Anatomic grading of nerve sparing during robot-assisted radical prostatectomy

Abstract

Background: Because of the lack of intraoperative visual cues, the amount of nerve sparing (NS) intended by the surgeon does not always correspond to what is actually performed during surgery.

Objective: Describe a standardized NS grading system based on intraoperative visual cues.

Design, setting, and participants: A total of 133 consecutive patients who underwent robot-assisted radical prostatectomy (RARP) by a single surgeon were evaluated. The surgeon intraoperatively graded the NS independently for either side as follows: 1=no NS; 2=<50% NS; 3=50% NS; 4=75% NS; 5= ≥ 95% NS.

Surgical procedure: RARP; detailed description of a five-point NS grading system.

Measurements: The area of residual nerve tissue on prostatectomy specimens was compared with the intraoperative NS score (NSS). The rate of positive surgical margins (PSMs) according to the NSS is also reported.

Results and limitations: In all, 52.6% of operated sides (140 of 266 sides) had NSS 5, 30.1% (80 of 266) had NSS 4, 2.3% (6 of 266) had NSS 3, 13.2% (35 of 266) had NSS 2, and 1.9% (5 of 266) had NSS 1. The area of residual nerve tissue was significantly different among the different NSSs: median area (interquartile range) for NSS 5: 0.5 (0-2) mm(2); for NSS 4: 3 (0-8) mm(2); for NSS 3: 13 (7-23) mm(2); for NSS 2: 14 (8-24) mm(2); and for NSS 1: 57 (56-165) mm(2) (p<0.001). Overall, 9.02% of the patients (12 of 133 patients) had a PSM, with 8.3% (9 of 108) for pT2 and 12% (3 of 25) for pT3. Side-specific PSMs according to NSS were 3.6% (5 of 140) for NSS 5, 7.5% (6 of 80) for NSS 4, 16.7% (1 of 6) for NSS 3, 5.7% (2 of 35) for NSS 2, and 0% (0 of 5) for NSS 1. A limitation of our study is that the key anatomic landmarks are not recognizable in every case, and this technique might not be easy to perform during the early learning curve.

Conclusions: We believe that the visual cues exposed in this article will help surgeons achieve more consistent NS during RARP.