An Operative and Anatomic Study to Help in Nerve Sparing during Laparoscopic and Robotic Radical Prostatectomy

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1 European Urology European Urology 43 (2003) An Operative and Anatomic Study to Help in Nerve Sparing during Laparoscopic and Robotic Radical Prostatectomy Ashutosh Tewari a,*, James O. Peabody a, Melissa Fischer a, Richard Sarle a, Guy Vallancien b, V. Delmas c, Mazen Hassan a, Aditya Bansal a, Ashok K. Hemal a, Bertrand Guillonneau b, Mani Menon a a Vattikuti Urology Institute, Henry Ford Health System, 2F One Ford Place, Detroit, MI 48202, USA b L Institut Mutualiste Montsouris, University Pierre & Marie Curie, Paris, France c UFR d Anatomie, University Pierre & Marie Curie, Paris, France Accepted 13 February 2003 Abstract Objective: To provide a detailed description of the steps involved in a laparoscopic radical prostatectomy in relation to the complex neurovascular anatomy of the male pelvis. Aim and hypothesis: We aimed at delineating the neurovascular anatomy to assist in nerve preservation during laparoscopic and robotic radical prostatectomies. Methods: A team of urologists and an anatomist performed anatomic dissections of 12 male cadavers using a combination of laparoscopic equipment, magnification, and open surgical dissection. Each step involved in laparoscopic prostatectomy was reviewed in relation to the possible impact the step could have on the neurovascular bundles. Results: Dissections were performed systematically to mimic various steps of laparoscopic and robotic prostatectomy. The neurovascular bundles were identified and correlated with video images of actual surgery. This enabled us to construct computer simulations and show the actual nerves on the operative pictures. We specially unraveled the relationship between neurovascular bundles and lateral pelvic and Denonvillier s fascias, both of which enclose and hide these important structures. The course of the bundles was traced from its origin at pelvic plexus to its distal course along the urethra. We also showed the important relationship between pelvic plexus ganglions and seminal vesicles to illustrate the vulnerability of these nerves to thermal, electrical and/or crush injury during seminal vesicle and prostatic pedicle dissections. The importance of additional fine neural plexus along the posterior and antero-lateral surface of the prostate was shown by both gross anatomical and microscopic images. The distal precarious location of the bundles was illustrated by dissections showing anteriorly lifted prostate. These anatomico-operative correlations have not been published for laparoscopic and robotic prostatectomies, which differ significantly in its visual angles, magnifications and sometimes three-dimensional (3D) visualization from its open counter part. Conclusion: Laparoscopic and robotic radical prostatectomy provides exposure and visualization of male pelvis not previously appreciated. It is only through a careful reexamination of the anatomy of the male pelvis, in the context of this new procedure, that the improvements in visualization and exposure benefit the surgeon. Our work provides a detailed map relating to operative steps to aid the surgeon in the performance of a nerve sparing robotic and laparoscopic radical prostatectomy. # 2003 Elsevier Science B.V. All rights reserved. Keywords: Prostate cancer; Robotics; Laparoscopic prostatectomy; Anatomic nerve sparing radical prostatectomy; Nerve sparing * Corresponding author. Tel. þ ; Fax: þ address: atiwari@hfhs.org (A. Tewari) /03/$ see front matter # 2003 Elsevier Science B.V. All rights reserved. doi: /s (03)

2 A. Tewari et al. / European Urology 43 (2003) Introduction More than 170,000 men in the United States were diagnosed with prostate cancer in The goal of effective cancer screening is to identify patients with more localized, and thus more potentially curable disease. Radical retropubic prostatectomy offers an effective cure [1 4], but can be associated with postoperative morbidities, including erectile dysfunction and incontinence [5 7]. Sexual function can often be maintained by nerve sparing with the anatomic prostatectomy developed by Walsh [8 10] and others [11 15]. However, the results regarding potency preservation published in the literature by many centers are not satisfactory [5 7]. Many factors influence postoperative potency, including preoperative erectile function, patient age, extent of disease, experience of the surgeon, and anatomic variation. Identifying and sparing the neurovascular bundle (NVB) on one or both sides is crucial in maintaining erectile function. Several excellent monographs, textbooks, and artist drawn figures explaining the detailed course of the neurovascular bundles are available based on the initial anatomical dissections [8 10,16,17]. In recent years some centers are attempting nerve sparing anatomic prostatectomy using conventional and robotic-assisted laparoscopic approaches [18 33]. The surgical steps for these minimally invasive approaches differ significantly from the conventional radical prostatectomy for which most existing anatomical descriptions have been done. Both laparoscopic and robotic approaches differ from open prostatectomy in terms of visualization, magnification, and most importantly, procedure steps. Laparoscopic and robotic prostatectomies are performed in an antegrade manner, while conventional radical retropubic prostatectomy is often performed in a retrograde manner (i.e. transection of the urethra prior to bladder neck disconnection from prostate). A detailed anatomical map of the neurovascular bundles from the laparoscopic perspective is currently lacking. While artist drawn figures are adequate for the open surgery which benefits from both vision and tactile sense, they are not as useful during laparoscopic and robotic procedures because (a) they were not drawn with laparoscopic approach in mind and (b) the magnification and three-dimensional (3D) stereoscopic vision of robotic cameras actually require seeing these important structures through the lenses rather than surgical loupes or naked eye. Therefore we undertook this anatomical study (with the help of an anatomist) to unravel the course of neurovascular bundles and superimposed the images on the intra-operative captures. Our goal was to develop a clear map to assist in the performance of nerve sparing laparoscopic or robotic radical prostatectomy, with good Fig. 1. Overview of neuroanatomy of pelvic, vesical and prostatic plexus.

