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.
(See also Overview of the Peripheral Nervous System.)
Chronic inflammatory demyelinating polyneuropathy develops in 3 to 10% of people with Guillain-Barré syndrome. Like Guillain-Barré syndrome, it is a polyneuropathy. That is, it affects many peripheral nerves throughout the body
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
Most nerve fibers inside and outside the brain are wrapped with many layers of tissue composed of a fat (lipoprotein) called myelin. These layers form the myelin sheath, which function somewhat like the insulation around an electrical wire. The myelin sheath enables electrical impulses to be conducted along the nerve fiber much more rapidly.
When the myelin sheath is damaged, nerves do not conduct electrical impulses normally.
Symptoms of chronic inflammatory demyelinating polyneuropathy are similar to those of Guillain-Barré syndrome: Weakness is more prominent than 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.)
Symptoms may slowly worsen or may lessen or disappear, then worsen or reappear.
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.
- Electromyography, nerve conduction studies, and a spinal tap
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.
Electromyography, nerve conduction studies, and a spinal tap (lumbar puncture) to obtain cerebrospinal fluid (which surrounds the brain and spinal cord) are done to confirm the diagnosis.
Rarely, a biopsy of the nerve is needed to detect demyelination.
- Immune globulin
- Corticosteroids and/or drugs that inhibit the immune system
- Plasma exchange
Immune globulin (a solution containing many different antibodies collected from a group of donors) may be given by vein (intravenously) or under the skin (subcutaneously). It can relieve symptoms. It has fewer side effects than corticosteroids and is easier to use than plasma exchange (filtering of toxic substances, including antibodies to the myelin sheath, from the blood). However, after treatment is stopped, its beneficial effects may not last as long as those of corticosteroids.
Corticosteroids such as prednisone can relieve symptoms in some people with chronic inflammatory demyelinating polyneuropathy.
Drugs that inhibit the immune system (immunosuppressants) such as azathioprine may also be used.
If chronic inflammatory demyelinating polyneuropathy is severe or progresses rapidly or if immune globulin is ineffective, plasma exchange may be used.
People may need treatment for months or years.