Modeling Electric Fields in Transcutaneous Spinal Direct Current Stimulation: A Clinical Perspective.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Computational Modeling

Background:

• Clinical studies indicate transcutaneous spinal direct current stimulation (tsDCS) modulates spinal cord (SC) pathways.
• Understanding tsDCS-induced electric fields and their interaction with SC anatomy is crucial but incomplete.
• Realistic computational models based on MRI are essential for predicting these interactions.

Purpose of the Study:

• To review electric field distribution in the SC during tsDCS using MRI-based models.
• To compare computational predictions with clinical findings.
• To define the role of computational knowledge in optimizing tsDCS protocols.

Main Methods:

• Review of MRI-based computational models predicting electric field distribution in the human SC during tsDCS.
• Comparison of predicted electric field intensities with clinical outcomes from human studies.
• Analysis of factors influencing electric field distribution, including anatomy and electrode placement.

Main Results:

• tsDCS-induced electric fields are predicted to be safe, inducing transient and neuroplastic changes.
• Common tsDCS protocols generate similar electric field intensities in ventral and dorsal SC horns, correlating with observed motor and sensory effects.
• Electric fields are highly dependent on individual anatomy and electrode placement, with potential "hotspots" varying with position.

Conclusions:

• Computational models predict tsDCS is safe and can induce beneficial neural changes, suggesting potential for new clinical applications like spinal cord injury.
• Optimizing tsDCS requires individualized, patient-tailored MRI-based computational models to account for anatomical variations.
• Detailed modeling of electric field distribution can guide the tailoring of tsDCS parameters (electrode configuration, intensity, duration) for improved clinical outcomes.