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Keywords:

  • anatomy;
  • prostate cancer;
  • prostatectomy;
  • robotic surgery

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Basic concept of neuroanatomy for radical prostatectomy
  5. Anatomical findings according to each procedure in state-of-the-art RALP
  6. Conclusion
  7. Conflict of interest
  8. References

Robotic-assisted laparoscopic prostatectomy has consolidated the position of surgical treatment for localized prostate cancer in the USA. In a few years, it is expected to spread rapidly worldwide. However, surgical anatomy has trailed the advance in surgical techniques of robotic-assisted laparoscopic prostatectomy. Therefore, we reviewed the recent literature, which sometimes refutes the established consensus on pelvic anatomy, for the state-of-the-art technique. We also describe the anatomical findings for each basic step during robotic-assisted laparoscopic prostatectomy, and show evidence-based surgical techniques. Of course, these findings will also be useful for radical retropubic, perineal and conventional laparoscopic prostatectomy. Surgical anatomy should always be developing and changing with advances in surgical approaches.


Abbreviations & Acronyms
ANP =

accessory distal neural pathways

APA =

accessory pudendal artery

BL =

bladder

CG =

Cowper's gland

DTP =

deep transverse perineal muscle

DVF =

Denonvilliers' fascia

ED =

erectile dysfunction

EPF =

endopelvic fascia

FLA =

fascia of the levator ani

HGN =

hypogastric nerve

LA =

levator ani

LM =

longitudinal muscle of the rectum

LPF =

lateral pelvic fascia

LRP =

laparoscopic radical prostatectomy

MPM =

multiphoton microscopy

nNOS =

neuronal nitric oxide synthase

NVB =

neurovascular bundle

PHI =

peptide histidine isoleucin

PNB =

predominant neurovascular bundle

PNP =

proximal neurovascular plate

PPL =

pubo-prostatic ligament

PPM =

pubo-perinealis muscle

PR =

prostate

PSN =

pelvic splanchnic nerve

RALP =

robotic-assisted laparoscopic prostatectomy

REC =

rectum

RRP =

radical retropubic prostatectomy

RS =

rhabdosphincter

RUM =

recto-urethralis muscle

SV =

seminal vesicle

TH =

tyrosine hydroxylase

UR =

urethra

Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Basic concept of neuroanatomy for radical prostatectomy
  5. Anatomical findings according to each procedure in state-of-the-art RALP
  6. Conclusion
  7. Conflict of interest
  8. References

Almost all urologists consider that human anatomy has already been completely elucidated. However, we have not yet reached a consensus on many anatomical structures around the urological organs. In particular, surgical anatomy around the prostate, which provides a road map for radical prostatectomy, remains obscure. Surgical anatomy refers to the relative positioning of each structure in the surgical field. If a new method or new approach to a surgical procedure is developed, a new surgical anatomy should also be developed.

The state-of-the-art radical prostatectomy is the RALP. RALP using the da Vinci surgical system started in 2000,1 and has spread rapidly, mainly in the USA. Now, it has become the established surgical treatment for localized prostate cancer in the USA.2 The magnified 3-D view, useful scissors with multi-joints, and the ease of the manipulation of the da Vinci system have provided surgeons with exceptional detail of the pelvic anatomy and made radical prostatectomy a minimally invasive surgery. As a result, RALP could be an epoch-making surgical procedure with which we could achieve the three competing goals of radical prostatectomy; that is, cancer control, urinary continence and erectile function.3

We consider that surgical anatomy has trailed the advances in surgical techniques in RALP, even though the surgeon can identify the delicate structures surrounding the prostate. It is only natural that the anatomical findings of the 1980s4 cannot facilitate the state-of-the-art RALP. In the present review, we show new anatomical findings around the prostate for radical prostatectomy, especially that using RALP. Of course, these findings will also be useful for RRP, perineal and conventional LRP.

Basic concept of neuroanatomy for radical prostatectomy

  1. Top of page
  2. Abstract
  3. Introduction
  4. Basic concept of neuroanatomy for radical prostatectomy
  5. Anatomical findings according to each procedure in state-of-the-art RALP
  6. Conclusion
  7. Conflict of interest
  8. References

Conventional concept

Using the dissection of male fetuses and newborn cadavers, Walsh and Donker first showed the course of the cavernous nerve.4 This milestone work was confirmed by Lepor et al., postulating a macroscopic concept of the NVB expected to contain the cavernous nerve.5 Subsequently, in radical prostatectomy, urological surgeons have tried to identify the “cord-like NVB” at the lateral aspect of the prostate. However, little histological or physiological investigation was carried out to verify that the NVB identified at surgery really included the cavernous nerve.

