Desenvolvimento de membrana contendo alizarina como teste rápido no auxílio ao diagnóstico de neuropatia diabética

Abstract

The small fiber neuropathy (SFN) integrates a heterogeneous group of diseases that affect Aδ finely myelinated fibers and C unmyelinated fibers. Its evaluation requires the use of auxiliary tests in addition to the conventional neurophysiologic techniques in which those with higher specificity, and sensibility, are mostly uncomfortable and invasive. Therefore, the objective of this work was to develop and evaluate the effect of sodium alginate polymeric membranes containing Alizarin Red (AR) and Sodium Carbonate (SC) on assisting the diagnosis of SFN in patients with diabetes. The first stage was a laboratory study for the production and characterization of the VAS and SC membranes. The second stage was the blind, non-randomized clinical trial, with three groups: people with diabetes and without neuropathy, people with diabetes and neuropathy, and people without diabetes neither neuropathy. The participants underwent the application of the membranes, DN4 (Diagnostic de Douleur Neuropathique), electroneuromyography, evaluation of silent period, and the RR interval. The median of the values of the three groups was generated by Dunn’s Test for multiple comparisons. As a result, the analysis by Differential Scanning Calorimetry Analysis (DSC) demonstrated an interaction of AR and SC with sodium alginate, enabling the formation of polymeric membranes. The swelling test showed the capacity of the membranes to react with sweat, enabling the colorimetric reaction. The evaluation of irritability by the HET-CAM (chorioallantoic membrane) assay demonstrated that the membranes have no potential for skin irritation. The Fourier Transform Infrared Spectroscopy (FTIR) analysis showed changes in the absorption bands of the membranes after the colorimetric reaction. The clinical trial demonstrated a minor color change in the group of diabetic patients with neuropathy (27,44%), indicating sweating reduction. The colorimetric reaction showed a good correlation with other tests that evaluate NFF. A moderate positive correlation was detected between Image J and VIRR (0.475 and p <0.00014). The image J correlated moderately with the initial latency of the PSC, but this was done inversely (-0.581 and p <0.0008). Image J also revealed a moderate negative correlation with DN4, which means that the higher the DN4 score, the less sweating (-0.489 and p <0.00007). The colorimetric reaction range of 0 - 40%, quantified by Image J, suggests that the individuals may present peripheral neuropathy. From the ROC curve, it was possible to demonstrate that the test developed has high sensitivity (89%) and high specificity (95%), for the diagnosis of diabetic neuropathy. The largest of the areas below the ROC curve in the tests between the groups of Diabetics with Neuropathy and Healthy individuals were DN4 (0.964 and p <0.0001), Image J (0.939 and p <0.0001), and initial PSC (0.903 and p <0.0001). Therefore, this work was able to generate a biodegradable, low-cost, easy to apply, and efficacious product to assist in the rapid diagnosis of peripheral neuropathies without presenting discomfort to patients, differentiating it from the other existing tests. Besides, its use will bring a direct benefit to the population, as it diagnoses early complications of one of the main chronic diseases in the country, positively impacting public health.