What is chronic inflammatory demyelinating polyneuropathy?

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an autoimmune condition that damages the protective myelin coating of peripheral nerves (the nerves outside the brain and spinal cord). Without intact myelin, nerve signals travel slowly or unreliably. The classic features are progressive weakness in the arms and legs (typically symmetric), loss of sensation, sometimes tingling or pain, and reduced or absent reflexes. The progression is usually over weeks to months and can be relapsing or steadily progressive.

Why it is autoimmune. The immune system mistakenly attacks myelin in peripheral nerves and the cells that produce it. The specific molecular targets in CIDP are the focus of active research, and a subset of patients have identified autoantibodies; for most patients, the specific autoantibody driver is not pinpointed, but the autoimmune mechanism is well-established.

How it is diagnosed. Diagnosis typically combines clinical features (the pattern of weakness and sensory loss), electrodiagnostic testing (nerve conduction studies showing the pattern of demyelination), and supportive findings (elevated protein in cerebrospinal fluid, MRI changes in nerve roots, response to a trial of immunotherapy). Distinguishing CIDP from other neuropathies (diabetic, hereditary, others) is sometimes challenging and requires expertise.

The traditional therapy.

Intravenous immunoglobulin (IVIG): pooled antibodies from many donors, given as an infusion. IVIG is highly effective for many patients with CIDP. After induction, maintenance dosing is given every 2 to 4 weeks indefinitely in most patients. Subcutaneous immunoglobulin is an alternative delivery route that some patients can self-administer at home.

Corticosteroids: oral prednisone or pulse intravenous methylprednisolone. Effective for many patients, but long-term use is limited by steroid-related side effects.

Plasma exchange (plasmapheresis): a procedure that removes antibodies from the blood. Effective in selected patients but logistically demanding for ongoing use.

The new direction.

FcRn antagonists: medicines that reduce circulating IgG levels (including the pathogenic antibodies that drive CIDP). Efgartigimod has CIDP approval and is given as a subcutaneous injection or infusion at scheduled intervals. The proposition is targeted reduction of the antibodies driving the disease, with manageable side effects and potentially longer dosing intervals than IVIG. Follow-on FcRn antagonist programs in CIDP are in late-stage trials.

Other emerging therapy. Complement-targeted programs, B-cell-targeted programs, and additional mechanism approaches are in earlier-stage trials.

What to expect. With appropriate immune therapy, most patients with CIDP achieve substantial improvement and stabilisation. Long-term maintenance is the rule rather than the exception; the goal is to find the right combination of therapy that controls the disease while minimising treatment burden. The expanded therapy options in the past several years offer more flexibility in matching therapy to patient circumstance.