Transcranial Direct Current Stimulation (tDCS) and Motor Training for Traumatic Brain Injury (TBI) Survivors

The aim of this study is to compare the effect of transcranial direct current stimulation and functional upper extremity task training to functional upper extremity task training alone. The functional upper extremity task training uses the Armeo Spring robotic arm to support the limb while playing functional task games on a computer.

Specific Aims:

1. To demonstrate that tDCS combined with upper extremity functional task training in a virtual environment is more effective than functional task training in a virtual environment with sham tDCS.
2. To compare cortico-excitatory changes following training with tDCS vs. sham stimulation, using paired- and single-pulse transcranial magnetic stimulation as a tool to measure cortical excitability.

This is a randomized, double-blinded, sham-controlled study comparing sham and continuous tDCS combined with repetitive upper extremity functional task training in a virtual environment. Subjects will be randomized to 1 of 2 groups: Armeo training with continuous tDCS, or sham tDCS through a randomization stratification approach. Subjects will be grouped into strata defined by the degree of weakness, and then randomized separately within each stratum according to a block randomization of 6 to receive Armeo training-continuous tDCS, or Armeo training-sham stimulation. Each subject will receive 10 training sessions over 2 weeks. Training sessions will last for 40 minutes and will focus on repetitive tasks using the Armeo device that incorporate multidirectional reaching, grasp and release action of the hand. We will use a variety of virtual tasks (computer games) in the training. Examples of the virtual tasks include 1) picking up objects from shelves placed against different walls of a room and placing them in a bin in the center foreground of the screen, 2) picking up eggs from a basket and cracking them over a frying pan, 3) picking up objects at a virtual supermarket and placing them in the shopping cart, 4) cleaning a stove top. In between training sessions, subjects will be encouraged to use the affected arm in daily activities. This will be assessed with the Motor Activity Log.

tDCS will be delivered by positioning the anode over the primary motor cortex (M1) of the affected hemisphere, while the cathode will be placed over the unaffected M1 area. The electrode localization method will be according to the International 10-20 Electrode Placement System for placement of EEG electrodes. This method has been validated with a frameless stereotactic system. Direct current will be transferred by a saline-soaked pair of surface sponge electrode (35cm2) and delivered by a battery-driven, constant current stimulator with a maximum output of 10mA. An intensity of 1mA will be used in this study (current density of 0.04 μA/cm2). Continuous stimulation will be delivered at an intensity of 1mA while the subject undergoes the 40-minute Armeo motor training sessions. For sham stimulation, the same parameters will be employed. However, the current will be applied for 30 seconds only. Current intensity will be gradually increased and decreased to diminish its perception.

Outcome measures will be performed prior to treatment initiation, at day 5, 10, and at follow-up week 1, 2 and 4 after the end of treatment. A rater blinded to the treatment will assess the effects of the intervention using the Jebsen-Taylor Hand Function Test and Box and Block Test.

Eligibility Criteria:
Inclusion Criteria:

* Age 18-70 years
* First-time moderate to severe TBI
* Arm weakness

Exclusion Criteria:

* History of seizures
* Major depression
* Agitated Behavior Scale \>21
* Cognitive Impairment that interferes with understanding instructions
* Pregnancy
* Implants (e.g. metal plates, shunts, pacemaker)
* Participation in other upper extremity rehab or TBI study