Multichannel tDCS to Reduce Hypertonia in Patients With Prolonged DOC

Effects of Multichannel Transcranial Direct Current Stimulation to Reduce Hypertonia in Patients With Prolonged Disorders of Consciousness: a Pilot Study.

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.

transcranial direct current stimulation, disorder of consciousness, muscle hypertonia, spasticity, vegetative state, minimally conscious state

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

Patients will receive sham tDCS (5 seconds of stimulation) during 20 minutes preceded and followed by a clinical assessment (Modified Ashworth Scale and Coma Recovery Scale-Revised) and neurophysiological assessment (8 channels EEG).

tDCS will be applied during 20 minutes with a current of 1 mA preceded and followed by a behavioral assessments (Modified Ashworth Scale and Coma Recovery Scale Revised) and an EEG. The anodes will be placed over F3 and F4 and the cathodes over C3 and C4.

Modified Ashworth Scale (MAS) will by assessed before and after tDCS (active and sham). Comparison of treatment effect (MAS score after tDCS minus before) between active and sham tDCS. The MAS is a 5 points scale going from 0 (no spasticity) and 5 (extreme spasticity).

Coma Recovery Scale Revised (CRS-R) will be performed before and after tDCS (anodal and sham). Comparison of the treatment effect (CRS-R total score score after tDCS minus before) between real and sham tDCS. The CRS-R is 23 points scale with 6 sub-scales (lower scores refer to reflexes, while higher scores refer to more complex behaviors). The total score is the sum of the scores in the 6 sub-scales.

8 channels electroencephalography (EEG) will be record before and after tDCS to record potential cortical changes induce by the stimulation. EEG power will be compared in different bandwidths (delta, theta, alpha, beta).

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.