What is CIDP?
Clearly the cut-off points used are somewhat arbitrary. The most common form of the disease is the chronic relapsing form with spontaneous improvement or remissions. About 80% of patients have this form of the disease. About 10% of patients have the subacute disease, which plateaus and then disappears spontaneously. Those with recurrent GBS form only a small percentage of CIDP patients.
Thus some people only have a single 'bout' of CIDP lasting for several months or years, after which a spontaneous recovery may be made. Others have many bouts in between which spontaneous remission and recovery occurs. After each bout the patient may be left with some residual numbness and weakness and sometimes discomfort. For many this will not seriously interfere with their lives, and they are able to continue with or resume their normal occupation. However a very small number are left severely disabled and may be dependent on a wheelchair or even bed bound. There is only a very unfortunate few for whom the disease continues to progress without remission.
What is going on?
The function of your brain is to interpret sensations and initiate movements and other responses. This activity depends on a complex communication system of nerves running to every part of your body via the spinal cord. Each nerve in this communication system can be compared to an electric cable. The inner part of the nerve, the axon, is made of conductive tissue and carries messages or impulses throughout your body - like the wires in an electric cable. The axon is surrounded by a layer of fatty substance, the myelin sheath, like the insulating cover on a cable. The myelin helps the conduction of messages along the nerves as well as insulating and protecting the nerve.
The symptoms of CIDP are due to inflammation and damage to the peripheral nerves and their roots. The peripheral nerves connect your central nervous system to your skin and muscle. CIDP is probably an autoimmune disease, ie one in which the immune system attacks its own body. The most likely mechanism is that the immune cells, called lymphocytes, somehow or other make a mistake and attack the nerves. The main part of the nerve that is attacked is the insulating sheath, or myelin.
The way in which the lymphocytes are tricked into attacking the body is still the subject of research. The lymphocytes may cause the formation of chemicals called antibodies that circulate in the blood and damage the myelin. Attempts to identify these antibodies have so far been only partially successful.
Fortunately the myelin sheath can be replaced within a few weeks or months by the myelin-forming cells named Schwann cells. If the nerve axons are damaged these can also re-grow, but this is much slower. Research is continuing into the underlying causes and mechanisms of the disease.
Although CIDP is a chronic condition with no known 'cure', several different treatments have been found to be helpful. They all act by suppressing the damaging autoimmune response. This in turn reduces the disabling symptoms of the disease. Examples are steroids, immunosuppressive drugs, plasma exchange and intravenous immunoglobulin.