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 Overview of the Peripheral Nervous System The peripheral nervous system refers to the parts of the nervous system that are outside the central nervous system, that is, those outside the brain and spinal cord. Thus, the peripheral nervous... read more .)
Chronic inflammatory demyelinating polyneuropathy develops in 3 to 10% of people with Guillain-Barré syndrome Guillain-Barré Syndrome (GBS) Guillain-Barré syndrome is a form of polyneuropathy causing muscle weakness, which usually worsens over a few days to weeks, then slowly improves or returns to normal on its own. With treatment... read more . Like Guillain-Barré syndrome, it is a polyneuropathy Polyneuropathy Polyneuropathy is the simultaneous malfunction of many peripheral nerves throughout the body. Infections, toxins, drugs, cancers, nutritional deficiencies, diabetes, autoimmune disorders, and... read more . That is, it affects many peripheral nerves Overview of the Peripheral Nervous System The peripheral nervous system refers to the parts of the nervous system that are outside the central nervous system, that is, those outside the brain and spinal cord. Thus, the peripheral nervous... read more throughout the body
As in Guillain-Barré syndrome, an autoimmune reaction Autoimmune Disorders An autoimmune disorder is a malfunction of the body's immune system that causes the body to attack its own tissues. What triggers an autoimmune disorder is not known. Symptoms vary depending... read more , 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. Much like the insulation around an electrical wire, the myelin sheath enables nerve signals (electrical impulses) to be conducted along the nerve fiber with speed and accuracy. When the myelin sheath is damaged (called demyelination), nerves do not conduct electrical impulses normally.
Symptoms of CIDP
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.
Diagnosis of CIDP
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 Electromyography and Nerve Conduction Studies Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Imaging tests commonly used to diagnose nervous system (neurologic) disorders... read more , and a spinal tap Spinal Tap Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Imaging tests commonly used to diagnose nervous system (neurologic) disorders... read more (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.
Treatment of CIDP
Corticosteroids and/or drugs that inhibit the immune system
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 Plateletpheresis (platelet donation) In addition to normal blood donation and transfusion, special procedures are sometimes used. In plateletpheresis, a donor gives only platelets rather than whole blood. Whole blood is drawn from... read more (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 Corticosteroids Rheumatoid arthritis is an inflammatory arthritis in which joints, usually including those of the hands and feet, are inflamed, resulting in swelling, pain, and often destruction of joints.... read more such as prednisone can relieve symptoms in some people with chronic inflammatory demyelinating polyneuropathy.
Drugs that inhibit the immune system (immunosuppressants Suppression of the Immune System Transplantation is the removal of living, functioning cells, tissues, or organs from the body and then their transfer back into the same body or into a different body. The most common type of... read more ) 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 Plateletpheresis (platelet donation) In addition to normal blood donation and transfusion, special procedures are sometimes used. In plateletpheresis, a donor gives only platelets rather than whole blood. Whole blood is drawn from... read more may be used.
People may need treatment for months or years.