3 446 A. Tewari et al. / European Urology 43 (2003) Fig. 2. (A) Anatomic dissection showing exact course of neurovascular bundles, pelvic plexus and its relation with seminal vesicles and prostate. The neurovascular bundle is clearly visible once the periprostatic fascia is removed. (B) Anatomic dissection from the posterior view (looking through pouch of Douglas) showing location of the seminal vesicles, pelvic plexus and rectum. (C) Intra-operative picture showing location of the ganglions in relation to the seminal vesicles.

4 A. Tewari et al. / European Urology 43 (2003) anatomical landmarks adapted for this new surgical approach. 2. Materials and methods The data for this analysis was acquired by anatomic study of 12 fresh male cadavers of more than 50 years of age. The dissections were performed using laparoscopic camera, light source, video monitor and hand equipments (CIRCON ACMI TM Corporation). Later the courses of the nerves were further traced by open dissection using 2.5 surgical loops and an operating microscope. The nerve tissue was finally confirmed by histopathological studies. The dissection was planned to mimic actual surgical procedure. The technique of antegrade laparoscopic and robotic nerve sparing has been described in Section 3 [23,24,32,33]. This differs significantly from classical open nerve sparing during which the lateral pelvic fascia is incised and bundles are dropped before actual urethral transection [34]. Some surgeons have also performed antegrade nerve sparing much like laparoscopic and robotic prostatectomies [35]. The detailed review of open nerve sparing is beyond the scope of this article and reader is referred to several excellent texts Pelvic neurovascular anatomy An artist drawn schematic picture of the origin and course of the neurovascular bundles is illustrated in Fig. 1. Additional anatomic, microscopic and intra-operative pictures supplement these figures (Figs. 2 8). Anatomically, the spinal nuclei involved in the control of erectile function are located at the S2 to S4 level. These axons travel ventrally to join the axons of the nuclei for the bladder and rectum to form the sacral visceral efferent fibers. These fibers join the sympathetic fibers to form the pelvic plexus, an extension of inferior hypogastric plexus. The pelvic plexus lies on the anterolateral wall of the rectum. Each ganglion contains approximately 20 nerve cell bodies. The superior part of the aggregate of the nerve cells is called the vesical plexus. The inferior part of the pelvic plexus is the prostatic plexus. The NVB arises from the prostatic plexus, which is enclosed between the two layers of periprostatic fascia. The prostatic plexus and the NVB is about 1.5 mm posterolateral to the prostate at the base and about 3 mm at the apex. The anatomic relationships between the prostate, bladder, seminal vesicles, rectum, pubo-prostatic ligaments, symphysis pubis, venous plexus, prostatic apex, urethral sphincter, ureters, regional vasculature and nerves were carefully dissected and recorded on digital video (DV) for future evaluation. We also recorded the actual surgical procedure using either Stryker Endoscopes threechip camera (Stryker Endoscopes 1, Santa Clara, CA, USA) or da Vinci stereoscopic camera attached to a Sony 1 Digital camcorder (Sony DCR-VX2000 Digital Video Handycam 1 Camcorder, New York, NY, USA). This equipment allowed for digital video recording at a 530 lines horizontal resolution and 12 optical/48 digital zoom video capture. The images were processed on a Pentium III MHz, Dell Computer Corporation computer with 500MB RAM, 32MB video RAM and 200GB Hard Drive. Computer simulations were done using anatomic images and volume rendering modeling algorithms to serve as intra-operative guide to assist in nerve sparing. 3. Results The relationship between various anatomic structures is described herein Pelvic and prostatic plexus As seen in Figs. 1 and 2, the pelvic plexus is a retroperitoneal structure located on the lateral wall of the rectum. The mid-point of the plexus corresponds approximately to the tip of the seminal vesicle. The cavernous branches travel anteriorly on the surface of the rectum. As seen in Fig. 3, lying on the surface of rectum we noted cross-connections between branches of pelvic plexus of two sides (Figs. 3 and 8). These Fig. 3. Oblique view: left side of apex showing delicate and veiled nature of the neurovascular bundles, nerve plexus and cross-communications (white arrows).

