Previous studies showed that transcranial direct current stimulation (tDCS) transiently improves performance of motor function in stroke patients, as well as decrease muscle hypertonia. 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 manage other symptoms occurring in this population of patients, such as muscle hypertonia. In this study, investigators will assess the effects of bilateral fronto-central tDCS on spasticity as measured with the Modified Ashworth Scale (MAS) and on the Coma Recovery Scale-Revised (CRS-R) scores in patients with DOC in a double-blind sham-controlled experimental design.
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