Effects of Phase Polarity and Charge Balance Spinal Cord Stimulation on Behavior and Gene Expression in a Rat Model of Neuropathic Pain

Objective To investigate the effect of phase polarity and charge balance of spinal cord stimulation (SCS) waveforms on pain behavior and gene expression in a neuropathic pain rodent model. We hypothesized that differing waveforms will result in diverse behavioral and transcriptomics expression due to unique mechanisms of action. Materials and Methods Rats were implanted with a four‐contact cylindrical mini‐lead and randomly assigned to two control (no‐pain and pain model) and five test groups featuring monophasic, as well as charge‐unbalanced and charge‐balanced biphasic SCS waveforms. Mechanical and cold allodynia were assessed to measure efficacy. The ipsilateral dorsal quadrant of spinal cord adjacent to the lead was harvested post‐stimulation and processed to determine gene expression via real‐time reverse‐transcriptase polymerase chain reaction (RT‐PCR). Gene expression, SCS intensity (mA), and behavioral score as percent of baseline (BSPB) were statistically analyzed and used to generate correlograms using R‐Studio. Statistical analysis was performed using SPSS22.0, and p