Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)
(Chronic Acquired Demyelinating Polyneuropathy; Chronic Relapsing Polyneuropathy)
(See also Overview of the Peripheral Nervous System.)
Chronic inflammatory demyelinating polyneuropathy is a form of polyneuropathy that, like Guillain-Barré syndrome, causes increasing muscle weakness, but the weakness progresses for more than 8 weeks.
Chronic inflammatory demyelinating polyneuropathy is thought to be caused by an autoimmune reaction that damages the myelin sheath around nerves.
In this disorder, weakness worsens continually over a period of more than 8 weeks.
Electromyography, nerve conduction studies, and analysis of cerebrospinal fluid can help confirm the diagnosis.
Treatment may include corticosteroids, drugs that inhibit the immune system, and sometimes immune globulin and plasma exchange.
Chronic inflammatory demyelinating polyneuropathy develops in 3 to 10% of people with Guillain-Barré syndrome.
As in Guillain-Barré syndrome, an autoimmune reaction, is thought to be involved. The body's immune system attacks the myelin sheath, which surrounds the nerve and enables nerve impulses to travel quickly.
Insulating a Nerve Fiber
Symptoms of chronic inflammatory demyelinating polyneuropathy are similar to those of Guillain-Barré syndrome: Weakness and abnormal sensations (numbness and a pins-and-needles sensation). However, these symptoms worsen for more than 8 weeks. (In Guillain-Barré syndrome, weakness usually worsens over 3 or 4 weeks, then remains the same or starts to return to normal.)
Reflexes are usually absent.
In most people with this disorder, blood pressure fluctuates less, abnormal heart rhythms occur less often, and other internal functions are less impaired than in people with Guillain-Barré syndrome. Also, weakness may be more irregular, affecting the two sides of the body differently, and weakness may progress more slowly.
Doctors suspect chronic inflammatory demyelinating polyneuropathy based on symptoms. It can be distinguished from Guillain-Barré syndrome because it progresses for more than 8 weeks.
Rarely, a biopsy of the nerve is needed.
Corticosteroids such as prednisone can relieve symptoms in some people. Drugs that inhibit the immune system (immunosuppressants) such as azathioprine may also be used.
However, if chronic inflammatory demyelinating polyneuropathy is severe or progresses rapidly, plasma exchange (filtering of toxic substances, including antibodies to the myelin sheath, from the blood) or immune globulin (a solution containing many different antibodies collected from a group of donors) given intravenously are used. These treatments are often preferred to corticosteroids because corticosteroids have many side effects.
People may need treatment for months or years.