Effects of cryotherapy on the palmar and plantar digital nerves in the horse.

This paper researched the effects of two different cryotherapy techniques on the palmar and plantar nerves in horses, primarily analyzing their duration of anesthesia and any histopathologic alterations. The study concluded that freezing the nerves directly post-surgical exposure had longer anesthetic effects and was potentially useful for temporary neurectomies in horses.

Objective and Methods

• The study aims to evaluate the longevity of anesthetic effect and any histopathologic transformations that occur due to a regulated freeze of the palmar and plantar digital nerves in horses.
• Two techniques of cryotherapy were compared: nerves frozen directly with a cryoprobe after surgical exposure versus nerves frozen percutaneously via a cryoprobe applied to the overlying skin.
• The return of skin sensation and the horse’s capacity to perceive a stimulus were markers used to measure the return of nerve function.

Results: Duration of Anesthetic Effect

• The study found that the duration of anesthetic effect was markedly longer, specifically at a statistical significance of P less than 0.005, in the nerves that were frozen directly after surgical exposure compared to those frozen percutaneously.
• In terms of time, the direct freeze technique averaged an anesthetic effect duration of 156 days against 47.5 days for the percutaneous technique.

Results: Histopathologic Changes

• At the end of the experiment, horses were euthanized and all nerves underwent histological examination.
• A neuroma–a type of nerve tumour–in continuity were observed in 10 out of 28 frozen nerves. The classification was based on the degree of involvement of the nerve’s supporting fibrous connective tissues, including the endoneurium, perineurium, and epineurium.

Conclusions

• The direct technique of freezing the nerve after surgical exposure was found to be repeatable and provided a potential option for temporary neurectomy in horses.
• Despite causing a temporary loss of pain perception, the percutaneous technique could not reliably interrupt nerve function for more than a few weeks.