Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired immunologic inflammatory disorder characterized by loss of myelin in the peripheral nerves. Patients present with progressive, symmetric proximal and distal weakness and loss of sensory function in the legs and arms with decreased or absent reflexes. Sensory symptoms include sensory ataxia and impaired vibratory and sharp sensation. Unusual subtypes may be purely motor or purely sensory.

CIDP can be progressive or relapsing. The precise onset of symptoms is often difficult to identify. Cranial nerves, respiratory function, and autonomic functions are relatively spared.

CIDP can occur at any age, although it is more common in older males.