The cavernous nerve, which is responsible for erectile function, may be injured or resected during prostatectomy.  It can be reconstructed using nerve grafts in an attempt to restore function.  However, the clinical benefits cavernous nerve grafting are difficult to determine without specific histologic or functional evidence of potency.   A large animal model to examine the role of the cavernous nerve and the effects of nerve grafting on impotence would allow for a better understanding of the potential risks and benefits of reconstruction.

            The study was performed on mongrel dogs with two separate arms: the first arm consisted of an anatomic dissection and analysis of the cavernous nerve, and the second arm was experimental to determine the effects of cavernous nerve resection and grafting on impotence. Anatomic dissections (n=15) were performed in dogs with identification, mapping, and histomorphometric analysis of the cavernous nerve.  Histomorphometric analysis included: total number of nerves, percent nerve, density, fiber width, and fascicular number.  The experimental arm of this study (n=8) involved the determination of pre-operative potency, exploration and resection of the cavernous nerve, determination of post-operative potency, and cavernous nerve grafting over 6 months. 

            The anatomic study identified the position of the cavernous nerve and its response to both trans-rectal and direct stimulation. The histomorphometric analysis defined the histologic pattern of the nerves in the region.  The experimental arm confirmed impotence in 6 of 7 control animals following nerve ablation. The response to trans-rectal stimulation, recorded in centimeters of penile tumescence, is listed in the table below. One control animal died post-operatively and the sham animal recovered erectile function immediately following surgery.

            In conclusion, the anatomic arm of the study confirmed the position and histomorphology of the cavernous nerve in the dog model.  The cavernous nerve plexus demonstrated remarkable consistency with a fascicular pattern amenable to nerve grafting.  The experimental arm of the study showed that cavernous nerve ablation resulted in long term loss of erectile function. This study establishes a clinically relevant large animal model to further investigate the potential risks and benefits of cavernous nerve reconstruction in humans.