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Can intraoperative nerve monitoring improve functional outcomes after unilateral- or non-nerve-sparing robot-assisted radical prostatectomy – a randomized clinical trial

Introduction & Objectives

Damage to the branches of the pudendal nerve that innervate the external urethral sphincter (EUS) is a factor in the development of urinary incontinence after robot-assisted radical prostatectomy (RARP). They are located lateral to cavernous nerves and are prone to injury during unilateral- or non-nerve-sparing surgery. We investigated whether nerve identification can prevent nerve damage with a subsequent positive effect on functional outcomes.

Materials & Methods

Ethical approval was obtained and men scheduled to unilateral- or non-nerve-sparing RARP were randomized (1:1) to standard RARP (CTRL) or intraoperative nerve monitoring (INT) via the PROPEP® system. Two electrodes are inserted in the EUS and the Maryland forceps convey an electric impulse. When a nerve that innervates the EUS is located, an action potential is seen on the robot console screen and an external monitor. Subsequently, the area can be spared during dissection. The primary outcome was the International Consultation on Incontinence Questionnaire (ICIQ) score at 12 months. Secondary endpoints included continence at 12 months defined as <8 grams on a 24-hour pads test or the use of 0 pads per day and the answer “never” to the first ICIQ question regarding incontinence frequency. Also, the international prostate symptom score (IPSS), the Erection Hardness Score (EHS), and sexual activity at 12 months were analyzed. Outcomes were analyzed using regression with robust variance estimation.


From 2018-2022, 100 men were randomized. A positive nerve signal was found in all INT-group participants. There were no differences in baseline characteristics between the groups. ICIQ was 5.37 (INT) versus 5.66 (CTRL) (95% CI [-2.57;1.99], p=0.8). Continence was 63.4% (INT) vs. 63.4% (CTRL) (95% CI [-21.43;21.43], p= 1). IPSS score was 5.93 (INT) vs. 5.39 (CTRL) (95% CI [-0.91;1.98], p= 0.46). EHS score was 0.95 (INT) vs. 1.18 (CTRL) (95% CI [-0.73;0.29], p= 0.39). Sexual activity was 61% (INT) vs. 57.5% (CTRL) (95% CI [-18.5;25.5], p= 0.75).


Identification of the somatic nerves that innervate the EUS did not improve functional outcomes compared to standard RARP.