High-Resolution Ultrasound for Differentiation Between Leprosy-Associated Neuropathy and Vasculitic Peripheral Neuropathy: A Pilot Study.

INTRODUCTION/AIMS: Leprosy-associated neuropathy and vasculitic neuropathy (VN) share overlapping clinical features, making differentiation challenging in nonendemic regions. High-resolution ultrasound may aid in distinguishing these conditions, but comparative data are limited. This pilot study aimed to characterize and compare ultrasound findings in biopsy-confirmed leprosy-associated neuropathy and VN, and to identify distinctive sonographic features for early differential diagnosis.

METHODS

We retrospectively included 12 patients with biopsy-confirmed neuropathy (3 leprosy-associated, 6 systemic VN, 3 nonsystemic VN) from a prospectively maintained database at Peking Union Medical College Hospital (2020-2025). All had undergone standardized clinical assessments, nerve conduction studies, and high-resolution ultrasound of median, ulnar, tibial, fibular, and sural nerves, cervical roots, and brachial plexus. Cross-sectional areas (CSA) were measured at predetermined sites. Power Doppler assessed intraneural vascularization in enlarged segments.

RESULTS

In leprosy patients, nerve enlargement predominated proximal to entrapment sites (carpal tunnel, cubital tunnel/above-elbow, fibular head), with moderate-to-marked CSA increases. Intraneural power Doppler signals were detected in all enlarged segments (12/12, 100%). In VN patients, enlargement was mild-to-moderate, predominantly in nonentrapment regions (mid-forearm, upper arm), with less frequent vascularization (SVN: 25.0%; NSVN: 83.3%). Brachial plexus/cervical root enlargement was uncommon in both groups. Lower limb nerve enlargement occurred exclusively in leprosy.

DISCUSSION: Distinct ultrasound patterns may help distinguish leprosy-associated neuropathy from VN. Marked enlargement near entrapment sites with increased vascularization was more commonly observed in leprosy, while mild nonentrapment enlargement was more frequent in VN.