Multichannel tDCS to Reduce Hypertonia in Patients With Prolonged DOC

Overview

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.

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, patients with DOC suffer from other invalidating dysfunctions such as spasticity (muscle hypertonia). In sroke patients, the inhibition of the motor cortex through cathodes placed over the motor region showed to reduce spasticity. In this study, investigators aim to assess the effect of single session of transcranial direct current stimulation (tDCS) over right and left fronto-central areas (using 2 anodes and 2 cathodes), on the level of hypertonia and the level of consciousness of patients with DOC, in a double blind randomized sham controlled study. The anodes will be placed over F3 and F4, and the cathodes over C3 and C4. 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 motor functions in healthy subjects and patients with stroke or Parkinson's disease. By reducing the activity of the motor cortex (cathodes) and increasing the activity of the prefrontal cortex (anodes) we expect to observe a better motor function in patients with DOC.