Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare neurological disorder in which there is inflammation of nerve roots and peripheral nerves and destruction of the fatty protective covering (myelin sheath) over the nerves. This affects how fast the nerve signals are transmitted and leads to loss of nerve fibers. This causes weakness, paralysis and/or impairment in motor function, especially of the arms and legs (limbs). Sensory disturbance may also be present. The motor and sensory impairments usually affect both sides of the body (symmetrical), and the degree of severity and the course of disease may vary from case to case. Some affected individuals may follow a slow steady pattern of symptoms while others may have symptoms that stabilize and then relapse. CIDP is sometimes thought of as the chronic form of acute inflammatory demyelinating polyneuropathy (AIDP), the most common form of Guillain Barré syndrome (GBS), in the United States and Europe. In contrast to GBS, most patients with CIDP cannot identify a preceding viral or infectious illness. GBS is a subacute disorder that progresses over 3-4 weeks, then plateaus and usually improves over months and does not recur. CIDP, by definition has ongoing symptoms for over 8 weeks and usually does not improve unless ongoing treatment is given.