Single tDCS session of motor cortex in patients with disorders of consciousness: a pilot study

ABSTRACT

Primary Objective: Patients with disorders of consciousness (DOC) face a lack of treatments and risk of misdiagnosis, potentially due to motor impairment. Transcranial direct current stimulation (tDCS) showed promising results over the prefrontal cortex in DOC and over the primary motor cortex (M1) in stroke. Tis pilot study aimed at evaluating the behavioral effects of M1 tDCS in patients with DOC.

Research Design: In this randomized double-blind sham-controlled crossover trial, we included 10 patients (49 ± 22 years, 7 ± 13 months since injury, 4 unresponsive wakefulness syndrome, 6 minimally conscious state, 5 traumatic etiologies).

Methods and Procedures: One session of tDCS (2 mA for 20 min) and one session of sham tDCS were applied over M1 in a randomized order with a washout period of minimum 24 h and behavioral effects were assessed using the CRS-R. At the group level, no treatment effect was identified on the total score (p = .55) and on the motor subscale (p = .75). Two patients responded to tDCS by showing a new sign of consciousness (visual pursuit and object localization).

Conclusions: One session of M1 tDCS failed to improve behavioral responsiveness in patients with DOC. Other application strategies should be tested.

KEYWORDS:

• Transcranial direct current stimulation (tDCS)
• disorders of consciousness
• motor cortex
• unresponsive wakefulness syndrome
• minimally conscious state

Acknowledgments

We thank the whole staff from the Neurology department, University Hospital of Liège, as well as, patients, and their families.

Conflicts of interest

The authors declare no conflicts of interest.

Additional information

Funding

The study was supported by the University and University Hospital of Liège, the French Speaking Community Concerted Research Action [ARC 12-17/01]; the Belgian National Funds for Scientific Research [FRS-FNRS]; Human Brain Project [EU-H2020-fetflagship-hbp-sga1-ga720270]; Luminous project [EU-H2020-fetopen-ga686764]; DOCMA project [EU-H2020-MSCA–RISE–778234]; the James McDonnell Foundation, Mind Science Foundation, IAP research network P7/06 of the Belgian Government [Belgian Science Policy]; the European Commission, the Public Utility Foundation ‘Université Européenne du Travail’, “Fondazione Europea di Ricerca Biomedica”, the Bial Foundation.