Clinical and electroneuromyographic assessment in lepromatous leprosy: the confirmation of an asymmetrical and non-length-dependent pattern.

Background: Electroneuromyography (ENMG) is the gold standard test for evaluating neural impairment in leprosy. However, as it is a spectral disease and especially in advanced cases, the neurophysiological pattern is variable. It can be confused with numerous etiologies presenting a symmetrical polyneuropathy pattern. Objective: To describe electroneuromyographic findings in patients with lepromatous leprosy (LL). Methods: The study is a retrospective observational analysis of leprosy patients undergoing ENMG at a National Reference Center in Brazil. Results: 57 patients with LL underwent ENMG at diagnosis. On physical examination, all patients presented an asymmetrical distribution pattern of sensory symptoms, compatible with truncal and intradermal involvement in all cases. 89.5% had neural thickening, and 64.9% had motor symptoms. Concerning the ENMG findings, 417 altered nerves were identified, with an average of 7.9 (±4.2). 100% showed abnormalities in at least one sensory nerve, with an average of 5.5 (±2.3), and 89.0% in at least one motor nerve, with an average of 2.4 (±1.3). 3.6% had mononeuropathy, and 96.4% had multiple mononeuropathy, with asymmetry present in all cases. 100% presented sensory axonal impairment and 40.0% motor axonal impairment. 70.9% showed signs of demyelinating. The most commonly observed electroneuromyographic pattern was an axonal sensory-motor neuropathy, predominantly sensory, with focal myelin impairment in 61.9%. No patient presented a symmetrical neurophysiological pattern compatible with the diagnosis of polyneuropathy. Conclusion: The term polyneuropathy defines a diffuse, length-dependent, symmetrical involvement with distal predominance. Therefore, although confluent, the term polyneuropathy should not be used in this disease that presents an essentially asymmetrical involvement, even in LL.