Partial Neurovascular Bundle Sparing During Robot-Assisted Radical Prostatectomy

Abstract

In modern times, excision of neurovascular bundles is less common. Nomograms can help predict when to preserve nerve bundles, but often the concern is only slight, or implied on an MRI exam. When there is dominant disease on one side, an oncologically safe option is to back off a few millimeters from the capsule to increase margin clearance but preserve a reasonable amount of tissue for functional recovery. In this chapter, we consider the anatomic landmarks for partial or incremental nerve preservation, and outcomes for quality of life and cancer control.

Editor’s Comments—Matin and Orvieto

In the 1990s, Christopher Wood designed a single center study at MD Anderson Cancer center to evaluate the sural nerve graft concept as a phase II randomized trial. Patients received unilateral nerve sparing plus contralateral non-nerve sparing with or without a sural nerve graft. Ultimately, the trial was reported as a negative result at the time of an interim analysis [36]. If you look at the details of the report, a number of patients were selected for unilateral nerve sparing surgery on the basis of three cores of cancer on one side—even if they were Gleason 3 + 3 to 3 + 4 range. In modern times, these are all performed with attempted bilateral nerve sparing, and the higher volume tumors are now imaged with endorectal coil MRI and also selected for bilateral nerve sparing if the images are normal or partial nerve sparing as reported by Matin and Orvieto if the images, clinical staging, or intraoperative findings are concerning for extra prostatic extension. Pugh et al. [37] looked at our MD Anderson Cancer Center experience with MRI imaging in intermediate risk and found that with an organ confined result on MRI and clinical T1c staging, then >95 % of cases were either pathologically organ confined or had at most 2 mm of extraprostatic extension from the capsule. Thus, the concept of incremental/partial nerve sparing with imaging has been popular in our center, and described by other authors as reviewed by Matin/Orvieto in the context of “graded” nerve sparing.

As a case example, a 74 year old presented to our center with a cT2a exam, PSA of 5.6, and 12 core biopsy showing eight cores of cancer, including two cores of Gleason 8 at the left mid and left apex biopsies. An MRI is shown in Fig. 7.1 supporting apical disease but organ confined. He had a SHIM score of 21 and AUA score of 8. He elected robotic surgery and was selected for right nerve sparing and left partial nerve sparing. The following Figs. 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, and 7.10 demonstrate the surgical technique, imaging, and pathology. His surgical pathology showed pT3a Gleason 4 + 3, negative margins and nodes (22 total). He reached an undetectable PSA but by 9 months it rose to 0.5 at which time he elected salvage radiation therapy. He had recovered urinary continence prior to salvage radiation and maintained it but had not regained potency. He is disease free with additional 2 years of follow-up.

Fig. 7.1

(a, b) A T2 weighted endorectal coil MRI image shows an apical lesion (a) with restricted diffusion on the map (b). The image turned out to be a false negative with the finding of pT3a disease, but the margins were not compromised with partial excision planed based upon the cT2a exam and multi-core Gleason 8 biopsies

Fig. 7.2

The right nerve was spared and you can see the base capsular surface well defined as the pedicle is being clipped and divided

Fig. 7.3

In this case, we used a method of full mobilization of the prostate with the diseased side sequenced last. The DVC was divided and the urethra divided. This allows additional rotation and orientation to plan and execute the partial nerve spare on the left

Fig. 7.4

The prostate can be rotated right and the left nerve spare setup

Fig. 7.5

The left partial nerve spare is exposed. The solid line would be a nerve sparing plane. The dashed line would be an incremental nerve spare with the arrows showing the discretionary amount of tissue that could be spared or taken depending upon imaging and surgeon judgment. The dotted line would the a non-nerve sparing plane

Fig. 7.6

Planes of nerve sparing from Salonia et al. [38]

Fig. 7.7

Planes of nerve sparing as depicted by Hinata et al. [39]

Fig. 7.8

The partial nerve sparing plane is sharply cut down and bleeders later oversewn or briefly sealed with the bipolar tip

Fig. 7.9

With the DVC and urethra previously cut, the apex can rotate nicely and the partial plane maintained around the apical corner. The bundle of tissue at the tip of the scissor remains the last division before the gland is freed

Fig. 7.10

The histopathology shows extraprostatic extension (black arrows) but not touching the inked margin (green arrows). Below—tumor cells touching fat are indicative of pT3a stage. Images courtesy Patricia Troncoso

In summary, the modern approach to radical prostatectomy continues to emphasize maximal feasible nerve sparing to improve quality of life. Incremental nerve sparing is an option and imaging can assist. Full wide excision of a nerve bundle is less common than in the 1990s. An alternate approach is illustrated by the Martini group that uses near universal nerve sparing with frozen section analysis rather than imaging or nomograms with planed incremental nerve excision.