5 448 A. Tewari et al. / European Urology 43 (2003) communications run within the fascial layer and their physiologic significance has not been studied Relationship with the seminal vesicles At the side of seminal vesicles the cavernous branches coalesce to form a more compact (approximately 4 6 mm) bundle and travel anteriorly in a groove between rectum and prostate (Figs. 2A C and 3). Fig. 2B and C delineates the relationship between the pelvic plexus and seminal vesicles as approached from the pouch of Douglas. The posterior face of the seminal vesicle is never vascularized Fig. 4. Anatomic dissections showing the lateral pelvic fascia from various angles: (A) lateral surface of the prostate showing small and large nerves (black arrows); (B) undersurface of the prostate showing Denonvillier s fascia and nerves.

6 A. Tewari et al. / European Urology 43 (2003) Fig. 5. Microscopic images of the nerves in the lateral pelvic fascia (brown structures) (note the small nerves posterior and antero-lateral to the prostate): (A) low magnification; (B) medium magnification; (C) high magnification. and the plane between the posterior layer of the Denonvillier s fascia and the seminal vesicle could be easily developed. Vessels are approaching the seminal vesicle laterally, and there is often one artery that travels on the anterior surface of the seminal vesicle between the superficial layers of the Denonvillier s fascia Technical points These nerves and ganglions are likely to get injured during dissection of seminal vesicles and control of prostatic pedicles. The key is to get to the surface of seminal vesicles and avoid dissecting outer layers. Furthermore, sharp dissection rather than coagulation should be used in this area.

7 450 A. Tewari et al. / European Urology 43 (2003) Fig. 6. Computer enhanced intra-operative relationship between the lateral pelvic fascia, Denonvillier s fascia, and prostate and neurovascular bundles: (A) triangle of lateral pelvic fascia, prostate and Denonvillier s sheet and their relationship with nerves; (B) relationship between pelvic plexus and neurovascular bundles to the left prostatic pedicle Neurovascular bundle Description The classical description of the neurovascular bundles states that there is one main nerve on either side of the prostate, which is enclosed in fascial sheaths and is accompanied with prostatic vessels. We noted that in addition to these main bundles, there are several smaller nerves, which ramify in the prostatic and Denonvillier s fascia (Fig. 5). The exact physiologic role of these smaller nerves in the erection is not well defined but they do exist and may contribute to the neural impulses to the cavernous tissue Periprostatic fascia As seen in Figs. 4 6, the neurovascular bundles are enclosed within the layers of the periprostatic fascia. This fascia has two flimsy layers, which splits posteriorly to enclose the neurovascular bundle. These layers of periprostatic fascia fuses with the anterior layer of

8 A. Tewari et al. / European Urology 43 (2003) posterior wall of this triangle is formed by the anterior layer of the Denonvillier s fascia. The medial wall of the triangle (prostatic fascia) is intimately attached to the prostatic capsule (Fig. 6A). This triangular space is wide near the base of the prostate and becomes narrower near the apex. The neurovascular bundle is located in this triangular space, covered by superficial layers of Denonvillier s fascia, that fuse with the posterior limits of levator fascia. Along the course of the bundles, micropedicles (tiny arteries, veins, and nerves) are found that supply, in no consistent pattern, the adjacent prostate capsule and tether the bundles to the postero-lateral surface of the prostate (see Fig. 4). Fig. 7. Anatomic view of nerves and prostate at the apex. (Note how close to the urethra bundles come at the apex.) Denonvillier s fascia lateral to the prostate in a manner to enclose a potentially triangular space containing the neurovascular bundles. The inner layer of periprostatic fascia (also called as the prostatic fascia) forms the medial vertical wall of this triangle; the outer layer of periprostatic fascia (also called as lateral pelvic fascia) forms the lateral wall, and the Technical points In order to perform nerve sparing, operator needs to reflect the lateral pelvic fascia off the prostate. Meticulously controlling the prostatic pedicle proximally and entering the triangular space between lateral pelvic fascia, Denonvillier s fascia and prostate best preserves the nerves. Incising the lateral pelvic and Denonvillier s fascia the triangular space is entered. A fatty layer is seen which is a hallmark of proper plane of dissection. In order to improve the nerve preservation, attempt should be made to leave maximum amount of surrounding fascial tissues Apical course Near the apex of the prostate, the neurovascular bundles are covered with fascial layers and are approximately 3 mm away and occupy 5 and 7 o clock position around the urethra (Figs. 7 and 8). Fig. 8. Final view showing computer enhanced location of the neurovascular bundles following radical prostatectomy.

