High-resolution ultrasound in the assessment of peripheral nerves in leprosy: A comparative cross-sectional study.

BACKGROUND

Detection of peripheral nerve thickening and nerve function impairment is crucial in the diagnosis and the management of leprosy.

AIMS AND OBJECTIVES

(1) To document the cross-sectional area, echotexture and blood flow of peripheral nerves in healthy controls and leprosy cases using high-resolution ultrasound, (2) to compare the sensitivities of clinical examination and high-resolution ultrasound in detecting peripheral nerve thickening in leprosy.

METHODS

Peripheral nerves of 30 leprosy patients and 30 age- and sex-matched controls were evaluated clinically and by high-resolution ultrasound. When the cross-sectional area of a peripheral nerve on high-resolution ultrasound in a leprosy patient was more than the calculated upper bound of the 95% confidence interval for mean for that specific nerve in controls, that particular peripheral nerve was considered to be enlarged.

RESULTS

Cross-sectional areas more than 7.1 mm2 for the radial nerve, 8.17 mm2 for ulnar, 10.17 mm2 for median, 9.50 mm2 for lateral popliteal and 11.21mm2 for the posterior tibial nerve were considered as nerve thickening on high-resolution ultrasound. High-resolution ultrasound detected 141/300 (47%) nerves enlarged in contrast to the 60 (20%) diagnosed clinically by palpation (P < 0.001). Clinical examination identified thickening in 31/70 (44.3%) nerves in cases with impairment of nerve function and 29/230 (12.6%) in the absence of nerve function impairment. High-resolution ultrasound detected thickening in 50/70 (71.4%) nerves with impairment of function and in 91/230 (39.6%) nerves without any impairment of function.

LIMITATION

A single-centre study design was the major study limitation.

CONCLUSION

High-resolution ultrasound showed greater sensitivity than clinical examination in detecting peripheral nerve thickening in leprosy cases. High-resolution ultrasound, may therefore improve the sensitivity of the diagnostic criterion of peripheral nerve enlargement in the diagnosis and classification of leprosy.