Peripheral Nerve Ultrasound Findings in Leprosy: A Scoping Review of Echogenicity, Cross-Sectional Area, and Vascularization Across 15 Studies.

BACKGROUND

Leprosy is a chronic granulomatous disease caused by Mycobacterium leprae and Mycobacterium lepromatosis, primarily affecting the skin and peripheral nerves. Neuropathy in leprosy can result in significant disability, making early detection crucial. Ultrasound offers a non-invasive method to detect neuropathy by assessing echogenicity, cross-sectional area (CSA), and peripheral nerve vascularity.

OBJECTIVE

This review aimed to map and synthesize diagnostic role of peripheral nerve ultrasound, focusing on echogenicity, cross-sectional area, and vascularization, in detecting leprosy-related neuropathy.

METHODS

This scoping review was conducted in accordance with the PRISMA-ScR guidelines and included 15 studies assessing echogenicity, CSA, and vascularity in leprosy patients (sample sizes ranging from 20-308 participants).

RESULTS

Ultrasound consistently identified nerve abnormalities across 15 studies, including hypoechogenicity and fascicular pattern loss (up to 72% of nerves), CSA enlargement, and Doppler vascularity (11-45%) correlating with active inflammation. Reported CSA cut-offs (10-50 mm2) yielded sensitivities of 63-90% and specificities of 67-100% across studies. Ultrasound demonstrated superior sensitivity over clinical palpation and nerve conduction studies for subclinical neuropathy detection.

CONCLUSION

This scoping review demonstrates ultrasound's utility for early leprosy-related neuropathy detection. Ultrasound shows superior sensitivity over clinical palpation for subclinical involvement, particularly valuable for household contacts and pure neural leprosy. However, methodological heterogeneity precludes definitive diagnostic thresholds. Future research should standardize protocols and validate ultrasound parameters to optimize clinical application and disability prevention in endemic regions.