Guillain-Barre Syndrome is a frightening and disabling disease which strikes suddenly, sometimes with devastating effect.
The key symptom is the rapid onset of muscle weakness - and often, paralysis of the legs, arms, and even the muscles which control breathing. This means that in some cases, it can be fatal, although most patients will survive, and recover over time.
Approximately 1,000 patients a year develop the illness.
What causes it?
The cause of Guillain-Barré Syndrome is still unknown. However, as many as 60% of cases seem to arise shortly after an infection - which could be bacterial or viral. It is an autoimmune disease, in which the body's own defence mechanism, the immune system, malfunctions and attacks myolin, the material which covers and protects nerves. Damage to this lining stops nerve signals being transmitted effectively, leading to the muscle weakness or paralysis. In many ways, this damage is reminiscent of attacks in multiple sclerosis, where auto-immune inflammation damages the myolin, but unlike MS, there are unlikely to be any relapses.
There has been some suspicion among experts that immunisation may have some role in the disease - in particular, a jab against swine flu in the 1970s was anecdotally linked to an increase in incidence. However, there is little other scientific evidence to support the link with vaccines.
How is it diagnosed?
Guillain-Barré Syndrome normally manifests itself as tingling and numbness in the fingers and toes, followed by progressive weakness in the arms and legs. In some cases the weakness turns into paralysis of these limbs, and in a quarter of cases, the paralysis affects the chest and a patient will need a ventilator to breathe. Two tests will confirm the presence of the illness - a lumbar puncture to test the spinal fluid, and a test of the electrical activity reaching the muscles from the nerves.
What is the treatment?
Although patients with Guillain-Barré Syndrome will start to improve on their own, this can be helped by physiotherapy and other treatments. This include drugs and a procedure called plasmapheresis, in which the blood plasma is exchanged for a fresh supply. Most patients make a total recovery - although many have to spend extensive periods in hospital. Some do not recover completely and suffer from weakness or numbness. The time taken to recover is highly variable - sometimes it is only a week or two but most people remain affected for between three and six months.
One in 20 patients will die from the disease, and occasionally a patient will have a second attack.