Long-term Hyperbaric Oxygen Treatment Enhances Nerve Regeneration Pace and Rate in a Rat Sciatic Nerve Graft Model

PURPOSE: The treatment of choice for peripheral nerve injury remains microsurgical nerve repair. However, microsurgical nerve repair often achieve inconsistent limited functional regeneration depending mainly on patient’s age, comorbidities, the length of nerve defect and the duration between injury and repair. Hyperbaric oxygen (HBO) treatment was reported to enhance nerve regeneration in short-term (days) regeneration experiments. The aim of the study was to reaffirm these findings in a long-term clinically relevant HBO treatment protocol. METHOD: A nerve segment of 10 mm of the sciatic nerve was transected, inverted and coaptated as a nerve graft in 42 male Wister rats. Following surgery rats were either treated with a two months HBO treatment protocol or left untreated. Post-operative follow-up consisted of electrophysiological study (on post operative day 20, 30, 60 and 90) and immunohistochemistry and morphometric assessments (POD14, 35 and 90). RESULTS: EMG results show a faster regeneration pace in the animals exposed to HBO treatment with all the treatment group showing a recordable M wave on pod20 as in pod 30, compared to only a third from the control group on pod20 and two thirds on pod30. Immunohistochemistry analyses performed on POD35 demonstrated showed significantly improved nerve regeneration, demonstrated by enhanced axonal and myelin regrowth, nerve regeneration in POD35 in the HBO treated group compared to the control group. By pod90 the motor nerve fibers percentage in the treatment group reached normal values while the control group did not. CONCLUSION: A Long term clinically relevant HBO treatment protocol significantly enhanced peripheral nerve regeneration rate and quality.