Can cavernous nerves be spared after radical prostatectomy? Evidence from animal studies

Purpose: The current study aims at evaluating penile erectile function after nerve-sparing radical prostatectomy (RP) based on evidence from a reliable animal model. The previous model in which the cavernous nerve (CN) is temporarily crushed is reviewed and compared to the present method of prostate lobes removal near the CN to determine which is more relevant to the clinical situation. Materials and Methods: Twenty-four rats were divided into three groups. One group was subjected to temporary CN crushing, one group was subject to prostate lobes removal near the CN, and the last group was preserved (sham group). All rats were re-examined at 4 weeks after the first surgical procedure. The pathological changes of the CNs were evaluated by their gross appearance and immunohistochemistry. Intracavernosal pressure (ICP) was measured as a parameter of male erectile function. Results: The results of the current study demonstrate that the removal of the prostate lobes near the CN led to the degeneration of CN, even with careful sparing techniques. Four weeks after the first surgical procedure, the rats' abdomens were reopened, and CNs were identified in only 60% of the rats with prostate lobes removal near the CN. Furthermore, the remaining CNs in this group were found to be histologically degenerated, with poorer erectile function presented by ICP. In contrast, the CNs after temporary crush were only mildly injured and demyelinated, with evidence of regeneration. The changes in the rats with prostate lobes removal near the CN are much more similar to those in rats with clinical RP with CN sparing. Conclusion: The current study concluded that, in the rat model, CNs will be injured, degenerated, and eventually disappear after prostate lobes removal near the CN; this is very similar to what is observed in clinical RP. Protection of the CNs for erectile function preservation should be investigated further using this animal model.