Median nerve impairment in leprosy: how does it differ from the classic carpal tunnel syndrome?

Abstract

Background Carpal tunnel syndrome (CTS) has already been described as a possible form of neural leprosy presentation. However, the median nerve can be involved in this neuropathy in proximal segments and, sometimes, with an asymmetric impairment of the digital branches.

Objective To detail the pattern of median nerve impairment through nerve conduction study (NCS) and ultrasound evaluation.

Methods This cross-sectional study comprises 15 primary neural leprosy (PNL) patients and 14 patients with CTS who underwent peripheral nerve ultrasonography and NCS evaluation.

Results From the total, 92.8% of patients with CTS and 80% with PNL had bilateral impairment of the median nerve, with 27 nerves in each group. Considering the cross-sectional area (CSA) of the tunnel (Mt) segment, 63% of the nerves in the CTS and 74.1% in the PNL groups were found to be thickened, with an average CSA of 13.4 ± 4.4 and 12.4 ± 4.6, respectively (p = 0.18). The CSA of the proximal tunnel (Mpt) segment showed thickening in only 3.7% in the CTS group and 96.3% in the PNL (p < 0.0001), with an average of 6.6 ± 1.3 and 17.0 ± 6.7, respectively (p < 0.001). Finally, 88.9% of the nerves in the PNL group and only 7.4% in the CSA (p < 0.0001) showed a reduction in conduction velocity in the distal forearm, with an average of 41.0 ± 6.3 and 53.2 ± 5.2, respectively (p < 0.0001).

Conclusion The presence of neural thickening and demyelinating impairment in the segments proximal to the carpal tunnel favors the diagnosis of leprosy.

Resumo

Antecedentes A síndrome do túnel do carpo (STC) já foi descrita como uma possível forma de apresentação da hanseníase neural. No entanto, o nervo mediano pode estar envolvido nesta neuropatia em segmentos proximais e, por vezes, com comprometimento assimétrico dos ramos digitais.

Objetivo Detalhar o padrão de comprometimento do nervo mediano através da avaliação eletroneuromiográfica e ultrassonográfica.

Métodos Este estudo transversal é composto por 15 pacientes com hanseníase neural primária (HNP) e 14 pacientes com STC que foram submetidos à avaliação ultrassonográfica e eletroneuromiográfica dos nervos periféricos.

Resultados Do total, 92,8% dos pacientes com STC e 80% com HNP apresentaram comprometimento bilateral do nervo mediano, com 27 nervos em cada grupo. Considerando a área de secção transversa (AST) do segmento do túnel (Mt), verificou-se que 63% dos nervos com STC e 74,1% com PNL estavam espessados, com AST média de 13,4 ± 4,4 e 12,4 ± 4,6, respetivamente (p = 0,18). A AST do segmento do túnel proximal (Mpt) apresentou espessamento em apenas 3,7% no grupo STC e 96,3% no grupo HNP (p < 0,0001), com uma média de 6,6 ± 1,3 e 17,0 ± 6,7, respetivamente (p < 0,001). Por fim, 88,9% dos nervos do grupo PNL e apenas 7,4% do AST (p < 0,0001) apresentaram redução da velocidade de condução no antebraço distal, com média de 41,0 ± 6,3 e 53,2 ± 5,2, respetivamente (p < 0,0001).

Conclusão A presença de espessamento neural e comprometimento desmielinizante nos segmentos proximais ao túnel do carpo favorece o diagnóstico de hanseníase.

Keywords

Leprosy - Peripheral Nerves - Ultrasonography - Mycobacterium leprae - Electromyography

Palavras-chave

Hanseníase - Nervos Periféricos - Ultrassonografia - Mycobacterium leprae - Eletromiografia

Authors' Contributions

PHSCA, FOC: conceptualization, data curation, formal analysis, investigation, methodology, project administration, supervision, validation, visualization, writing – original draft, writing – review and editing; LPG, JPMF: data curation, investigation, methodology, writing – original draft, writing – review and editing; ADML, DEA: conceptualization, data curation, formal analysis, investigation, methodology, project administration, supervision, validation, visualization, writing – original draft, writing – review and editing; RCP, WMJ: conceptualization, data curation, formal analysis, funding acquisition, investigation, methodology, project administration, supervision, validation, visualization, writing – original draft, writing – review and editing; IMBG: conceptualization, data curation, formal analysis, funding acquisition, investigation, methodology, project administration, resources, software, supervision, validation, visualization, writing – original draft, writing – review and editing; DFS: conceptualization, data curation, formal analysis, funding acquisition, investigation, methodology, project administration, resources, software, supervision, validation, visualization, writing – original draft, writing – review and editing. All authors approved the final version of the manuscript and agree to be responsible for all aspects of the work.

Editor-in-Chief: Hélio A. G. Teive.

Associate Editor: Francisco Gondim.

Publikationsverlauf

Eingereicht: 20. Juni 2024

Angenommen: 18. August 2024

Artikel online veröffentlicht:
10. Dezember 2024

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