9 452 A. Tewari et al. / European Urology 43 (2003) Technical points The neurovascular bundles are at risk during urethral trsansection and anastomosis. This risk can be minimized by visual appreciation of the nerves in a bloodless field and avoidance of electro-cautery in the vicinity of the nerves. Inadvertent suture bites should be avoided by exercising caution near the nerves and placing the sutures under vision Relationship to the rectum The course of the NVB is fairly consistent, despite variations in prostate size. The NVBs form the sides of an isosceles triangle (Figs. 7 and 8) with the bladder at the base and the urethra at the apex. The triangle is essentially the same size and configuration no matter what size prostate is lifted away from the bundles. The cross-communicating fibers are located underneath the fascia, on the surface of rectum, and form a fine meshwork of neural fibers communicating bilaterally Technical points Dissection in the proper plane and keeping the operative field dry will both help in avoiding inadvertent injury to rectum during posterior dissection. 4. Comments Our study was undertaken to create a map of the NVB, with the goal to improve urologists understanding of pelvic anatomy from the new vantage point provided by the laparoscopic approach. Based on our dissection, the location of the pelvic plexus, course of the NVB and its relationship with seminal vesicle, lateral prostatic fascia and prostate were clearly identified. Keeping these relationships in mind, our discussion will now focus on the specific stepsofalaparoscopic prostatectomy. Most centers performing laparoscopic radical prostatectomy begin the procedure by dissecting the seminal vesicles through the cul-de-sac between the bladder and rectum [21,24,28,36,37] or by mobilizing the bladder [21,30 33,38,39]. The remaining steps are more or less similar and include development of the space of Rietzius, exposure of prostatic apex and endopelvic fascia, control of dorsal venous plexus, transection of the bladder neck, dissection of seminal vesicles, lateral pedicle control, nerve sparing, apical dissection, incision of dorsal venous complex and urethra and finally urethro-vesical anastomosis. The pelvic, vesical, and prostatic plexuses are at risk of transection, clipping or coagulation injury during posterior dissection through the recto-vesical cul-desac. As seen in Figs. 1, 2 and 4, the bulk of the pelvic plexus and its important branches are located lateral and posterior to the seminal vesicles. Therefore the seminal vesicles should be used as an intra-operative landmark to avoid injury to the pelvic plexus when ligating the posterior pedicle. The proponents of retrovesical dissection [21,24,28,36,37] suggest that since the NVBs are very close to the tip of the seminal vesicle, the initial dissection behind the bladder leaves a bloodless field, which makes the neurovascular dissection easier and more accurate. However, even during the extraperitoneal prostatectomy, neural injury can be avoided by precise dissection and control of the individual vessels close to the seminal vesicles [31,32]. Next several steps, such as bladder mobilization, exposure of pubo-prostatic ligaments, control of dorsal venous plexus and transection of anterior bladder neck are relatively safe from the nerve sparing perspective. It is important to note that the control of the Santorini plexus indirectly helps in satisfactory nerve sparing by ensuring bloodless field and good visualization of the anatomical landmarks. Caution is needed following incision of the posterior bladder neck. The pelvic plexus is located laterally, and too zealous a dissection in this direction may place few pelvic, vesical or prostatic plexus fibers at risk. The vas and seminal vesicles are next dissected and require sharp incision of the superficial layer of Denonvillier s fascia. The tip of the seminal vesicles often is tethered postero-laterally due to the vessels supplying the vesicles and the vas. Traction on the seminal vesicles during this dissection may tent the branches of pelvic plexus medially. Therefore these vessels should be controlled on the surface of seminal vesicles. As mentioned before, the key to successful nerve sparing requires meticulous dissection, clear visualization, control of individual vessels on the surface of the seminal vesicles and avoiding electro-cautery laterally. The control of lateral pedicles also is a precarious step, because the pelvic plexus lies postero-laterally. Staying close to the prostatic surface avoids injury to these nerves. At this stage some surgeons incise the levator fascia above the neurovascular bundles and enter the triangular space. Since the triangular space containing the neurovascular bundles is more prominent at the prostatic base rather than the apex, the antegrade approach can easily develop plane of dissection within the triangle leaving the medial fascia attached to the prostate. This dissection may not be easy in retrograde approaches of laparoscopic prostatectomy, as the triangle is not so well developed at the apex [39,40]. The neurovascular bundle is then reflected laterally and incision is completed through the facial layers to leave

