The effect of transcutaneous spinal direct current stimulation on corticospinal excitability in chronic incomplete spinal cord injury

Abstract

OBJECTIVES:This study investigated the feasibility of modulating bilateral corticospinal excitability with different polarities of transcutaneous spinal direct current stimulation (tsDCS) in chronic, incomplete spinal cord injury (SCI).METHODS:Six subjects with chronic incomplete SCI (>12 months post injury) participated in this crossover study. Intervention consisted of 3 sessions, separated by at least 1 week, in which each subject received the conditions cathodal, anodal, and sham tsDCS. Stimulation was delivered at 2.5 mA for 20 minutes with the active electrode positioned over the spinous processes of T10-T11 and the reference electrode over left deltoid. To measure the effects of tsDCS on corticospinal excitability, motor evoked potentials (MEPs) from transcranial magnetic stimulation were measured bilaterally from soleus before and after tsDCS.RESULTS:Five subjects completed all 3 sessions. One subject withdrew after 2 sessions due to complications unrelated to the study. MEPs were measurable in 5 subjects. No significant differences in change of MEP amplitudes were found between the 3 conditions. However, there were trends that indicated laterality of response, particularly with cathodal tsDCS increasing corticospinal excitability contralateral to the reference electrode and decreasing corticospinal excitability ipsilateral to the reference electrode.CONCLUSION:Corticospinal excitability may be modulated with laterality by tsDCS in individuals with chronic, incomplete SCI. Further research is needed to 1) determine whether different placement of the reference electrode can lead to uniform modulation bilaterally, and 2) reveal whether these alterations in corticospinal excitability can lead to improved movement function in individuals with chronic, incomplete SCI.

Effect of transspinal direct current stimulation on afferent pain signalling in humans

“…It has also been shown that spinally applied DC stimulation, apart from more local effects [17] may have effects without delay and at large distances such as regarding function of the cerebral cortex including aspects that might relate directly to pain perception [18][19][20]. These findings may be due to far field effects of the induced electric field and thus depend on the localisation of the return electrode [21][22][23]. By all reason, they could also be due to afferent activity induced in spinal tracts.…”

Ergogenic Effects of Bihemispheric Transcranial Direct Current Stimulation on Fitness: a Randomized Cross-over Trial

“…Moreover, several works pinpointed the lack of standardized protocols in order to control for the tDCS-triggered neuromuscular responses [12,13]. Whatever the legitimate usage, the high viability of a compact tDCS set-up, such as a headset, might facilitate and boost muscular performance and adherence to physical activity for a variety of different populations, either recovering from depression [14], spinal cord injuries [15][16][17], or healthy subjects undergoing high-intensity training [18]. Since evidence in this field has been accumulating, particularly for favorable and safe tDCS effects on exercise capacity, it might be worthy studying an acute, user-friendly, tDCS administration prior to exercise in healthy participants.…”

The Role of Supraspinal Structures for Recovery after SCI: From Motor Dysfunction to Mental Health

“…Cathodal or anodal stimulation can be applied, and corticospinal excitability evaluated in recorded muscles by TMS [135] or spinal reflexes [136]. Although nonsignificant results have been reported, modifications in MEPs suggest differences in cathodal versus anodal stimulation, meaning lateralization in responses depending on the location of the reference electrode [135]. Cathodal tsDCS stimulation did not show differences in spinal reflexes compared to sham stimulation [136].…”

“…Few studies have used the transcutaneous spinal Direct Current Stimulation (tsDCS) technique to study motor activation in complete and incomplete SCI. Cathodal or anodal stimulation can be applied, and corticospinal excitability evaluated in recorded muscles by TMS [135] or spinal reflexes [136]. Although nonsignificant results have been reported, modifications in MEPs suggest differences in cathodal versus anodal stimulation, meaning lateralization in responses depending on the location of the reference electrode [135].…”