Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) and Autoimmune Nodopathies (AN)
Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired inflammatory disorder in which the immune system attacks the myelin sheath of neurons in the peripheral nervous system (PNS), sometimes also involving the central nervous system (CNS) in rare cases of Combined Central and Peripheral Demyelination (CCPD).
Over time, this damage can lead to progressive weakness, tingling, numbness, and sensory loss, often beginning in the limbs. While the onset of CIDP can be insidious and is still poorly understood, some cases appear to be preceded by respiratory or gastrointestinal infections.
A subset of patients, now understood to represent a distinct clinical entity called autoimmune nodopathies (AN), as defined by the 2021 revised EAN/PNS guidelines, harbor IgG4 (and occasionally IgG3) autoantibodies against specific nodal and paranodal proteins such as neurofascin-140 (NF140), NF155, NF186, contactin-1 (CNTN1), and contactin-associated protein 1 (Caspr1). These proteins are critical for the formation and function of the Nodes of Ranvier, essential for rapid nerve signaling.
Though patients with AN may meet electrodiagnostic criteria for CIDP, their clinical course and treatment responses differ significantly; unlike typical CIDP, which often responds well to intravenous immunoglobulin (IVIg), AN cases generally do not, and instead show better outcomes with plasmapheresis or rituximab, an immunosuppressant that depletes B cells.
Monitoring autoantibody titers can be clinically useful, as they tend to correlate with disease activity. These distinctions underscore the importance of precise autoantibody testing for accurate diagnosis and targeted treatment, particularly in patients with atypical features or poor IVIg response.
The BC Neuroimmunology Lab (BCNI) is the first accredited North American lab to offer highly specific, validated fixed cell-based assays (CBAs) for detecting these autoantibodies, in collaboration with Dr. Luis Querol’s lab at San Pau Hospital in Barcelona. Additional confirmatory testing, including ELISA and nerve fiber studies, is also available upon request. Early detection remains crucial to prevent irreversible axonal damage.