Conditioning electrical stimulation is superior to postoperative electrical stimulation, resulting in enhanced nerve regeneration and functional recovery

Postoperative electrical stimulation (PES) improves nerve regeneration by decreasing staggered regeneration at the coaptation site. By contrast, conditioning (preoperative) electrical stimulation (CES) accelerates axon extension. Given that both techniques can be delivered at the bedside, a direct comparison of outcomes is of significant clinical importance. In this study, we compared regeneration and reinnervation outcomes of CES, PES, a combination of CES and PES, and a no stimulation control. Sprague Dawley rats were randomly divided into i) CES, ii) PES, iii) CES + PES, and iv) no stimulation. CES was delivered one week prior to nerve cut/ coaptation, and PES was delivered immediately following nerve repair. Length of nerve regeneration was assessed at 7 days post-coaptation (n = 6/cohort), and behavioral testing was performed between 6 and 8 weeks post-coaptation (n = 8/cohort). Animals treated with CES had significantly longer axon extension and improved sensorimotor recovery compared to all other cohorts. CES treated axons extended 8.5 +/- 0.6 mm, significantly longer than PES (5.5 +/- 0.5 mm), CES + PES (3.6 +/- 0.7 mm), or no stimulation (2.7 +/- 0.5 mm) (p < .001). Sensory recovery (von Frey filament testing, intraepidermal nerve fiber reinnervation) (p < .001) and motor reinnervation (horizontal ladder, gait analysis, nerve conduction studies, neuromuscular junction analysis) (p < .05 - p < .001) were significantly improved in CES animals. CES significantly improves regeneration and reinnervation beyond the current clinical paradigm of PES. The combination of CES and PES does not have a synergistic effect. CES alone therefore may be a more promising treatment to improve outcomes in patients undergoing nerve repair surgeries.