tDCS in patients with disorders of consciousness: sham-controlled randomised double blind study

Objectives: We here assessed the effects of left dorsolateral prefrontal cortex transcranial direct current stimulation (DLPF-tDCS) on Coma Recovery ScaleRevised scores in severely brain-damaged patients with disorders of consciousness. Methods: In a double-blind sham-controlled crossover design, anodal and sham tDCS were delivered in randomized order over the left DLPF cortex for 20 minutes in patients in a vegetative state/unresponsive wakefulness syndrome (VS/UWS) or in a minimally conscious state (MCS) assessed at least one week after acute traumatic or non-traumatic insult. Clinical assessments were performed using the Coma Recovery Scale-Revised directly before and after anodal and sham tDCS stimulation. Follow-up outcome data were acquired 12 months after inclusion using the Glasgow Outcome Scale-Extended. Results: Patients in MCS (n=30, interval 43±63m, 19 traumatic, 11 non-traumatic), showed a significant treatment effect (p=0.003) as measured by CRS-R total scores. In patients with VS/UWS (n=25, interval 24±48m, 6 traumatic, 19 non-traumatic), no treatment effect was observed (p=0.952). Thirteen (43%) patients in MCS and two (8%) patients in VS/UWS further showed post-anodal tDCS related signs of consciousness, which were neither observed during the pre-tDCS evaluation nor during the preor post-sham evaluation (i.e., tDCS responders). Outcome did not differ between tDCS responders and non-responders. Conclusion: tDCS over left DLPF cortex may transient improve signs of consciousness in MCS following severe brain damage as measured by changes in Coma Recovery Scale-Revised total scores.