Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired autoimmune disease of the peripheral nervous system characterized by progressive weakness and impaired sensory function in the legs and arms. The disorder is sometimes called chronic relapsing polyneuropathy (CRP) or chronic inflammatory demyelinating polyradiculoneuropathy (because it involves the nerve roots). CIDP is closely related to Guillain–Barré syndrome and it is considered the chronic counterpart of that acute disease. Its symptoms are also similar to progressive inflammatory neuropathy. It is one of several types of neuropathy. Types
Several variants have been reported. Specially important are:

An asymmetrical variant of CIDP is known as Lewis-Sumner Syndrome. or MADSAM (multifocal acquired demyelinating sensory and motor neuropathy)
A variant with CNS involvement named combined central and peripheral demyelination (CCPD)Currently there is one special variant in which the CNS is also affected. It is termed "combined central and peripheral demyelination" (CCPD) and is special because it belongs at the same time to the CDIP syndrome and to the multiple sclerosis spectrum. These cases seem to be related to the presence of anti-neurofascin autoantibodies. Causes
Chronic inflammatory demyelinating polyneuropathy (or polyradiculoneuropathy) is considered an autoimmune disorder destroying myelin, the protective covering of the nerves. Typical early symptoms are "tingling" (sort of electrified vibration or paresthesia) or numbness in the extremities, frequent (night) leg cramps, loss of reflexes (in knees), muscle fasciculations, "vibration" feelings, loss of balance, general muscle cramping and nerve pain.
These symptoms are usually progressive and may be intermittent.Autonomic system dysfunction can occur; in such a case, the patient would complain of orthostatic dizziness, problems breathing, eye, bowel, bladder  and cardiac problems. The patient may also present with a single cranial nerve or peripheral nerve dysfunction.On examination the patients may have weakness, and loss of deep tendon reflexes (rarely increased or normal). There may be atrophy (shrinkage) of muscles, fasciculations (twitching) and loss of sensation. Patients may have multi-focal motor neuropathy, as they have no sensory loss.Most experts consider the necessary duration of symptoms to be greater than 8 weeks for the diagnosis of CIDP to be made. Fatigue has been identified as common in CIDP patients, but it is unclear how much this is due to primary (due to the disease action on the body) or secondary effects (impacts on the whole person of being ill with CIDP). Tests
Typical diagnostic tests include:

Electrodiagnostics – electromyography (EMG) and nerve conduction study (NCS). In usual CIDP, the nerve conduction studies show demyelination. These findings include:a reduction in nerve conduction velocities;
the presence of conduction block or abnormal temporal dispersion in at least one motor nerve;
prolonged distal latencies in at least two nerves;
absent F waves or prolonged minimum F wave latencies in at least two motor nerves. (In some case EMG/NCV can be normal). Serum test to exclude other autoimmune diseases. Lumbar puncture and serum test for anti-ganglioside antibodies. These antibodies are present in the branch of CIDP diseases comprised by anti-GM1, anti-GD1a, and anti-GQ1b.