Advertisement

Transcranial direct current stimulation unveils covert consciousness

Published:February 07, 2018DOI:https://doi.org/10.1016/j.brs.2018.02.002
      Thanks to modern neuroimaging techniques it appears that 30% of clinically unresponsive patients (i.e., unresponsive wakefulness syndrome – UWS [
      • Bruno M.-A.
      • Vanhaudenhuyse A.
      • Thibaut A.
      • Moonen G.
      • Laureys S.
      From unresponsive wakefulness to minimally conscious PLUS and functional locked-in syndromes: recent advances in our understanding of disorders of consciousness.
      ]) retain cerebral functions that are similar to patients in a minimally conscious state – MCS [
      • Bruno M.-A.
      • Vanhaudenhuyse A.
      • Thibaut A.
      • Moonen G.
      • Laureys S.
      From unresponsive wakefulness to minimally conscious PLUS and functional locked-in syndromes: recent advances in our understanding of disorders of consciousness.
      ], as assessed by fluorodeoxyglucose positron emission tomography (FDG-PET), functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). These patients are newly labeled as MCS* or with cognitive-motor dissociation [
      • Schiff N.D.
      Cognitive motor dissociation following severe brain injuries.
      ,
      • Gosseries O.
      • Zasler N.D.
      • Laureys S.
      Recent advances in disorders of consciousness: focus on the diagnosis.
      ]. Even if the majority of them will regain some signs of consciousness, techniques to promote their recovery are still lacking. In this context, transcranial direct current stimulation (tDCS) has been shown to improve the recovery of signs of consciousness in a subset of patients in MCS [
      • Thibaut A.
      • Bruno M.A.
      • Ledoux D.
      • Demertzi A.
      • Laureys S.
      tDCS in patients with disorders of consciousness: sham-controlled randomised double blind study.
      ]. This technique offers a safe, inexpensive and easy-to-use tool to stimulate patients' brains in a non-invasive manner. Based on previous studies, the dorsolateral prefrontal cortex (DFPLC) seems to be the most relevant area to target [
      • Thibaut A.
      • Schiff N.D.
      New therapeutic options for the treatment of patients with disorders of consciousness: the field of neuromodulation.
      ].
      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'

      References

        • Bruno M.-A.
        • Vanhaudenhuyse A.
        • Thibaut A.
        • Moonen G.
        • Laureys S.
        From unresponsive wakefulness to minimally conscious PLUS and functional locked-in syndromes: recent advances in our understanding of disorders of consciousness.
        J Neurol. 2011; 258: 1373-1384https://doi.org/10.1007/s00415-011-6114-x
        • Schiff N.D.
        Cognitive motor dissociation following severe brain injuries.
        JAMA Neurol. 2015; 72: 1413-1415https://doi.org/10.1001/jamaneurol.2015.2899
        • Gosseries O.
        • Zasler N.D.
        • Laureys S.
        Recent advances in disorders of consciousness: focus on the diagnosis.
        Brain Inj. 2014; 28: 1141-1150https://doi.org/10.3109/02699052.2014.920522
        • Thibaut A.
        • Bruno M.A.
        • Ledoux D.
        • Demertzi A.
        • Laureys S.
        tDCS in patients with disorders of consciousness: sham-controlled randomised double blind study.
        Neurology. 2014; 82: 1112-1118
        • Thibaut A.
        • Schiff N.D.
        New therapeutic options for the treatment of patients with disorders of consciousness: the field of neuromodulation.
        in: Schnakers C. Laureys S. Coma Disord. Conscious. Springer, London2017: 207-223
        • Giacino J.T.
        • Kalmar K.
        • Whyte J.
        The JFK Coma Recovery Scale-Revised: measurement characteristics and diagnostic utility.
        Arch Phys Med Rehabil. 2004; 85: 2020-2029
        • Monti M.M.
        • Vanhaudenhuyse A.
        • Coleman M.R.
        • Boly M.
        • Pickard J.D.
        • Tshibanda L.
        • et al.
        Willful modulation of brain activity in disorders of consciousness.
        N Engl J Med. 2010; 362: 579-589https://doi.org/10.1056/NEJMoa0905370
        • Cruse D.
        • Chennu S.
        • Chatelle C.
        • Bekinschtein T.A.
        • Fernández-Espejo D.
        • Pickard J.D.
        • et al.
        Bedside detection of awareness in the vegetative state: a cohort study.
        Lancet. 2011; 378: 2088-2094https://doi.org/10.1016/S0140-6736(11)61224-5
        • Schiff N.D.
        Recovery of consciousness after brain injury: a mesocircuit hypothesis.
        Trends Neurosci. 2010; 33: 1-9https://doi.org/10.1016/j.tins.2009.11.002
        • Thibaut A.
        • Di Perri C.
        • Chatelle C.
        • Bruno M.A.
        • Bahri M.A.
        • Wannez S.
        • et al.
        Clinical response to tDCS depends on residual brain metabolism and grey matter integrity in patients with minimally conscious state.
        Brain Stimul. 2015; 8: 1116-1123https://doi.org/10.1016/j.brs.2015.07.024