Spinal cord stimulation in experimental chronic painful diabetic polyneuropathy: Delayed effect of High-frequency stimulation

BackgroundSpinal cord stimulation (SCS) has been shown to provide pain relief in painful diabetic polyneuropathy (PDPN). As the vasculature system plays a great role in the pathophysiology of PDPN, a potential beneficial side-effect of SCS is peripheral vasodilation, with high frequency (HF) SCS in particular. We hypothesize that HF-SCS (500Hz), compared with conventional (CON) or low frequency (LF)-SCS will result in increased alleviation of mechanical hypersensitivity in chronic experimental PDPN. MethodsDiabetes was induced in 8-week-old female Sprague-Dawley rats with an intraperitoneal injection of 65mg/kg of streptozotocin (n=44). Rats with a significant decrease in mechanical withdrawal response to von Frey filaments over a period of 20weeks were implanted with SCS electrodes (n=18). Rats were assigned to a cross-over design with a random order of LF-, CON-, HF- and sham SCS and mechanical withdrawal thresholds were assessed with von Frey testing. ResultsCompared with sham treatment, the average 50% WT score for 5Hz was 4.88g higher during stimulation (p=0.156), and 1.77g higher post-stimulation (p=0.008). CON-SCS resulted in 50% WT scores 5.7g, and 2.51g higher during (p=0.064) and after stimulation (p<0.004), respectively. HF-SCS started out with an average difference in 50% WT score compared with sham of 1.87g during stimulation (p=0.279), and subsequently the steepest rise to a difference of 5.47g post-stimulation (p<0.001). ConclusionsWe demonstrated a delayed effect of HF-SCS on mechanical hypersensitivity in chronic PDPN animals compared with LF-, or CON-SCS. SignificanceThis study evaluates the effect of SCS frequency (5-500Hz) on mechanical hypersensitivity in the chronic phase of experimental PDPN. High frequency (500Hz) - SCS resulted in a delayed effect- on pain-related behavioural outcome in chronic PDPN.