. When diagnosed in young teenagers, it generally does not recur for many years, although when it does, it often does so in the fourth or fifth decade of life, long after the patients may have forgotten the details of the original episode.

Cause
About one half of patients have a history of preceding viral infection within two to four weeks prior to exhibiting the onset of Guillain-Barré syndrome. Guillain-Barré syndrome may also be associated with certain immunizations, recent surgery or trauma, pregnancy, Hodgkin's disease, chemo-therapy, and connective tissue diseases. The most frequently associated viral agents are cytomegalovirus (CMV), HIV, measles and herpes simplex virus. A bacterium called Campylobacter jejuni has recently been shown to be closely related with certain subtypes of the disease: the risk of developing Guillain-Barré syndrome following campylobacter infection is less than 2 per 10,000 in the following two months. On the other hand, about 25 to 30 percent of people diagnosed with Guillain-Barré syndrome have had a recent infection with the campylobacter bacterium.

Signs and symptoms
Extensive damage of myelin causes disturbances in peripheral nerve functions, which can be classified as motor (affecting the muscle), sensory (affecting the skin) or autonomic (affecting the internal organs). Therefore, patients usually show two or more of the following symptoms: weakness (often symmetrical, in ascending fashion, leading to respiratory failure in one-third of cases), decreased sensation (numbness, loss of position sense), severe fluctuations in blood pressure, irregularities of heart rate, constipation and incontinence. Additional symptoms may be blurred vision, difficulty moving facial muscles, difficulty swallowing, and drooling.

The symptoms are ascending weakness with abnormal sensations and then paralysis of the legs, arms, face and possibly breathing muscles. Miller-Fisher Syndrome, however, is a descending weakness, proceeding in the reverse order of the more common form of Guillain-Barré syndrome. Guillain-Barré syndrome is rarely fatal but there is no direct cure and recovery may need care in an intensive care unit and can take years (although people can recover in a few weeks as well).

Diagnosis
The diagnosis is established by electromyography examination, nerve conduction studies (NCS), and cerebrospinal fluid (CSF) examination. Electromyography and NCS show slowing of conduction velocities, indicating myelin loss; CSF examination reveals high protein content with usually normal or slightly elevated cell count, indicating severe nerve damage. These findings are usually prominent after the first week of the disease, so the clinical symptoms and findings are more valuable in the early stages.

Treatment
Supportive care with monitoring of all vital functions is the cornerstone of successful management. Of greatest concern is respiratory failure due to paralysis of the diaphragm. Early intubation should be considered in any patient with a vital capacity (VC) <20 ml/kg, a Negative Inspiratory Force (NIF) <-25 cmH2O, more than 30% decrease in either VC or NIF within 24 hours, rapid progression of disease, or autonomic instability.

Because the immune mechanisms play a role in pathogenesis, plasma exchange or intravenous immunoglobulins over a course of treatment lasting five days may improve the outcome, preventing the need for a ventilator to be used. The use of intravenous immunoglobulins is not without risk, occasionally causing hepatitis, or in rare cases, renal failure if used for longer than five days. Although corticosteroids may be used in treatment, they are no longer considered the drug of first choice in modern practice because they may occasionally worsen symptoms.

Following the acute phase, the patient may also need rehabilitation to regain lost functions. This treatment will focus on improving ADL (activities of daily living) functions such as brushing teeth, washing and getting dressed. Depending on the local structuring on health care, there will be established a team of different therapists and nurses according to the patients needs. An occupational therapist can offer equipment (such as wheel chair and cutlery) to help the patient achieve ADL independence. A physiotherapist would plan a progressive training programme, and guide the patient to correct, functional movement, avoiding harmful compensations which might have a negative effect in the long run. There would also be a doctor, nurse and perhaps a speech trainer involved, depending on the needs of the patient. This team contribute with their knowledge to guide the patient towards his goal, and it is important that all goals set by the separate team members are relevant for the patient's own priorities.

After rehabilitation the patient should be able to function in his own home and attend necessary training as needed.

Prognosis
Approximately 80% of patients have a complete recovery and about 5-10% recover with severe disability. However, this is a grave disease and despite all improvements in treatment and supportive care, the death rate among patients with this disease is still about 2-3% even in the best intensive care units. Worldwide, the death rate runs slightly higher (4%), mostly from a lack of availability of life support equipment during the lengthy plateau lasting 4 to 6 weeks when a ventilator is needed in the worse cases.

History
The disease was first described by the French physician Jean Landry in 1859. In 1916, Georges Guillain, Jean Alexandre Barré and Andre Strohl discovered the key diagnostic abnormality of increased spinal fluid protein production, but normal cell count.

A peer-reviewed study published in 2003, concluded that Franklin Delano Roosevelt's 1921 paralytic illness was probably Guillain-Barré syndrome, not polio as previously assumed. The Bayesian analysis in the study found that six of eight posterior probabilities favored a diagnosis of Guillain-Barré syndrome over poliomyelitis.