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

ABSTRACT

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.

KEYWORDS:

• Minimally conscious state
• tDCS
• brain injury
• disorders of consciousness
• brain stimulation
• Clinical trial: NCT02019615

Acknowledgments

The authors thank Pr. Gustave Moonen, Pr. Pierre Maquet, the Neurology Department staff of the University Hospital of Liège, the ISOSL Rehabilitation Center, Centre d’Accueil de Bouge, the Foyer Saint-Anne, the University of Liège, the Duesberg Foundation, the Belgian American Educational Foundation, the Wallonie-Bruxelles International, the James McDonnell Foundation, Mind Science Foundation, IAP research network P7/06 of the Belgian Government (Belgian Science Policy), the European Commission, Human Brain Project (EU-H2020-fetflagship-hbp-sga1-ga720270), and Luminus project (EU-H2020-fetopen-ga686764). AT and OG are post-doctoral fellows, and SL is research director at FRS-FNRS.

Authorship

AT and SL designed the protocol. AT and MAB obtained the data. AT, SW and SL interpreted data and wrote the manuscript. SW and AFD analysed the data. CC and OG contributed to the writing of the manuscript. All authors were involved in editing the paper and approved the final text.

Declaration of interest

The authors report no conflicts of interest. Funding was provided by: European Commission, James S McDonnell Foundation, Belgian National Fund for Scientific Research (FNRS), Concerted Research Action, the Belgian American Educational Foundation (BAEF), the Fédération Wallonie Bruxelles International (WBI), the Massachusetts General Hospital Department of Neurology and Division of Neurocritical Care and Emergency Neurology, and the University of Wisconsin-Madison. The source of the funding of the study had no role in study design, data collection, data analysis, data interpretation or writing of the report. SL is Research Director at FNRS, OG is post-doctoral fellows at FNRS.