Guillain-Barre syndrome

Guillain–Barré syndrome (GBS) is a rapid-onset muscle weakness caused by the immune system damaging the peripheral nervous system. The initial symptoms are typically changes in sensation or pain along with muscle weakness, beginning in the feet and hands. This often spreads to the arms and upper body, with both sides being involved. The symptoms develop over hours to a few weeks. During the acute phase, the disorder can be life-threatening, with about 15% developing weakness of the breathing muscles requiring mechanical ventilation. Some are affected by changes in the function of the autonomic nervous system, which can lead to dangerous abnormalities in heart rate and blood pressure. The cause is unknown. The underlying mechanism involves an autoimmune disorder in which the body's immune system mistakenly attacks the peripheral nerves and damages their myelin insulation. Sometimes this immune dysfunction is triggered by an infection or, less commonly by surgery and rarely by vaccination. The diagnosis is usually made based on the signs and symptoms, through the exclusion of alternative causes, and supported by tests such as nerve conduction studies and examination of the cerebrospinal fluid. There are a number of subtypes based on the areas of weakness, results of nerve conduction studies and the presence of certain antibodies. It is classified as an acute polyneuropathy. In those with severe weakness, prompt treatment with intravenous immunoglobulins or plasmapheresis, together with supportive care, will lead to good recovery in the majority of people. Recovery may take weeks to years. About a third have some permanent weakness. Globally, death occurs in about 7.5% of those affected. Guillain–Barré syndrome is rare, at one or two cases per 100,000 people every year. Both sexes and all parts of the world have similar rates of disease. The syndrome is named after the French neurologists Georges Guillain and Jean Alexandre Barré, who described it with French physician André Strohl in 1916. The first symptoms of Guillain–Barré syndrome are numbness, tingling, and pain, alone or in combination. This is followed by weakness of the legs and arms that affects both sides equally and worsens over time. The weakness can take half a day to over two weeks to reach maximum severity, and then becomes steady. In one in five people, the weakness continues to progress for as long as four weeks. The muscles of the neck may also be affected, and about half experience involvement of the cranial nerves which supply the head and face; this may lead to weakness of the muscles of the face, swallowing difficulties and sometimes weakness of the eye muscles. In 8%, the weakness affects only the legs (paraplegia or paraparesis). Involvement of the muscles that control the bladder and anus is unusual. In total, about a third of people with Guillain–Barré syndrome continue to be able to walk. Once the weakness has stopped progressing, it persists at a stable level ('plateau phase') before improvement occurs. The plateau phase can take between two days and six months, but the most common duration is a week. Pain-related symptoms affect more than half, and include back pain, painful tingling, muscle pain and pain in the head and neck relating to irritation of the lining of the brain. Many people with Guillain–Barré syndrome have experienced the signs and symptoms of an infection in the 3–6 weeks prior to the onset of the neurological symptoms. This may consist of upper respiratory tract infection (rhinitis, sore throat) or diarrhea. In children, particularly those younger than six years old, the diagnosis can be difficult and the condition is often initially mistaken (sometimes for up to two weeks) for other causes of pains and difficulty walking, such as viral infections, or bone and joint problems. On neurological examination, characteristic features are the reduced strength of muscles and reduced or absent tendon reflexes (hyporeflexia or areflexia, respectively). However, a small proportion have normal reflexes in affected limbs before developing areflexia, and some may have exaggerated reflexes. In the Miller Fisher variant of Guillain–Barré syndrome (see below), a triad of weakness of the eye muscles, abnormalities in coordination, as well as absent reflexes can be found. The level of consciousness is normally unaffected in Guillain–Barré syndrome, but the Bickerstaff brainstem encephalitis subtype may feature drowsiness, sleepiness, or coma. A quarter of all people with Guillain–Barré syndrome develop weakness of the breathing muscles leading to respiratory failure, the inability to breathe adequately to maintain healthy levels of oxygen and/or carbon dioxide in the blood. This life-threatening scenario is complicated by other medical problems such as pneumonia, severe infections, blood clots in the lungs and bleeding in the digestive tract in 60% of those who require artificial ventilation.