Abstract
BackgroundNeuropathic pain (NP) is one of the main complications of leprosy, and its management is challenging. Infrared thermography (IRT) has been shown to be effective in the evaluation of peripheral autonomic function resulting from microcirculation flow changes in painful syndromes. This study used IRT to map the skin temperature on the hands and feet of leprosy patients with NP.Methodology/Principal findingsThis cross-sectional study included 20 controls and 55 leprosy patients, distributed into 29 with NP (PWP) and 26 without NP (PNP). Thermal images of the hands and feet were captured with infrared camera and clinical evaluations were performed. Electroneuromyography (ENMG) was used as a complementary neurological exam. Instruments used for the NP diagnosis were visual analog pain scale (VAS), Douleur Neuropathic en 4 questions (DN4), and simplified neurological assessment protocol. The prevalence of NP was 52.7%. Pain intensity showed that 93.1% of patients with NP had moderate/severe pain. The most frequent DN4 items in individuals with NP were numbness (86.2%), tingling (86.2%) and electric shocks (82.7%). Reactional episodes type 1 were statistically significant in the PWP group. Approximately 81.3% of patients showed a predominance of multiple mononeuropathy in ENMG, 79.6% had sensory loss, and 81.4% showed some degree of disability. The average temperature in the patients’ hands and feet was slightly lower than in the controls, but without a significant difference. Compared to controls, all patients showed significant temperature asymmetry in almost all points assessed on the hands, except for two palmar points and one dorsal point. In the feet, there was significant asymmetry in all points, indicating a greater involvement of the lower limbs.ConclusionIRT confirmed the asymmetric pattern of leprosy neuropathy, indicating a change in the function of the autonomic nervous system, and proving to be a useful method in the approach of pain.
Highlights
Leprosy is a chronic infectious disease caused by the bacillus Mycobacterium leprae [1], which, due to its high affinity for peripheral nerves, has been reported as one of the most common causes of treatable peripheral neuropathy in the world [2]
Infrared thermography (IRT) has been shown to be effective in the evaluation of peripheral autonomic function resulting from microcirculation flow changes in painful syndromes
The prevalence of neuropathic pain (NP) in leprosy has been described as 45% in China, 21% in India, 11% in Ethiopia, and 56% in Brazil; this variation in prevalence is due to the use of different study models, clinical forms of the selected patients, and screening tools [6,10,11,12]
Summary
Leprosy is a chronic infectious disease caused by the bacillus Mycobacterium leprae [1], which, due to its high affinity for peripheral nerves, has been reported as one of the most common causes of treatable peripheral neuropathy in the world [2]. Peripheral nervous system involvement occurs by two main factors, including the bacillus’s predilection for Schwann’s cell and reactions mediated by the host immune system [3]. This neural impairment often leads to changes in sensory, motor, and autonomic function [4]. Neuropathic pain (NP) has been shown to be one of the most common late complications of leprosy [8,9], which may clinically manifest continuously or intermittently and occurs in a single or in several locations [10].
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