Sensory-Targeted Intraspinal Microstimulation for Spinal Cord Injury Rehabilitation.

Spinal Cord Injury (SCI) alters the excitability of neurons below the lesion, contributing to sensorimotor impairments. Less commonly acknowledged is SCI-related neuropathic pain (SCI-NP) that develops during the chronic phase of SCI, whose neural mechanisms are not yet fully understood. Previous work has demonstrated that electrical intraspinal microstimulation (ISMS) delivered amidst the spinal motor pools inside the ventral spinal gray matter causes an unexpected depression of sensory neuron responsiveness to nociceptive transmissions [1]. Given the lack of efficacious therapeutics for SCI-NP, we explored whether ISMS delivered in the sensory-dominant dorsal horn of the spinal cord could drive more robust depressive effects on pain-related transmission. Preliminary outcomes looked at population-level and single neuron-level modulatory actions of ISMS on neural transmission throughout the gray matter of a single segment of the lumbar enlargement in vivo in rats. Our preliminary results suggest dorsal ISMS may be less efficacious than motor-targeted ISMS at reducing spinal responsiveness to nociceptive sensory feedback. Future work will be required to determine the consistency of this finding and, if warranted, to optimize the stimulation parameters for multi-modal and/or pain-related applications.