High-Resolution Ultrasound for Differentiation Between Leprosy-Associated Neuropathy and Vasculitic Peripheral...

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.

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.

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.

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.