Recent concept

Macroanatomy

Recently, there have been observations that refute the idea that the cavernous nerve is always within the NVB. Costello et al.6 noted that the NVB was composed of nerve fibers heading toward the rectum, the levator ani muscle, the prostate and the cavernous tissues. Our group also showed that the so-called NVB cannot include the cavernous nerve in its entire course.7,8 The cavernous nerves were consistently included in the caudal components of the PSN, which joined the surgically created NVB at levels inferior or distal to the bladder–prostate junction in a spray-like arrangement. Correctly, there is no histological bundle-like structure at the posterolateral aspect of the prostate.7

Functional anatomy

It is very complicated to identify the contribution of each peripheral autonomic nerve fiber in the pelvis. Generally, the HGN was thought to be formed by sympathetic nerve fibers, and the PSN by parasympathetic nerve fibers. However, recent studies showed colocalization of the sympathetic and parasympathetic neurons in pelvic ganglia and macroanatomical neural units.9,10 If this is true, the concept of nerve-sparing radical prostatectomy might be more complicated. We examined the distribution of the sympathetic and parasympathetic ganglion cells in the pelvis.11 Although sympathetic ganglion cells were thought to exist above the pelvis except for the sacral sympathetic trunk, many actually existed in the pelvis. Interestingly, anti-TH-positive (as sympathetic marker) and anti-PHI-positive (as parasympathetic marker) cells intermingled and coexisted in individual ganglion cell clusters in the male pelvis (Fig. 1). Is the conventional understanding about the functional anatomy of the autonomic nerve fibers completely incorrect? The proportion of TH-positive sympathetic ganglion cells were examined in each neural component in the pelvis (Table 1). As expected, there were numerous TH-positive ganglions in the sacral sympathetic trunk and HGN. However, the TH-positive rate, even in the PSN, was 36%, which is thought to be a result of the parasympathetic nerve. Consequently, the usual simple classification of pelvic nerve components as “sympathetic hypogastric nerve” or “parasympathetic pelvis splanchnic nerve” might distort the understanding of autonomic physiology, and could impede the correct performance of nerve-sparing radical prostatectomy.

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Figure 1. Immunohistochemistry of a ganglion attached to the posterolateral surface of the prostate. (a) Tyrosine hydroxylase positive and (b) peptide histidine isoleucine positive cells coexisted in the same ganglion.

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Table 1.  Distribution of TH-positive sympathetic ganglion cells in the male pelvis
Neural componentTH-positive ratio in a single cadaver (mean)
Sacral sympathetic trunk (%)87–95 (90)
Along the hypogastric nerve (%)20–83 (62)
Pelvic plexus (%)27–78 (58)
NVB (%)16–54 (46)
Along the PSN (%)13–83 (36)
Nerve mapping during radical prostatectomy

It is impossible to clearly identify macroanatomically each nerve fiber responsible for urinary continence or erectile function in the surgical field. Using intraoperative electrical stimulation with simultaneous measurement of intracavernous and intraurethral pressure, we tried to elucidate the distribution of these nerve fibers.12 The course of the cavernous nerves did not always agree with the surgically identified neurovascular bundle. The distribution of cavernous nerves was wider than that of the neurovascular bundle, and the surgically identified neurovascular bundle contained nerve fibers contributing to urinary continence. We also examined the interindividual variation in the distribution of cavernous nerve fibers using a similar technique. Distribution of the cavernous nerves in a bundle-like formation was considered to account for 30%, whereas a plate-like formation accounted for 70%.13

In contrast, Yadav et al. reported a new method to examine the distribution of periprostatic nerve fibers using advanced technology.14 They explored MPM for real-time tissue imaging of the prostate and periprostatic neural tissue in a male Sprague–Dawley rat model. The unique advantage of this technique is the acquisition of high-resolution images without any extrinsic labeling agent and with a minimal phototoxic effect on tissue.

