Imagine waking up tomorrow with a slight weakness in your feet. By around ten o'clock you can't move your legs. By early afternoon on the following day, you can't move your body or your arms. In another 24 hours, you start to find it difficult to breathe, speak or swallow, and by that evening you are on full life support in an intensive care unit, with a tube in your throat and a machine helping you to breathe.

The whole process of gradual paralysis may affect you more slowly. It may take two to three weeks to get to the life-support stage, but its progress is relentless. Whether it's fast or slower, all the time you remain fully conscious, knowing everything that is going on around you, yet unable to respond. Except that you can't close your eyes, and you hear the staff discussing whether it wouldn't be best to stitch your eyelids together, to prevent them drying out.

Think this is science fiction? A nightmare cooked up by some novelist? Not at all. The illness is called Guillain-Barre syndrome, or GBS. It hits all ages, but it peaks in the late teens and early twenties. Obviously, it's terrifying: most people with it assume they're dying. Yet they don't die. Because after some days or weeks of being artificially fed and breathing only with the aid of a machine, you start to recover.

First you can flicker your eyelids: then you can swallow and breathe again, then slowly all your muscles recover, in precisely the reverse order in which they were paralysed. You have every chance of a complete recovery, and of returning to your normal life.

How do you catch such an illness? Two-thirds of people who develop GBS have had an infection between one and three weeks beforehand. It may have been a chesty, flu-like illness, or gastro-enteritis. Researchers have picked out families of viruses (that produce, for example, pneumonia, chickenpox or glandular fever) and food poisoning bacteria as the main causes of the pre-GBS illnesses.

But these germs don't directly cause GBS. People who develop GBS are desperately unlucky. By coincidence, the chemicals their immune systems produce to kill off the germs also harm the normal "insulating system" around the nerves to their muscles. To work, muscles must receive electrical signals from the nerves leading to them from the brain.

Nerves are just like electric wiring. To keep the signal running along inside their length, they must be "insulated" against leaks. That is done by a covering of a fatty substance called myelin. Damage the myelin, and the nerve won't work, and the muscle it supplies is paralysed.

In GBS this is precisely what happens. The myelin around the nerves to the muscles is damaged. The longer nerves, with more insulation, are damaged first - the shorter nerves are affected later. That's why the paralysis starts in the feet, and ends in the shorter nerves near the brain.

And when the chemical attack is over (when the remnants of the infection are finally gone) the myelin starts to recover - first the shorter nerves (to the eyelids), then the rest follow, in their own time. As long as you can be kept alive until the healing process starts, you will recover.

Why am I writing about this now? Because we now have good treatments for GBS, provided they are started early enough. One is plasma exchange - in which the blood plasma (the fluid in which the red blood cells float) is replaced by donated plasma from people without the disease. It is a way of removing the offending chemicals from the blood. Given in the first few days it can stop the creeping paralysis in its tracks.

A second approach is with injections of a substance called IgG, or immune globulin, to give a more normal immune response. The two are equally effective. The researchers are now working hard on how to help the few GBS sufferers who are left with some paralysis.

GBS is only the tip of the iceberg of a host of nerve diseases. Success in tackling it is just the start. The next dominoes to fall in the battle against nerve diseases include multiple sclerosis, Parkinson's, Alzheimer's and motor neurone disease, all of which show some similarities to GBS.

Let's see what the next ten years of research can bring. If the progress against them is as good as that in GBS, we can all be quietly optimistic.

Converted for the new archive on 30 June 2000. Some images and formatting may have been lost in the conversion.