10 A. Tewari et al. / European Urology 43 (2003) the most of Denonvillier s fascia on the posterior surface of the prostate while leaving the minimal, lateral most fibers of the Denonvillier s fascia around the neurovascular bundles. Others make initial cut in the Denonvillier s fascia parallel to the neurovascular bundles and thus enter the triangular space medial to the bundles. The incision of the levator fascia is next performed to reflect the neurovascular bundles laterally. In the patients in whom pedicle is long and mobile, the posterior incision first is a good option, but sometime, when the posterolateral pedicle is tight, we have no access to Denonvillier s fascia, and thus the incision of the periprostatic fascia is more reasonable. Once the correct plane is entered, the majority of the dissection occurs in a relatively avascular plane. Sometimes there are two to three micropedicles entering the capsule of the prostate medially [8,41 43]. They require sharp transection and hence bleed minimally. We avoid any clipping or use of electro-cautery because the bleeding is often self-limiting. Sometimes, one could find a small lateral pedicle coming from the NVB and penetrating the prostate close to its apex. This pedicle should be controlled, with clip or accurate coagulation, far from the bundle [41 43]. The next stage of the procedure involves the apical dissection, where the NVB lies more laterally and are at risk for damage during both the urethral transection and anastomosis. Keeping the NVBs in view at all times and keeping the field dry can avoid these pitfalls. The use of a magnified view through the laparoscopic camera or enhanced 3D visualization dramatically improves the identification of various anatomic structures. When performed properly, the laparscopic procedure allows the surgeon to appreciate the pulsation of the arterial components of the bundle. Again, the improvements in visualization provided by both the magnification and a bloodless field, cannot be underemphasized. At the end of a successful nerve sparing prostatectomy, if the field is dry, we can often see pulsations of the vessels in the NVB and may use this finding as a surrogate for the integrity of the nerves. It is our hope that the anatomic details provided here will assist surgeons in recognizing and thus sparing the neurovascular bundles. 5. Conclusion Laparoscopic and robotic prostatectomies provide a view of the male pelvis not previously appreciated in open surgery. Vantage point, magnification, threedimensional imaging, and improved hemostasis are all factors responsible for the better visualization encountered in laparoscopic and robotic prostatectomies. While logic dictates that a superior view should translate into the ability to perform a more meticulous dissection, unless surgeons are familiar with the new perspective provided by laparoscopic and robotic optics, outcome improvements will fail to occur. By providing a step-by-step, anatomic outline of pelvic anatomy from the laparoscopic perspective, we hope to shorten the learning curve, and assist surgeons undertaking the Table 1 Critical maneuvers in nerve sparing Step of operation Neurovascular structure at risk Critical maneuvers Retrovesical dissection Pelvic, vesical and prostatic plexus (Figs. 1 and 2) No dissection lateral to the seminal vesicles, and no excessive use of cautery or clips. Anterior dissection If the dissection is carried too far laterally, Avoid dissecting too deep in the groove between prostate and rectum. the nerves may be injured Control of dorsal venous complex None This is an important step due to its effect on hemostasis and visualization. Poor visualization is detrimental for nerve sparing. Anterior bladder neck transection None None. Posterior bladder neck transection Laterally pelvic, vesical and prostatic plexus are located deep to the bladder neck Dissection under vision and with meticulous hemostasis. Avoid excessive incision lateral to the bladder neck. Seminal vesicle dissection Pelvic, vesical and prostatic plexus (Fig. 2B and C) No dissection lateral to the seminal vesicles, and no excessive use of monopolar cautery. Use accurate control (clips or bipolar cautery). Control of pedicles Vesical and prostatic plexus and proximal part of neurovascular bundles (Fig. 6B) Meticulous dissection to expose the blood supply and individually control them using clips applied or bipolar current close to the prostate. Avoid monopolar cautery. Lateral dissection Neurovascular bundles (Figs. 4 8) Approach through the triangle and leave a thick sheath of lateral pelvic fascia (see Comments). Urethral transection Neurovascular bundles (Fig. 8) Transection under vision. Anastomosis Neurovascular bundles (Fig. 8) Anastomosis should be performed under vision without any pool of blood. Be careful for the posterior stitches, particularly at 5 and 7o clock.

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