Role of High-resolution Ultrasonography in the Evaluation of Ulnar Nerve Involvement in Patients with Leprosy

Abstract Background: Leprosy remains an important cause of peripheral neuropathy in endemic regions, with nerve involvement being the major determinant of long-term disability. The ulnar nerve is commonly affected. Conventional clinical assessment has limited ability to objectively quantify nerve damage. High-resolution ultrasonography (HRUS) enables structural evaluation of peripheral nerves in a non-invasive manner. Objective: The objective of the study was to assess ulnar nerve involvement using HRUS in patients with leprosy and to compare ultrasonographic findings with clinical examination. Materials and Methods: This prospective observational study was conducted at a tertiary care center from March 2024 to August 2025 and included 49 clinically diagnosed leprosy patients. All patients underwent clinical examination and HRUS of the ulnar nerve using a 12–18 MHz linear transducer. Cross-sectional area (CSA), fascicular pattern, echogenicity, and intraneural vascularity on power Doppler were evaluated. Results: The mean age was 43.86 ± 15.20 years, with male predominance (65.3%). Borderline tuberculoid (30.6%) and borderline lepromatous (26.5%) types were most frequent. HRUS detected ulnar nerve thickening in 89.8% of patients compared with 77.6% by clinical examination. Mean CSA was 11.90 ± 4.58 mm 2 . Loss of fascicular pattern was seen in 63.3%, altered echogenicity in 87.8%, and increased intraneural vascularity in 57.1%. HRUS showed sensitivity 93.6%, specificity 50.0%, positive predictive value 97.8%, negative predictive value 25.0%, and overall accuracy 91.8% for detecting ulnar nerve involvement. Conclusion: HRUS is a useful, noninvasive adjunct for objective detection and characterization of ulnar nerve involvement in leprosy and complements clinical assessment.