Fronto-parietal tDCS in Severely Brain Injured Patients With Disorders of Consciousness

Effect of Fronto-parietal Transcranial Direct Stimulation on the Level of Consciousness in Patients With Disorders of Consciousness

Previous studies showed that anodal transcranial direct current stimulation (tDCS) transiently improves performance of memory and attention. In severely brain injured patients with disorders of consciousness (DOC), a single stimulation over the left dorsolateral prefrontal cortex has shown to improve patients' sign of consciousness. Nevertheless, other brain areas could be stimulated in order to increase the number of responders. In this study, investigators will assess the effects of bilateral fronto-parietal tDCS on Coma Recovery Scale-Revised (CRS-R) scores in patients with DOC in a double-blind sham-controlled experimental design.

Following severe brain damage and coma, some patients may remain in a vegetative state (VS) or minimally conscious state (MCS). At present, there are no evidence-based guidelines regarding the treatment of patients with disorders of consciousness (DOC). A previous study showed that a single stimulation (using transcranial direct current stimulation - tDCS) of the left prefrontal cortex induces an behavioral improvement in some patients in DOC. Nevertheless, only 43% of patients in MCS responded to the stimulation. Therefore, it is needed to find new protocols to increase the number of responders and improve the effect of tDCS in patients with DOC. In this study, investigators aim to assess the effect of single session anodal (i.e., excitatory) transcranial direct current stimulation (tDCS) over right and left fronto-temporal cortices (using 4 anodes and 4 cathodes), on the level of consciousness of patients with DOC, in a double blind randomized sham controlled study. The anodes will be placed over F3, F3, CP5 and CP6. tDCS is a form of safe non-invasive cortical stimulation, modulating cortical excitability under the electrodes, via weak polarizing currents. It has been reported that anodal tDCS transiently improves working memory and attention by stimulating the left DLPF in healthy subjects and patients with stroke, Parkinson's or Alzheimer's disease. By increasing the surface of the stimulated area, it is expected to increase the number of responders as patients' brain lesion are very heterogeneous and widespread.

vegetative state, minimally conscious state, disorder of consciousness, transcranial current direct stimulation, non invasive brain stimulation, neuromodulation

Patients will receive anodal tDCS (bilateral fronto-parietal stimulation) during 20 minutes preceded and followed by a clinical assessment (Coma Recovery Scale-Revised) and neurophysiological assessment (8 channels EEG).

Patients will receive sham tDCS (15 second of stimulation) during 20 minutes preceded and followed by a clinical assessment (Coma Recovery Scale-Revised) and neurophysiological assessment (8 channels EEG).

Patients will receive anodal tDCS during 20 minutes preceded and followed by a behavioral assessment (Coma Recovery Scale Revised) and an EEG. The anodes will be placed over F3, F4, CP5, and CP6 in order to stimulation the fronto-parietal cortex bilaterally.

CRS-R will be performed before and after tDCS (anodal and sham). Comparison of the treatment effect (CRS-R total score after tDCS minus before) between real and sham tDCS

8 channels EEG will be record before and after tDCS to record potential cortical changes induce by the stimulation.

Inclusion Criteria: post comatose patients patients in minimally conscious state patients with stable condition patients free of sedative drugs and Na+ or Ca++ blockers (e.g., carbamazepine) or NMDA receptor antagonist (e.g., dextromethorphan) Exclusion Criteria: premorbid neurology antecedent patients in coma patients < 28 days after the acute brain injury patients with a metallic cerebral implant cranioplasty shunt

Thibaut A, Bruno MA, Ledoux D, Demertzi A, Laureys S. tDCS in patients with disorders of consciousness: sham-controlled randomized double-blind study. Neurology. 2014 Apr 1;82(13):1112-8. doi: 10.1212/WNL.0000000000000260. Epub 2014 Feb 26.