A estimulação transcraniana por corrente contínua não é superior ao sham no tratamento de indivíduos com dor subacromial: ensaio clínico randomizado

Abstract

Introduction: Subacromial pain is one of the most common shoulder-related diagnoses, with persistent symptoms that reduce functionality and the quality of life of affected individuals. Transcranial direct current stimulation (tDCS) has been widely studied and presented as a promising tool in clinical practice for modulating pain perception. Objective: To analyze the effects of tDCS on pain intensity, upper limb function, quality of life, muscle strength, and shoulder range of motion in individuals with subacromial pain. Methodology: Randomized, double-blind, controlled trial. Thirty-three individuals of both sexes (mean age 42.4 ± 9.4), with a medical diagnosis of subacromial pain, were randomly allocated into two distinct groups: active tDCS (n=17) and sham tDCS (n=16). Both groups underwent 20 minutes of stimulation for 5 consecutive days. The same procedures were performed for the sham group; however, the current was interrupted after 30 seconds. The primary outcome was pain intensity, assessed by the Numerical Pain Rating Scale. Secondary outcomes were isometric muscle strength and range of motion (ROM) of shoulder flexion, extension, medial and lateral rotation, upper limb function (DASH), and quality of life (SF-36). Assessments were repeated at the end of the intervention and at a 1-week follow-up, during which participants received a guide for shoulder pain control. Results: Both groups showed similar improvements in pain intensity, DASH, and ROM compared to baseline (p<0.05). Muscle strength increased significantly over time (p<0.05), only in flexion (active tDCS) and medial rotation (sham tDCS). In the SF-36 domains, significant improvements were observed (p<0.05) in functional capacity, pain, vitality, limitations (sham tDCS), and physical aspects (active tDCS). No significant differences were observed between groups in any of the analyzed variables (p>0.05). Conclusion: The effects observed from tDCS were not superior to those of the sham group in any of the analyzed variables in individuals with subacromial pain. Thus, the observed improvements may be attributed to the placebo effect.