Controlled clinical trial of repeated prefrontal tDCS in patients with chronic minimally conscious state.

OBJECTIVES

To assess the effects of repeated transcranial direct current stimulation (tDCS) sessions on the level of consciousness in chronic patients in minimally conscious state (MCS).

METHODS

In this randomized double-blind sham-controlled crossover study, we enrolled 16 patients in chronic MCS. For 5 consecutive days, each patient received active or sham tDCS over the left prefrontal cortex (2 mA during 20 min). Consciousness was assessed with the Coma Recovery Scale-Revised (CRS-R) before the first stimulation (baseline), after each stimulation (day 1-day 5) and 1 week after the end of each session (day 12).

RESULTS

A treatment effect (p = 0.013; effect size = 0.43) was observed at the end of the active tDCS session (day 5) as well as 1 week after the end of the active tDCS session (day 12; p = 0.002; effect size = 0.57). A longitudinal increase of the CRS-R total scores was identified for the active tDCS session (p < 0.001), while no change was found for the sham session (p = 0.64). Nine patients were identified as responders (56%).

CONCLUSION

Our results suggest that repeated (5 days) left prefrontal tDCS improves the recovery of consciousness in some chronic patients in MCS, up to 1 week after the end of the stimulations.