Modulation of Cold Pain Perception by Transcranial Direct Current Stimulation in Healthy Individuals

Objectives The aim of the current study was to evaluate the effect of transcranial direct current stimulation (tDCS) on cold pain perception in healthy individuals. Methods Anodal, cathodal (2 mA), or sham tDCSs were applied on the primary motor cortex of 22 healthy subjects in a random order. A cold pressor test was performed ten minutes after initiation of stimulation. Pain threshold and tolerance were defined as time latencies to the onset of pain perception and to the withdrawal from cold stimulus, respectively. Furthermore, pain intensity (on a scale from 0 to 10) was rated at tolerance. Results Time latencies to pain threshold and tolerance were altered by the type of stimulation (p < 0.05). Pairwise post hoc analysis revealed that anodal tDCS led to increment in pain threshold and tolerance compared with sham stimulation (13.3 ± 7.4 vs. 10.9 ± 6.0 sec for the comparison of pain threshold and 54.6 ± 26.0 vs. 45.3 ± 17.9 for the comparison of pain tolerance following anodal and sham stimulations, respectively, p < 0.05 for both comparisons). However, cathodal stimulation did not alter pain perception in comparison to anodal and sham stimulations (p > 0.05). Furthermore, pain intensity score at tolerance was not significantly affected by the type of stimulation (p > 0.05). Conclusion Anodal stimulation of the primary motor area can be utilized to alleviate cold pain perception in healthy individuals.