Establishment of Novel Intraoperative Monitoring and Mapping Method for the Cavernous Nerve During Robot-assisted Radical Prostatectomy: Results of the Phase I/II, First-in-human, Feasibility Study.

Potency preservation often does not meet expectation despite nerve-sparing prostatectomy.

To set the protocol for intraoperative cavernous nerve monitoring and mapping during robot-assisted radical prostatectomy (RARP), and to evaluate its safety and clinical feasibility.

A prospective phase I/II, feasibility study was performed. A total of 30 patients with prostate cancer who underwent RARP at a high-volume tertiary academic hospital were enrolled.

Pudendal somatosensory evoked potential, bulbocavernosus reflex, spontaneous corpus cavernosum electromyography (CC-EMG), median nerve stimulation evoked CC-EMG, and neurovascular bundle (NVB)-triggered CC-EMG with various stimulation protocols were assessed during conventional RARP under total intravenous anesthesia with controlled muscle relaxation.

The primary endpoint was the completion rate of planned surgery and assessment. Adverse events, and erectile and urinary functions were evaluated within 1 yr. CC-EMGs were graded and correlated with functional outcomes.

The completion rate was 100%. Only one patient experienced adverse events, which were not related to study intervention. Grades of CC-EMGs including NVB-triggered CC-EMG before prostate removal were associated with baseline five-item International Index of Erectile Function (IIEF-5) score (grades 0-1, 4.6±2.7; grade 2, 13.2±6.8; grades 3-4, 16.6±5.9; p=0.003). Furthermore, grades of CC-EMGs including NVB-triggered CC-EMG after prostate removal were significantly associated with potency recovery (grade 0, 12.5%; grade 1, 0%; grade 2, 33.3%; grades 3-4, 100% at 12 mo; p=0.005) and postoperative IIEF-5 scores at all evaluation time points (grades 0-1, 2.6±2.8; grade 2, 4.3±5.8; grades 3-4, 15.7±11.0 at 12 mo; p=0.003).

We successfully established the protocol for safe intraoperative cavernous nerve monitoring and mapping using CC-EMG during RARP. Its grades were well correlated with erectile function.

In this first-in-human feasibility study, we successfully established the protocol for safe intraoperative cavernous nerve monitoring and mapping method during robot-assisted radical prostatectomy. The results were significantly associated with erectile function. Evaluation of clinical efficacy to preserve potency seems worthy of further optimization and investigation in confirmatory clinical trials.

European urology. 2019 May 15 [Epub ahead of print]

Won Hoon Song, Ju Hyun Park, Bum Sik Tae, Sung-Min Kim, Min Hur, Jeong-Hwa Seo, Ja Hyeon Ku, Cheol Kwak, Hyeon Hoe Kim, Keewon Kim, Chang Wook Jeong

Department of Urology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Urology, Pusan National University Yangsan Hospital, Pusan National University Colleage of Medicine, Yangsan, Republic of Korea., Department of Urology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Urology, Seoul National University Boramae Medical Center, Seoul, Republic of Korea., Department of Urology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Urology, Korea University Ansan Hospital, Korea University College of Medicine, Ansan, Republic of Korea., Department of Neurology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea., Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea., Department of Urology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea., Department of Rehabilitation Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea. Electronic address: ., Department of Urology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea. Electronic address: .

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