C.04: Motor cortex electrical stimulation to promote spinal cord injury repair in an animal model

Abstract

Background: Electrical stimulation (ES) to promote corticospinal tract (CST) repair has been recently examined, though remains under investigated. We examine the role of motor cortex ES on axonal re-growth and functional recovery in a spinal cord injury (SCI) rat model. Methods: A partial transection was performed at C4 in 48 rats. Animal groups included: ES333 rats (n=14; 333Hz, biphasic pulse, 0.2ms every 500ms), ES20 (n=14; 20Hz, biphasic pulse, 0.2ms every 1ms), SCI only (n=10), and sham (n=10; electrode insertion without ES). Rats were trained in stairwell-grasping with subsequent SCI and ES. Post-injury reaching scores were recorded weekly, and histology completed quantifying axonal re-growth. Results: Post-SCI grasping (p<0.01, ANOVA) and well reached were lower than baseline values (p<0.01, ANOVA) for all groups. ES20 animals had lower grasping scores (p=0.03, ANOVA) and farthest well reached scores post-SCI than controls (p=0.03, ANOVA). ES333 rats had more axonal collaterals (axonal sprouts rostral to lesion) compared to control animals (p<0.01, M-W). No difference was found between groups with respect to axonal regeneration into the lesion (p=0.13, ANOVA). Conclusions: Cortical ES of the injured CST results in greater axonal outgrowth, and influences functional outcomes depending on ES parameters. ES is a potentially promising SCI therapy, but further investigation is required.