Cavernosal nerve preservation during robot-assisted radical prostatectomy is a graded rather than an all-or-none phenomenon: objective demonstration by assessment of residual nerve tissue on surgical specimens

Abstract

Objective: To demonstrate the existence of different degrees of nerve sparing (NS) (graded NS) by comparing the surgeon's intent of NS with the residual nerve tissue on prostatectomy specimens.

Methods: We performed a prospective study of 133 consecutive patients who underwent robot-assisted radical prostatectomy in January and February of 2011. The surgeon graded the amount of NS intraoperatively independently for either side as follows: 1, no NS; 2, <50% NS; 3, 50% NS; 4, 75% NS; and 5, ≥ 95% NS. A pathologist who was unaware of the surgeon's score measured the area of residual nerve tissue on the posterolateral surface of the prostate.

Results: A greater NS score correlated significantly with a decreasing area of residual nerve tissue on the prostatectomy specimens (P < .001). Overall, the area of residual nerve tissue on the prostatectomy specimens was significantly different among the NS groups (P < .001). On specific intergroup analysis, significant differences were found in the area of residual nerve tissue on the prostatectomy specimens between the greater NS groups: NS score 3 versus 4, median 13 mm(2) (interquartile range [IQR] 7-23) versus 3 mm(2) (IQR 0-8; P = .01); NS score 4 versus 5, median 3 mm(2) (IQR 0-8) versus 0.5 mm(2) (IQR 0-2; P = .001).

Conclusion: Subjective NS classification using the surgeon's intraoperative perception correlated significantly with the area of residual nerve tissue on the prostatectomy specimens determined by the pathologist. It is possible to intentionally tailor the amount of NS performed at surgery. This finding demonstrates that NS is a graded rather than an all-or-none phenomenon that can even go beyond the traditional concept of complete, partial, or no NS.