Trizonal concept

Background

Although the anatomical findings of the 1980s were milestones contributing to radical prostatectomy, those findings do not really facilitate state-of-the-art RALP, because the basic concept of pelvic neuroanatomy has been evolving as aforementioned. In the classical concept, neuroanatomy for nerve-sparing radical prostatectomy has been described in a limited area. However, we should understand pelvic neuroanatomy in a wider area. Additionally, because the approach to the prostate is quite different from RRP; that is, an antegrade approach, we need to understand the anatomy around the proximal and posterior aspect of the prostate.

Furthermore, the cavernous nerve itself is assumed to be very fine and have a small volume at the apex of the prostate or penile hilum.15,16 Therefore, unilateral nerve-sparing prostatectomy might not maintain sufficient neural volume for erectile function, and indeed showed worse sexual function than bilateral nerve sparing.17 Considering the limitation in nerve identification and the small nerve volume, it is preferable to preserve as many nerve fibers as possible in the form of a plate, not a bundle.

Trizonal neuronal distribution

From a practical perspective, the relevant neural tissue that we encounter during RALP can be grouped into three broad zones (Fig. 2): the PNP, the PNB and the ANP.18

image

Figure 2. Trizonal concept of the autonomic neural architecture around the prostate, PNP, PNB (arrowheads) and ANP.

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PNP:  The PNP is an integrating center for the processing and relay of neural signals. This plate is located lateral to the bladder neck, seminal vesicles and branches of the inferior vesical vessels (Fig. 3a). It is thick in the center near the seminal vesicles. The PNP extends posterolaterally to the base of the prostate and cavernous nerve candidates course in the most distal part. Distally, the plate continues as the classical neurovascular bundle while a few branches travel through the fascial and capsular tissue of the prostate as accessory pathways.

image

Figure 3. Proximal neurovascular plate and control of the vascular pedicle. (a) Cadaveric dissection showing the relationship between the SV and PNP (white arrows) according to the procedure for robotic prostatectomy. Bladder neck transaction is carried out, and the prostate is lifted with forceps. PNP consists of a vascular pedicle (black star) and neural component (white star). (b) Histological study with hematoxylin–eosin staining in the small square in (a). The vascular component and the neural component are intermingled. Black arrowheads, ganglion cells. (c,d) The surgical procedure. Viewing these structures laterally, we can estimate the approximate border between the neural (white star) and vessel components (black star), although these are actually intermingled. We have already cut a part of the vessels using a clip (asterisk). (d) Insertion of the tip of the left hand instrument into the border, ligation of the residual vessels using a clip and cutting sharply.

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PNB:  This corresponds to the classical bundle, but it carries neural impulses not only to the cavernous tissue, but also the urethral sphincter and to the end of the levator ani muscle. The PNB is enclosed within the layers of the LPF and is located at the posterolateral aspect of the prostate (Fig. 4a,b). It is thickest at the base, and has the most variable course and architecture near the apex. The fibers from HGN are more ventral, and from PSN are more dorsal, at the base of the prostate.

image

Figure 4. Release of the PNB. (a) Horizontal section of the posterolateral prostate. Ganglion cells (black arrows) in the PNB are along or attached to the posterolateral aspect of the prostate capsule (white arrows). Ganglion cells exist in the triangle of the prostate capsule, lateral pelvic fascia (white arrowheads) and Denonvillier's fascia (black arrowheads). Red, neural component. (b) Magnification of the small square in (a). Hematoxylin–eosin stain. (c) The surgical procedure.

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ANP:  There have been discussions about the putative accessory nerves, other than PNB, around the prostate.19,20 They are usually distributed within the layers of the LPF on the anterolateral and posterior aspect of the prostate, which might serve as additional conduits for neural impulses. Eichelberg et al. showed that one-fifth to one-quarter of nerves can be found along the ventral circumference of the prostate.21 Other accessory branches from both PNB occasionally form an apical plexus on the posterolateral aspect of the prostatic apex and urethra (Fig. 5a). This distal plexus was observed in 35% of cases, penetrating the RUM. This could potentially act as a neural pathway for not only cavernous tissue, but also the urethral sphincter. It could also serve as a safety mechanism to provide backup neural crosstalk between the two sides.

image

Figure 5. Apical neural plexus and apical transection. (a) A frontal section through the apex of the prostate. Many nerve fibers exist behind the apex of the prostate between the bilateral LA. Some of these penetrate the RUM encircled by dots. Hematoxylin–eosin staining. (b) The surgical procedure. Many nerve fibers can be seen behind the apex of the prostate during robotic prostatectomy. Bilateral PNB (black arrow) overlapped behind the apex, and formed the posterior plexus (white arrowhead).

