Authors: Aurore Thibaut , Marie-Aurélie Bruno, Didier Ledoux, Athena Demertzi and Steven Laureys —
Objectives: Previous studies showed that anodal transcranial direct current stimulation (tDCS) applied to the left dorsolateral prefrontal (DLPF) affected hemisphere after stroke transiently improves performance of memory (1) and attention (2). In this study, we tested the effect of tDCS on the level of consciousness in severely brain injured patients in vegetative state/unresponsive wakefulness syndrome (VS/UWS) and minimally conscious state (MCS) with a double-blind cross-over sham-controlled experimental design.
Method: We delivered anodal tDCS and sham tDCS over the left DLPF cortex during twenty minutes in 55 patients with disorders of consciousness (16 women, mean age 43±18 years, time since onset 34±58 month; 25 VS/UWS; 30 MCS). Consciousness was assessed by JFK Coma Recovery Scale Revised (3) just before and after the stimulations. Two-way repeated measures analysis of variance (ANOVA) and Skillings Mack test were performed for statistical analyses using STATA 10,0 (Stata 2007, Stata Statistical Software TX; USA).
Results: Overall, pre-versus post stimulation CRS-R scores increased more after tDCS as compared to sham stimulation (p<0.001). 17 patients showed a tDCS-induced improvement. The effect was larger in MCS as compared to VS/UWS patients (p=0.025) (figure 1). There was no effect of chronicity (p=0.064) or ethiology (p=0.86).
Conclusion and perspective: tDCS over left DLPF cortex significantly increases CRS-R score in the MCS population. Our results suggest that tDCS could be an effective tool to improve cognitive recovery in severely brain injured patients. Thanks to its easy use, it could be easily introduced into rehabilitation centers and be part of treatment for patients with disorders of consciousness.