Home-based Transcranial Direct Current Stimulation in Painful Diabetic Peripheral Neuropathy: A Double blinded, Randomized, Low-intensity Sham-Controlled Crossover Trial

Objective To evaluate the analgesic effect of four weeks home-based transcranial direct current stimulation (tDCS) compared to low-intensity sham stimulation in individuals with type 1 diabetes mellitus (T1DM) and painful diabetic peripheral neuropathy (pDPN). Materials and Methods Thirty-five participants with T1DM and pDPN were enrolled in a home-based, randomized, double-blind, sham-controlled crossover study. Each participant underwent four weeks of active (2 mA) and sham (0.3 mA) tDCS in a randomized order. Clinical and experimental endpoints were assessed before and after each treatment. The primary endpoint was pain relief, measured daily using a numerical rating scale. Secondary endpoints included various questionnaires. Quantitative sensory testing was used to assess the pain system. Results No significant differences in pain scores were observed after four weeks of active tDCS compared to sham: (mean difference in average pain 0.03 (95% CI [-0.40 to 0.46]; P=0.89, mean difference in maximal pain 0.09 (95% CI [-0.42 to 0.60]; P=0.73). However, active tDCS reduced pain compared to baseline: average pain (P=0.026) and maximum pain (P=0.012), unlike the sham tDCS. However, taking all four weeks of treatment into consideration, sham tDCS reduced pain scores (P<0.05). No differences were found between the treatments for the secondary outcomes . Responders to active tDCS showed increased temporal summation and lower pressure pain thresholds. Conclusion Active tDCS significantly reduced pain compared to the baseline but did not show an improvement over the low-intensity sham tDCS. Responders to active tDCS exhibited features of central sensitization. Stimulation intensity may influence tDCS effectiveness.