Guillain–Barré syndrome

Guillain–Barré syndrome (GBS) is a disorder in which the immune system attacks the peripheral nervous system, leading to muscle weakness that comes on quickly. The weakness usually affects both sides of the body equally. Early signs often include unusual sensations or pain, frequently in the back, along with muscle weakness that starts in the feet and hands and tends to move up into the arms and upper body. These symptoms can develop over a few hours to several weeks. In the acute phase, the condition can be life-threatening: about 15% of people develop weakness in the muscles needed for breathing and require a ventilator. Some people also experience problems with the autonomic nervous system, which can cause dangerous changes in heart rate and blood pressure.

The exact cause is unknown, but the underlying process is an autoimmune reaction where the immune system mistakenly damages the myelin insulation of peripheral nerves. This immune dysfunction is sometimes triggered by a viral infection, or less often by surgery or vaccination. Diagnosis is based on symptoms and by ruling out other causes, with support from nerve conduction studies and analysis of cerebrospinal fluid. There are several subtypes, defined by the pattern of weakness, nerve conduction results, and the presence of certain antibodies. GBS is classified as an acute polyneuropathy.

For those with severe weakness, prompt treatment with intravenous immunoglobulins or plasmapheresis, along with supportive care, leads to good recovery in most cases. Recovery can take weeks to years, and about a third of people are left with some permanent weakness. Worldwide, about 7.5% of patients die from the condition. GBS is rare, occurring in 1 or 2 people per 100,000 each year. The syndrome is named after French neurologists Georges Guillain and Jean Alexandre Barré, who, with French physician André Strohl, first described it in 1916.

**Signs and symptoms**

The first symptoms are numbness, tingling, and pain, either alone or together. This is followed by weakness in the legs and arms that affects both sides equally and gets worse over time. The weakness can reach its peak in half a day to over two weeks, then stabilizes. In one in five people, the weakness continues to worsen for up to four weeks. Neck muscles may also be affected, and about half of people have involvement of the cranial nerves that contr