The red flags of ulnar neuropathy in leprosy

Abstract

The diagnosis of pure neural leprosy is more challenging because patients share characteristics with other common pathologies, such as ulnar compression, which should be taken into consideration for differential diagnosis. In this study, we identify ulnar nerve conduction characteristics to aid in the differential diagnosis of ulnar neuropathy (UN) in leprosy and that of non-leprosy etiology. In addition, we include putative markers to better understand the inflammatory process that may occur in the nerve. Data were extracted from a database of people affected by leprosy (leprosy group) diagnosed with UN at leprosy diagnosis. A non-leprosy group of patients diagnosed with mechanical neuropathy (compressive, traumatic) was also included. Both groups were submitted to clinical, neurological, neurophysiological and immunological studies. Nerve enlargement and sensory impairment were significantly higher in leprosy patients than in patients with compressive UN. Bilateral impairment was significantly higher in the leprosy group than in the non-leprosy group. Leprosy reactions were associated to focal demyelinating lesions at the elbow and to temporal dispersion (TD). Clinical signs such as sensory impairment, nerve enlargement and bilateral ulnar nerve injury associated with eletrodiagnostic criteria such as demyelinating finds, specifically temporal dispersion, could be tools to help us decided on the best conduct in patients with elbow ulnar neuropathy and specifically decide if we should perform a nerve biopsy for diagnosis of pure neural leprosy.

Fig 1. Serum levels of TNF and IL-6 in patients affected by leprosy with ulnar neuropathy and conduction block (CB+, n = 8) and without conduction block (CB-, n = 8).

Patients with leprosy neuropathy and CB+ presented significantly increased levels of IL-6, in comparison with CB- patients (P = 0.002). Unpaired t test was performed. TNF levels were similar for both groups.

Fig 2. Serum levels of TNF and IL-6 in leprosy patients with conduction block (CB+) and without conduction block (CB-) that did not have reactional episodes or leprosy neuritis (n = 6).

For IL-6, CB+ was significantly higher in comparison with CB- (P = 0.0009). TNF levels were not statistically different (P = 0.30). Unpaired t test was performed.