3. Discussion
The purpose of this study was to quantify the effects of
hyperbaric oxygen treatment on neuropathic pain. The results
suggest that hyperbaric oxygen (HBO) treatment decreases
neuropathic pain, and this is consistent in two of the most
common nerve injury models. Overall there was not a significant
main effect of surgery type, however differences between the two
models exist with regards to treatment response over time.
Animals with the chronic constriction injury (CCI) experienced a
decrease in mechanical hypersensitivity earlier than the animals
with the L5 ligation. The effect of this treatment also appeared to
maintain itself longer for the CCI group than for the L5 group.
The exact mechanisms of hyperbaric therapy on neuropathic
pain are unknown. No studies to date have specifically investigated
the effects of HBO on neuropathic pain; rather they have only
measured other markers such as nerve regeneration and functionality.
It is possible that HBO treatment decreases pain by relieving
inflammation that is commonly found in nerve injury models.
Several studies have indicated that inflammation is a key
component to neuropathic pain. Using the CCI model, Clatworthy
et al. (1995) tested for thermal hyperalgesia in animals that
received either daily injections of dexamethasone or saline. Those
that received dexamethasone displayed significantly less thermal
hyperalgesia than saline treated animals. In the same study, they
also conducted an experiment where they applied cotton sutures
soaked in either Freund’s adjuvant or saline instead of the chromic
cat gut that is typically used in the CCI model. Animals that
received adjuvant soaked sutures displayed significantly higher