Numerical modelling of temperature increase induced by transcutaneous Spinal Direct Current Stimulation (tsDC)

Transcutaneous spinal direct current stimulation is a well-tolerate biomedical technique used to modulate the activity of spinal nervous system. In the perspective to broad its use for better treating spinal injuries, new clinical protocols with higher current intensities are likely to be adopted. However, these can be introduced without a previous assessment of safety, which is not yet investigated for the current 3 mA stimulation. Safety of this technique is mainly associated to the temperature increase due to Joule heating not only in the spinal cord and nerves but also in the skin and in the possibly more vulnerable organs. In this study, temperature increase induced in these organs of different human body models is assessed through a computational approach which solves Laplace equation followed by Bioheat equation. Results show very low heating in all the tissues and body models considered and therefore suggest to exclude the role of Joule heating in the few side effects that current protocols have shown.