Leprosy neuropathy and demyelinating impairment: How should we interpret this neurophysiological pattern?

Area of Science:

• Neurology
• Infectious Diseases
• Clinical Electrophysiology

Background:

• Leprosy neuropathy (LN) involves nerve damage, potentially including demyelination, which can be exacerbated by leprosy reactions (LR).
• Understanding the specific patterns of nerve impairment, such as demyelination versus axonal degeneration, is crucial for accurate diagnosis and management of LN.

Purpose of the Study:

• To clarify and interpret the demyelinating patterns of nerve impairment in patients with leprosy neuropathy.
• To investigate the association between demyelination and leprosy reactions (Type-1 LR and Type-2 LR).

Main Methods:

• Retrospective observational analysis of leprosy patients.
• Evaluation of neurophysiological data from 3952 nerves across 494 participants over a 10-year period (2014-2023).

Main Results:

• A demyelinating pattern was observed in 23.5% of patients, with 20.7% showing exclusively demyelinating abnormalities.
• Conduction blocks (81%), temporal dispersion (95.7%), and prolonged distal motor latency (83.6%) were frequent findings.
• 93.1% of patients with demyelination met criteria for chronic inflammatory demyelinating polyneuropathy (CIDP), with 46.3% exhibiting atypical CIDP features.

Conclusions:

• Demyelinating nerve impairment is a frequent phenotype in leprosy neuropathy, varying with clinical form and leprosy reactions.
• While common, demyelination in LN does not necessarily indicate active disease.
• Leprosy neuropathy can be misdiagnosed as other peripheral neuropathies, particularly CIDP, especially in non-endemic regions.