Investigating the efficacy of transcranial direct current stimulation on chronic pain management in endometriosis patients: A randomized controlled trial protocol.

Introduction: Similar to chronic pain conditions, individuals with endometriosis can be affected by central sensitization syndrome (CSS), which is characterized by a loss of analgesia and central amplification of pain. Transcranial direct current stimulation (tDCS) has shown potential as an effective intervention to improve pain generated by other chronic pain conditions impacted by CSS, such as fibromyalgia and chronic pelvic issues. This study aims to evaluate the effectiveness of tDCS on pain, fatigue, and quality of life among patients affected by endometriosis.

Methods: This is a single-center, parallel, double-blinded, randomized, controlled clinical trial protocol study. We aim to recruit 40 participants affected by endometriosis (active group, n = 20; sham group, n = 20). Anodal tDCS will be delivered at an intensity of 2mA, applied over the primary motor cortex for 20 minutes per day for 10 consecutive days. There will be four assessment times: 1 week before beginning the intervention; on the 10th day following the last tDCS session; and 1 and 2 months after the last tDCS session. Pain evaluated by the algometry will be the primary outcome. Pain intensity, quality of life, fatigue, and global perception of change will be the secondary outcomes. We will calculate the effects of the active versus sham stimulation on primary and secondary outcomes by using generalized estimated equations or mixed model analysis. The effect size calculation will represent the effect measure. We expect that only the active group show reductions in pain, fatigue, and quality of life. The results of this trial will produce an important first step in providing evidence on the effectiveness of neuromodulation for the management of pain and will provide data to support new studies on tDCS.

Registration: Brazilian Clinical Trials Registry (RBR-4q69573).