Intervention Effect of Transcranial Alternating Current Stimulation (tACS) on Disorder of Consciousness (DOC)

To investigate the effect of high definition-transcranial alternating current stimulation(HD-tACS) on consciousness promotion in patients with chronic consciousness disorders and the underlying neural mechanism by EEG.

Forty patients with chronic consciousness disorder who met the inclusion criteria were recruited with the informed consent of the family. All the participants were randomized to receive "active" or "sham" treatment protocol. Stimulation was performed using a alternating stimulator linked to one anodal electrode and four cathodal electrodes. The anodal electrode was placed over the left dorsolateral prefrontal cortex (DLPFC; F3 in the 10-20 international system of EEG placement), and the four cathodal electrodes (AFz, FCz, F7, and C5 in the 10-20 international system EEG placement) were placed around the anodal electrode to form a current loop. Twenty 2 milliampere (mA) sessions (ramp-up and ramp-down periods of 30 and 30 seconds, respectively) were applied for 20 minutes per session, twice daily over 10 consecutive days, and the stimulus frequency was set as 6 Hertz (Hz). Sham tACS was delivered using the same protocol and current intensity, but the period of active stimulation was only during the ramp-up and ramp-down periods of 30 and 30 seconds. Before and after the tACS treatment, the state of consciousness was assessed according to coma recovery scale-revised(CRS-R), and19-channel EEG data were collected.