Transcranial Direct Current Stimulation (tDCS) of the Primary Motor Cortex and Robot-assisted Arm Training in Chronic Incomplete Cervical Spinal Cord Injury: A Proof of Concept Sham-randomized Clinical Study

Background: After cervical spinal cord injury, current options for treatment of upper extremity motor functions have been limited to traditional approaches. However, there is a substantial need to explore more rigorous alternative treatments to facilitate motor recovery.

Objective: To demonstrate whether anodal-primary motor cortex (M1) excitability enhancement (with cathodal-supra orbital area) (atDCS) combined with robot-assisted arm training (R-AAT) will provide greater improvement in contralateral arm and hand motor functions compared to sham stimulation (stDCS) and R-AAT in patients with chronic, incomplete cervical spinal cord injury (iCSCI).

Methods: In this parallel-group, double-blinded, randomized and sham-controlled trial, nine participants with chronic iCSCI (AIS C and D level) were randomized to receive 10 sessions of atDCS or stDSC combined with R-AAT. Feasibility and tolerability was assessed with attrition rate and occurrence of adverse events, Changes in arm and hand function were assessed with Jebson Taylor Hand Function Test (JTHFT). Amount of Use Scale of Motor Activity Log (AOU-MAL), American Spinal Injury Association Upper Extremity Motor Score and Modified Ashworth Scale (MAS) at baseline, after treatment, and at two-month follow-up.

Results: None of the participants missed a treatment session or dropped-out due to adverse events related to the treatment protocol. Participants tended to perform better in JTHFT and AOU-MAL after treatment. Active group at post-treatment and two-month follow-up demonstrated better arm and hand performance compared to sham group.

Conclusion: These preliminary findings support that modulating excitatory input of the corticospinal tracts on spinal circuits may be a promising strategy in improving arm and hand functions in persons with incomplete tetraplegia. Further study is needed to explore the underlying mechanisms of recovery.