The (mis)diagnosis of CIDP

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an immune-mediated peripheral nervous system disorder classically presenting with progressive, symmetrical limb weakness including the proximal muscles, generalized areflexia, and large fiber sensory loss.1 Electrodiagnostic studies show unequivocal segmental demyelination in multiple motor nerves or nerve roots, and the CSF protein level is usually elevated. In addition to classical CIDP, there are many variant presentations, so-called atypical forms, such as pure motor, pure sensory, regional (restricted to the upper or lower limbs), multifocal (Lewis-Sumner syndrome), and distal patterns.2 The diagnosis of CIDP can be established when patients meet carefully delineated clinical, electrodiagnostic, and laboratory criteria,1,2 but may be more challenging in cases with atypical presentations. Further difficulties arise when nerve conduction studies are inadequately performed or trivial nerve conduction abnormalities are labeled demyelinating. Misdiagnosis of CIDP leads to inappropriate and often long-term use of corticosteroids and IV immunoglobulin (IVIg), with the potential for adverse effects and an enormous financial burden to the health care system.