Improved grasp function with transcranial direct current stimulation in chronic spinal cord injury

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Biomedical Engineering

Background:

• Recovering hand function is crucial for independence in tetraplegia patients post-spinal cord injury (SCI).
• Noninvasive neuromodulation techniques like transcranial direct current stimulation (tDCS) show potential for motor function improvement in SCI.
• Chronic cervical SCI presents significant challenges to upper extremity motor control.

Purpose of the Study:

• To evaluate the effects of single-session anodal transcranial direct current stimulation (a-tDCS) at different intensities (1mA, 2mA) and sham on hand motor performance in chronic cervical SCI.
• To assess upper extremity motor performance, specifically grasp and release, using robotic kinematic analysis and the Box and Blocks test.

Main Methods:

• Eleven participants with incomplete SCI were randomized into three separate sessions.
• Each session involved 20 minutes of 1mA, 2mA, or sham a-tDCS over the motor cortex.
• Hand motor performance was quantified using robotic kinematic evaluation and the Box and Blocks (BB) test pre- and post-stimulation.

Main Results:

• A statistically significant improvement in the grasp mean to peak speed ratio (GMP) was observed in the 2mA a-tDCS group (p=0.031).
• No significant differences were found in the Box and Blocks test results across groups.
• The 2mA intervention demonstrated a positive trend for improvement in hand motor function.

Conclusions:

• A single 2mA a-tDCS session yielded measurable gains in hand motor function for chronic SCI patients, detected via robotic kinematics.
• Robotic kinematic measures proved sensitive in detecting subtle motor performance changes, outperforming traditional clinical scales in this study.
• Further research is warranted to establish tDCS as a viable long-term rehabilitation strategy for individuals with SCI.