Impotency resulting from injury to the cavernosal nerve is one of the most devastating complications of radical prostatectomy, and the fear of impotence remains one of the main causes of the unpopularity of this treatment for prostate cancer. Although the nerve sparing technique has reduced the overall impotency rate following radical prostatectomy, there exists a need for approaches that may restore erectile function through nerve regeneration. Recent clinical studies suggest that nerve grafting may promote such regeneration. Bridging of a nerve deficit with a tubular prosthesis offers an attractive alternative to nerve graft repair since it does not require harvest of a donor nerve. The objective of the current experimental study was to test the efficacy of a collagen nerve guide conduit to support and maintain axon regeneration and functional recovery of the autonomic nervous system responsible for erectile function following bilateral repair of 5-mm deficits in the rat cavernosal nerve.

The experimental model consisted of bilateral cavernosal nerve injury in young adult Sprague-Dawley rats. Three experimental groups were used: nerve crush, nerve transection and repair with a polyethylene tube and transection and repair with a collagen nerve guide. Axon regeneration and functional recovery were assessed at 28, 46 and 280 days post-injury using three complimentary methods including electrophysiological investigation of the engorgement of the corpus cavernosum, scoring based on behavioral observation and histological examination of the regenerated nerves.

After 280 days, the intra-cavernosa pressure evoked by stimulation of the cavernosal nerves repaired using the collagen nerve guide (23.6±4.9 mm Hg, n=6) returned to levels statistically equivalent to the nerve crush procedure (30.2±6.4, n=6) and were not significantly different from the normal baseline controls (40.7±5.9, n=8). The results for the polyethylene tube were significantly inferior (2.6±1.2, n=5). Scoring based on behavioral observation of sexual activity indicated that the nerve crush and collagen nerve guide repair groups were superior to the polyethylene repair group but inferior to normal. Histological examination verified that a population of myelinated and unmyelinated axons was present in all repair groups. The regenerated axon population included a great number of very small axons, which were not present in the normal controls.

The results of this study demonstrate that the collagen nerve guide supports physiological recovery of erectile function following bilateral cavernous nerve transection in the rat and suggests that a collagen nerve guide has potential for use in clinical repair of cavernosal nerve following radical prostatectomy.