Objective Assessment of Residual Nerve Tissues in Radical Prostatectomy Specimens by Immunohistochemical Staining of Neuronal Nitric Oxide Synthase–positive Nerves and Its Impact on Postoperative Erectile Function

ObjectiveTo compare the quality of surgical management of the neurovascular bundle (NVB) by assessment of neuronal nitric oxide synthase (nNOS)–positive nerves in surgical specimens between open retropubic radical prostatectomy (RP; ORRP) and robot-assisted RP (RARP).MethodsThis study included 65 (99 sides, NVB resection; 31 sides, NVB preservation) and 83 (106 sides, NVB resection; 60 sides, NVB preservation) patients undergoing ORRP and RARP, respectively. The posterior sectors from the apex, mid, and base areas on each side were immunohistochemically stained with an nNOS antibody.ResultsOn the sides with NVB resection, there were no significant differences in the numbers of nNOS-positive nerves in any areas between the ORRP and RARP groups; however, on the sides with NVB preservation, the numbers of nNOS-positive nerves in the ORRP group were significantly higher than those in the RARP group at the apex (84.4 vs 59.2; P = .0028), mid (71.2 vs 52.4; P = .016), and base (148.0 vs 40.8; P <.001) areas. In 55 patients who were judged not to have severe erectile dysfunction before surgery and subsequently underwent nerve-sparing RP, there was a significantly inverse correlation between the total number of nNOS-positive nerves on both sides and the postoperative erectile function.ConclusionThese findings suggest that RARP might be suitable for performing precise nerve-sparing surgery compared with ORPP, particularly in the base area of the prostate and that the quantification of nNOS-positive nerves in surgical specimens could be a useful approach for predicting the postoperative erectile function.