Overcoming obstacles: nerve-sparing issues in radical prostatectomy.

PURPOSE To review, compare, and contrast recovery of potency after robot-assisted radical prostatectomy with specific regard to thermal and excisional nerve injury. Our goal was to compare intensity of injury and ability to recover potency in order to stratify risk by injury type. METHODS We compare potency outcomes in our first 500 consecutive cases of robot-assisted radical prostatectomy. This is a retrospective review of data collected prospectively into an electronic database. Preoperative inclusion criteria were age less than 66 years, International Index of Erectile Function Score of 22-25, and unilateral or bilateral nerve preservation. Potency data were collected via patient-reported validated questionnaires. Potency was defined with two affirmative responses to: "erections hard enough for sexual intercourse" and were they "satisfactory." Results were collated and graphically analyzed so that time-line comparisons of recovery could be evaluated. RESULTS Time-line curves were generated comparing recovery of sexual function over 2 years after nervesparing techniques using cautery versus cautery-free and unilateral versus bilateral nerve preservation. Use of no cautery improved early return of sexual function 4.7-fold over cautery. Whether using cautery or cautery-free techniques, a doubling of nerve tissue from one nerve to two nerves spared only resulted in a 1.2-fold improvement of potency recovery both early and long-term. CONCLUSIONS In our experience, avoidance of thermal injury produces nearly a 5-fold improvement in early return of sexual function. Furthermore, thermal injury appears to induce a dense but largely recoverable injury after 2 years. In contrast to common belief, our results demonstrated that preservation of just one nerve will, in the majority of patients, result in similar potency recovery to that with two nerves preserved. Crossover innervation of the one nerve is favored over compensation and hints that techniques that increase nerve volume at the expense of positive surgical margins may need careful introspection.