Evaluation of the Separate and Combined Effects of Anodal tDCS over the M1 and F3 Regions on Pain Relief in Patients with Type-2 Diabetes Suffering from Neuropathic Pain

Neuropathic pain (NP) is a common complication of chronic diabetes that negatively affects the routine functioning and sleep of patients. The present study aimed to investigate the separate and combined effects of anodal transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) and left dorsolateral prefrontal cortex (F3) regions on pain relief in patients with type-2 diabetes suffering from NP. The statistical population of this double-blind randomized clinical trial consisted of all the members of the Bonab Diabetes Association in 2022 aged 45 to 65 years who were diagnosed with NP by a specialist. A total of 48 patients who met the inclusion criteria were selected as the sample through purposive sampling. The participants were then randomly assigned into 4 groups, each attending 12 sessions of a special intervention (three times a week). The Short Form-McGill Pain Questionnaire-2 (SF-MPQ-2) was used for data collection. Data were statistically analyzed using SPANOVA, analysis of covariance, and the Bonferroni test. The results showed that perceived pain intensity significantly changed in all groups over time (F=11.48, P<0.001). The mean perceived pain intensity in the posttest was significantly lower in the M1 stimulation group than in the F3 stimulation group. Nevertheless, there was no significant difference between the two groups in terms of perceived pain intensity in the one-month and two-month follow-up stages. Considering its therapeutic potential for pain relief, the application of tDCS (over both M1 and F3) can be expanded for diabetic patients.