Comparison of high resolution ultrasonography with clinical examination in the assessment of peripheral nerve involvement in leprosy

Abstract

Context: Assessment of peripheral nerves in leprosy by clinical methods is subject to considerable inter-observer variability. High resolution ultrasonography (HRUS) can assess peripheral nerves more objectively. Aims: To compare the findings of peripheral nerve involvement in newly diagnosed cases of leprosy by clinical and sonological methods. Settings and Design: Cross sectional study in a tertiary care teaching hospital. Subjects and Methods: Four pairs of peripheral nerves of 40 newly diagnosed patients with leprosy were examined clinically and by HRUS. Statistical Analysis Used: Agreement between clinical examination and HRUS using kappa statistic; sensitivity; specificity; and predictive values. Results: Of the 320 nerves examined, 71 (22.18%) were abnormal clinically and 63 (19.7%) sonologically. Sonological abnormalities were increased cross sectional area (n = 63; 100%), hypoechogenicity with loss of fascicular architecture (n = 46; 73%) and increased vascularity (n = 35; 55.6%). There was moderate agreement (Cohen’s Ḳ = 0.59) between clinical and sonological findings. HRUS findings were abnormal in 18 (7.2%) nerves that were clinically normal. HRUS was normal in 26 (36.6%) nerves which were clinically abnormal. Sensitivity of HRUS compared to clinical examination was 63%; specificity 92.7%; positive predictive value 71.4%; and negative predictive value 89.9%. Increased cross sectional area agreed with clinical findings the most. Conclusions: HRUS has low sensitivity (63%) and high specificity (92.7%) to identify abnormal peripheral nerves in leprosy, compared to clinical examination. It could detect abnormality of some (n = 18, 7.2%) clinically normal nerves, but showed normal findings of some nerves (n = 26, 36.6%), which were considered clinically abnormal.