Demyelinating Leprosy Neuropathy: An Unusual and Misleading Electrophysiological Pattern

Peripheral neuropathy, especially mononeuropathy multiplex, is a frequent manifestation of leprosy. Electrodiagnostic studies (EDX) usually show predominant axonal involvement. In this study, we report patients with prominent demyelinating abnormalities consistent with the diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).

We retrospectively reviewed the medical records of patients with leprosy who underwent EDX at Pitié-Salpêtrière University Hospital, Paris, France, between January 2014 and June 2022. We included patients exhibiting demyelinating abnormalities that fulfilled the 2021 European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) electrodiagnostic criteria for CIDP.

Ten patients were included. Eight patients presented with conduction blocks (CB) and temporal dispersion (TD) outside entrapment sites, primarily localized on the median and ulnar nerves in the forearm. Eight patients demonstrated delayed or absent F-waves in nerves without segmental slowing or CB/TD. Two patients were initially diagnosed with multifocal CIDP and treated accordingly before a nerve biopsy corrected the diagnosis. Follow-up EDX after anti-leprosy treatment revealed partial improvement or complete resolution of CB/TD in six patients, with improvement in distal motor amplitudes in four patients.

Patients with leprosy neuropathy can exhibit demyelinating abnormalities on EDX, particularly CB/TD in the forearm, which may misleadingly suggest an immune-mediated origin, such as multifocal CIDP. In patients from leprosy-endemic areas with a demyelinating neuropathy fulfilling electrodiagnostic criteria for CIDP, clinicians should perform a dermatological examination, repeat bacteriological and histological sampling, and consider performing a nerve biopsy if diagnostic doubt persists.