A randomized phase 3 study of intraoperative cavernous nerve stimulation with penile tumescence monitoring to improve nerve sparing during radical prostatectomy

Purpose: We determine if mapping of the cavernous nerve during radical prostatectomy using intraoperative cavernous nerve stimulation with tumescence monitoring results in improved erectile potency compared to conventional nerve sparing. Materials and Methods: A prospective, randomized, single blinded study was performed on 61 patients at 6 centers. Patients had elected to undergo nerve sparing prostatectomy and had normal preoperative erectile function documented by the Sexual Function Inventory Questionnaire (SFIQ) and RigiScan parallel to testing. Patients were randomized between conventional nerve sparing and nerve sparing assisted by the CaverMap Surgical Aid. In all patients neural continuity was assessed immediately after prostate removal by proximal cavernous nerve stimulation. All patients were blinded according to their allocation cohort. Results: At 1 year there was substantial improvement in erectile function in the CaverMap group as measured by RigiScan. This group had a mean of 15.9 minutes of greater than 60% nocturnal tumescence compared to 2.1 minutes in the conventional nerve sparing group (p <0.024). By SFIQ there was a nonsignificant trend to improved potency in the CaverMap group (71% versus 62%, p = 0.17). Of patients who had bilateral, unilateral and no response to stimulation after resection erectile function assessed by SFIQ recovered in 68%, 27% and 0%, respectively (p = 0.016). Conclusions: CaverMap assisted prostatectomy led to improved erectile function as assessed by RigiScan testing with no associated adverse events. A response to stimulation immediately after removal of the prostate accurately predicted return of erectile function.