Avaliação ultrassonográfica de nervos periféricos de pacientes com hanseníase e contatos domiciliares

Abstract

Introduction: Leprosy neuropathy is the most common infectious peripheral neuropathy worldwide. Despite significant advances in leprosy control, it remains a public health problem and its early diagnosis represents one of the main objectives of health programs, especially in leprosy household contacts (HHCs), which represent a high-risk group for the development of leprosy. Recently, ultrasonography (US) has emerged as a new tool for the evaluation of peripheral neuropathy. Objectives: This thesis was subdivided into two studies, whose objectives were to identify neural impairment through US assessment in asymptomatic leprosy HHCs (study 1) and in patients with a confirmed diagnosis of leprosy (study 2). Materials and methods: In the first study, 49 seropositive HHCs and 30 seronegative HHCs, followed at a national leprosy reference center, and a control group composed of 53 healthy volunteers (HVs) were recruited. In the second study, 53 leprosy patients (LPs) diagnosed with leprosy were included. All participants underwent the multisegmental peripheral nerve US technique, which consisted of evaluating the measurements of the cross-sectional areas (CSAs) of the ulnar, median and tibial nerves at two points (in the tunnel and proximal to the tunnel) and the common fibular (CF) nerve at the level of the fibular head. Peripheral nerve CSAs measurements of seropositive and seronegative HHCs (study 1) and LPs (study 2) were compared with those of HVs. US data from HHCs and LPs were also compared with the results of serological (anti-PGL-I ELISA) and molecular tests. Results: In study 1, US evaluation detected neural thickening in 26.5% (13/49) of the seropositive HHCs and only in 3.3% (1/30) among the seronegative ones (p = 0.0038). The mean values of CSAs of the common fibular and tibial nerves were significantly higher in seropositive HHCs. This group also had significantly greater asymmetry in the CF and tibial nerves (proximal to the tunnel). Seropositive HHCs presented a 10.5-fold higher chance of neural impairment (OR = 10.48; p = 0.0311). On the other hand, the presence of at least one scar from BCG vaccine conferred 5.2-fold greater protection against neural involvement (OR = 0.19; p = 0.0184). In study 2, US evaluation detected neural thickening in 71.1% (38/53) of LPs, and the ulnar and tibial were the most frequently affected nerves. Among LPs with mononeuropathy, most had serological and molecular parameters of high bacillary load. All nerves showed significantly higher measurements in LPs compared with HVs, and also greater asymmetry between left and right sides, with significantly higher values for ulnar and tibial nerves. Furthermore, it is important to highlight the significant differences found in CSAs measurements between the tunnel and pre-tunnel points for the ulnar and tibial nerves, with maximum values proximal to the tunnel. All clinical forms of leprosy showed neural enlargement through the US. Conclusions: In study 1, our results demonstrated a higher prevalence of neural thickening in leprosy-seropositive HHCs. The combination of seropositivity and absence of BCG scar can identify individuals with greater chances of developing leprosy neuropathy, reinforcing the importance of including serological and imaging methods in the epidemiological surveillance of leprosy HHCs. In study 2, our results demonstrated that asymmetry and irregular neural thickening, most evident above the osteofibrous tunnel, are hallmarks of the leprosy neuropathy. Finally, our results reinforce that leprosy is a primarily neural condition. Therefore, we propose the use of multisegmental US technique of the peripheral nerves of the upper and lower limbs in the investigation of HHCs and LPs, in order to improve the diagnosis of leprosy neuropathy and prevent stigmatizing deformities and disabilities.