The effect of low-dose external beam radiation on extraneural scarring after peripheral nerve surgery in rats

Scar tissue is an inevitable result of peripheral nerve surgery. A variety of substances have been used to prevent epineurial scarring. In this study, the effect of low-dose radiation therapy on epineurial scarring was investigated.

Seventy-eight male Sprague-Dawley rats were studied. A total of 60 rats were subjected to one of three types of surgical procedure on the sciatic nerve, as follows: Procedure 1, external neurolysis (n = 20); Procedure 2, abrasive injury (n = 20); and Procedure 3, anastomosis (n = 20). On the left sciatic nerves, 700 cGy external beam radiation was administered 24 hours after surgery, and the right sciatic nerves served as a control group (surgery only). Eighteen animals without surgical intervention were used to establish the fibrotic effect of radiotherapy on normal nerves. A neurological examination was performed weekly. Six weeks after surgery, the extent of extraneural scarring was examined by gross microdissection by means of a numerical grading scheme and histological analysis. Cellular density and surface measurements of scar tissue were also evaluated.

The dissection around the nerve was easier in rats treated with low-dose radiation compared with the control group. Furthermore, grading scores in both nerve adherence and nerve separability were significantly lower in treated nerves than in the control group (P < or = 0.05). Low-dose radiotherapy decreased the scores of cellular density and surface measurement of scar tissue (P < or = 0.05). In normal nerves, radiotherapy did not produce any fibrotic effects and the density of fibroblasts/fibrocytes was also very low.

In the case of surgery or local trauma to peripheral nerve, the use of low-dose radiation therapy may be a safe method of limiting postoperative epineurial scar formation.