A-waves are associated with neuropathic pain in leprosy.

INTRODUCTION/AIMS: The A-wave is a late response related either to demyelination or early axonal regeneration. It may be helpful in the evaluation of some peripheral neuropathies. In leprosy, previous studies suggested that A-waves could be a neurophysiological marker of pain in patients during reactions. Herein we have attempted to further assess the profile and clinical correlates of A-waves by exploring a large leprosy cohort.

METHODS

Between 2015 and 2018, 63 patients with leprosy (47 men and 16 women) had A-waves in nerve conduction studies and were included in this study. We included patients regardless of whether they were experiencing leprosy reactions or not. We then compared clinical features in nerves with and without A-waves.

RESULTS

The mean age of study participants was 46.5 ± 12.3 years and most had borderline leprosy. From this cohort, we assessed separately 83 motor nerves that demonstrated A-waves (group A+ ) and 29 motor nerves that did not demonstrate A-waves (group A- ). Neuropathic pain (NP) was found in 66 of 83 nerves in group A+ , but only 5 of 29 in group A- (79.5 vs 17.2%, P < .001). In contrast, no significant between-group difference emerged regarding presence of reactions, sensory function (based on Semmes-Weinstein evaluations), or muscle strength. A-waves were found in nerves with neuropathic pain experiencing (39 of 66 = 59%) or not experiencing (27 of 66 = 41%) leprosy reactions.

DISCUSSION: These results show that A-waves are associated with neuropathic pain in leprosy patients, regardless of the nerves affected and the immune status (in reaction or not).