Dados do Trabalho

Título

Ultrasound abnormalities of the median nerve in leprosy neuropathy and carpal tunnel syndrome: How to differentiate these conditions?

Resumo

Introduction: Leprosy is a chronic infectious disease caused by Mycobacterium leprae which primarily involves the nerves and the skin. Its clinical forms are defined by the host immune response and bacillary load, resulting in a wide clinical spectrum. Currently, nerve assessment in leprosy relies mainly on clinical evaluation and nerve conduction studies, but although neurophysiology provides detailed information about the dysfunction of affected nerves, it does not reveal anatomic changes, such as thickening and fascicular pattern changes. High-resolution ultrasonography (US) is an additional technique that permits the examination of multiple nerve trunks over a long course in a few minutes and is considered an accessible and reasonably precise method. Objective: This study aims to compare the sites of median nerve enlargement in patients with leprosy and carpal tunnel syndrome (CTS). Methods: During the year 2021, were included in this study 15 leprosy patients and 14 patients diagnosed with CST, totaling 27 nerves in each group. All patients underwent a multisegmental US session of the median nerves, performed by an expert radiologist. The median nerve was scanned at the carpal tunnel (Mt) and 4 cm above the carpal tunnel (Mpt). The measurements of the cross-sectional area (CSA) and morphological characteristics such as echogenicity and fascicular pattern were assessed at these two points. We also calculated the absolute difference between CSAs of the nerve in the Mt and Mpt (ΔMtpt = Mt - Mpt). Results: CSA of the median nerve was increased in leprosy (13.4; ±4.4) and CTS (12.4; ±4.6) nerves at the Mt, but with no significant difference. 100% (27/27) of the nerves with leprosy showed some morphological abnormality at the Mt point and only 40.7% (11/27) of the CTS group (p=0.0042). CSA was higher among nerves with leprosy (17.0; ±6.7) as compared to CTS (6.6; ±1.3) at Mpt (< 0.0001). 100% (27/27) of the nerves with leprosy showed some morphological abnormality at the Mpt point and none of the CTS group. The ΔMtpt in leprosy nerves was -3.6 (±6.5) and 5.7 (±4.0) in the CTS (p< 0.0001). A measure of the ΔMtpt ≥ 2.2 indicates the diagnosis of CTS with a sensitivity of 100% and specificity of 96.3%. Conclusion: Median nerve enlargement in leprosy using US seems to be more proximal than in carpal tunnel syndrome (CTS), which might be an important discriminating sign.

Palavras Chave

Ultrasonography, median nerve, leprosy, carpal tunnel syndrome