Termografia para avaliação do acometimento neural das mãos de pacientes com hanseníase

Abstract

Introduction: Leprosy is caused by Mycobacterium leprae, which has a predilection for skin and peripheral nerves, where the regions are cooler. It is one of the most frequent peripheral neural diseases treatable and a large number of patients have subclinical neuropathy not evidenced by esthesiometry that evaluates tactile sensitivity with monofilaments. Objective: This study used thermography to evaluate the temperature changes in the hands of patients with different clinical forms of leprosy. For so, thermographic method that detects autonomic neural dysfunction was standardized and compared with esthesiometry. Methods: infrared images for evaluation of the hands of leprosy patients and healthy individuals aged 18 to 70 years were performed. They were divided into two groups: control (n = 20) and patients (n = 60), 10 of each clinical form. The cut off temperature was calculated for each hand in the region in different clinical forms in the dorsum and palm. A temperature threshold for the hand of patients was defined and sensitivity, specificity, accuracy, positive and negative predictive value, and positive and negative likelihood for thermography and esthesiometry were determined. Results: Via thermography, it was demonstrated that there is a temperature difference between the hands of patients and healthy controls. The average temperature in the hands of patients and controls, were 32.6 °C and 34.4 °C, respectively, with reduced difference of 1.8°C for the hands of leprosy patients. The clinical forms BL and BT were the ones with the lowest temperatures in the hands, followed by LL form. This test detected the lowest temperatures in reference area of ulnar nerve in hand in all clinical forms. Thermography showed a sensitivity of 71% for detecting temperature changes in dorsal regions and 66% in the region of the palms whereas esthesiometry showed 28.3% on the back and 56.6% in the palm for tactile sensitivity change detection. Thermography detects temperature changes in 90% of individuals with the indeterminate form, whereas esthesiometry did not detect change in any of the subjects of this clinical form. Both tests were positive predictive value, with greater sensitivity to the thermographic test, reaching 80% for the dorsum and palm of the hand in the indeterminate form which, in concept, shows no changes in sensory and/or motor neural stems. Conclusion: Early detection of temperature changes on the skin surface of the hands of patients demonstrated in the present study indicates thermography as a complementary diagnostic method of autonomic neural dysfunction in leprosy and should be available for early diagnosis in monitoring subclinical neuropathies in patients and also for surveillance of contacts, group at higher risk of becoming ill, improving prognosis and thus preventing disabilities caused by leprosy.