Multisite Transcranial Direct Current Stimulation to Promote Hand Function Recovery After Stroke

Multisite Transcranial Direct Current Stimulation Targeting Motor Network by Mapping Electric Fields With Task-based fMRI to Promote Hand Function Recovery After Stroke

A novel multisite high definition tDCS (HD-tDCS) in healthy people showed that such network-targeted stimulation could enhance motor excitability beyond traditional stimulation which targeting only one region. It showed that the excitability following multisite HD-tDCS was more than double the increase following conventional tDCS. To consider the various lesion site of different stroke survivors. The electrode placements based on personalized lesion profiles and anatomical features can be determined using finite element modeling, with lesion profiles generated from fMRI and advanced algorithms calculating the current density to maximize the modulation effect. Combining motor network interaction and the new multisite electrode montage may further provide a potential to facilitate stroke recovery.

Constant current (1mA) will be applied for 20min and the anode will be placed over the standard C3/C4 position

The stimulator will be applied for 20 minutes with only 30s ramp-up and ramp-down stimulation delivered.

The stimulation electrodes are fixed on the ipsilesional sensorimotor cortex according to the brain activation map detected by task based fMRI.

The stimulator will be applied for 20 minutes with only 30s ramp-up and ramp-down stimulation delivered.

5-8 sintered Ag/AgCl ring electrodes will be placed based on the neuroimaging and computation modelling. The electrodes will be placed inside plastic electrode holders which will be filled with gel to have good contact with the scalp.

A pair of 25 cm2 rubber electrodes enclosed in saline-soaked sponges and affixed to the head with rubber bands.

Multisite HD-tDCS will individual stimulation montages with robot hand training will be applied on chronic stroke survivors. In the multisite HD-tDCS group, 5-8 sintered Ag/AgCl ring electrodes will be placed based on the neuroimaging and computation modelling. The location of the electrodes will be identified by the individual brain activity in the primary motor cortex derived from tasked-based fMRI. The Finite Element Model (FEM) will be used to simulate the electric field distribution on individual brain. Optimization of stimulation montages will be based on the derived activation pattern of the brain. After 20-minute multisite HD-tDCS, EMG-driven robot hand training will be conducted.

Sham stimulation with robot hand training will be applied on chronic stroke survivors. A pair of 25 cm2 rubber electrodes enclosed in saline-soaked sponges and affixed to the head with rubber bands. After the sham stimulation, EMG-driven robot hand training will be conducted.

The ARAT is a 19-item measure divided into 4 sub-tests (grasp, grip, pinch, and gross arm movement) to assess upper limb functioning

It is used to evaluate and measure upper-limb recovery in post-stroke hemiplegic patients, and items are scored on a 3-point ordinal scale

It is used to investigate the changes in corticomuscular coherence for studying connectivity between the brainwave using EEG and the affected hand muscles using EMG. In addition, EMG will be used to detect muscle activation change and muscle co-contraction pattern alteration.

It is used to identify neural correlates of stimulation-induced behavioral gains for investigating tDCS-induced changes in brain activations

Inclusion Criteria: first-ever stroke, the duration after stroke exceeds 12 months; mild to moderate upper extremity motor function deficit, determined by the Fugl-meyer assessment of upper extremity (FMAUE) scores between 15 and 53; detectable voluntary muscle sEMG signal from flexor digitorum (FD) and extensor digitorum (ED); scored below 3 in the Modified Ashworh Score (MAS) of FD and ED; sufficient cognitive function to follow the assessment and training instructions, determined by Mini Mental State Examination score of more than 21. Exclusion Criteria: history of epilepsy, or any other contradictions of brain stimulation; severe joint contracture of elbow or shoulder, or pain induced by any other neurological, neuromuscular, and orthopedic diseases.