The effect of intraneural damage by different mechanical injury

Cho, Kyeong Sook; Kim, Han Joong

Abstract

The ultimate goal in nerve repair is to restore sensory and motor function of the injured part. The success or failure of this goal depends upon several variables, with the mechanism of injury being one of the more crucial determining factors. At the time of nerve repair, the damaged neural tissue is resected back to what appears to be an uninjured level. However, it is often difficult to determine this level. This study was designed to compare the degree of intraneural scarring over 3-week period in experimental different injuries. In this study, nerve cut, crush, saw, and avulsion injuries were produced in male Sprague-Dawley rats. The extent of nerve damage was assessed based on histology and intraoperative observations on days 1, 8, and 21 after the post-injury. The result of this study demonstrated that the degree of injury can vary from cutting, sawing, crushing to avulsion as well as vary on period; the first 3 weeks after injury. Therefore, a dynamic pathophysiology is induced by a nerve injury. The most severe injury was caused by nerve avulsion, sawing, crushing and cutting mechanisms of injury in order. The intraoperative observation on the first day does not good predictor of the degree of injury. Especially in case of saw injury, the scope of injury was enlarged in course of time, therefore secondary repair on the nerve would be appropriate, when the progress of fibrosis was completed. The extent of injury in the avulsion group will compromise the final result if a primary neurorrhaphy is peformed. Secondary nerve grafting may be the only way to improve sensory function in these injuries. In contrast, the zone of injury in a cut nerve has a tendency to improve over the first 2 to 3 weeks. This would suggest that when an injured nerve is trimmed back to what appears to be a noninjured zone, or normal nerve, no significant additional injury is being induced.