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It is controversial how many nerves in ANP are responsible for erectile function. Costello et al. reported that parasympathetic fibers accounted for just 4–6.8% of the nerves located on the anterolateral aspect of the prostate using an immunohistochemical technique.22 However, that study had a significant limitation, because they examined just four cadavers.

Another issue of ANP is interindividual variation of examined specimens; for example, the background of the examined specimens. Hisasue et al. showed that the distribution of nNOS positive nerves around the prostate.23 The fibers were widely distributed, that is, their ratios are 2.7%, 6.4%, 13.1% 30.4%, 35.0% and 12.4% approximately 0 to 1, 1 to 2, 2 to 3, 3 to 4, 4 to 5 and 5 to 6 o'clock, respectively. However, according to baseline erectile function, the count of nNOS-positive fibers in the ED group was statistically greater than in the non-ED group.

Anatomical findings according to each procedure in state-of-the-art RALP

  1. Top of page
  2. Abstract
  3. Introduction
  4. Basic concept of neuroanatomy for radical prostatectomy
  5. Anatomical findings according to each procedure in state-of-the-art RALP
  6. Conclusion
  7. Conflict of interest
  8. References

We explain each step of RALP based on recent anatomical findings. First, we show the anatomical foundation, and then the surgical techniques based on the anatomy.

Endopelvic fascia, PPL and PPM for lateral and apical dissection of the prostate

Anatomical foundation

EPF is thought to refer to the fascia in the transitional area between the pelvic wall and pelvic viscera.24 However, the fascial anatomy near the prostate is not well accepted anatomically; that is, the existence and implications of the FLA are not considered. The FLA is folded back at the anterior or lateral aspect of the prostate behind the EPF. The overlap of the EPF and the foldback resemble a condensed white collar; that is, the fascial tendinous arch of the pelvis.25 The lowest part is connected to the PPL (Fig. 6).

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Figure 6. The typical anatomy around the endopelvic fascia. The overlap of the endopelvic fascia and the fascia of the levator ani muscle formed a condensed white collar; that is, the fascial tendinous arch of the pelvis (arrow). The lowest part connected to the pubo-prostatic ligament.

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The PPM is attached behind the insertion of the PPL, to form the inferomedial part of the levator ani muscle and is connected to the urethral sphincter (Fig. 7).26 That is to say, it forms a hammock around the urethra. The PPM, PPL and the fascial tendinous arch together to form a pubo-prostatic collar on the pelvic floor (Fig. 11a). These three structures surround and support the periurethral area, horizontally, sagittally and frontally, as a complex.

image

Figure 7. The RS, the urethra and the PPM in a fresh cadaver. The urethra was cut at the apex of the prostate and the forceps were inserted into the urethra retrogradely. The PPM (star) and PPL (white arrowhead) were separated from the pubic symphysis and drooped over the rectum. The RS shows an Ω shape, and the dorsal fibers coursed to the rectum and the apex of the prostate (black arrowhead and black arrow, respectively).

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image

Figure 11. (a) The preserved fascial tendious arch of the pelvis (arrow) and the PPL (closed star) form a plate of the pubo-prostatic collar. The white arrowhead shows the preserved nerve plate. (b) The completion of anterior restoration. The open star shows the position of the most proximal tie.

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Surgical technique

The EPF should be incised just medial to the fascial tendious arch, and the levator ani muscle should be removed laterally still covered by the FLA, without visualizing the muscle fibres. We stop the incision short of the PPL in order to avoid excessive separation around the apex.27 Because the antegrade approach is carried out in RALP, dissection of the dorsal vein complex and apex should be the final step.

Accessory pudendal artery for incision of EPF

Anatomical foundation

Before cutting the EPF, we sometimes must cut or separate the APA. However, the anatomy of APA and the significance of their preservation remain controversial. The occurrence rate of APA differs among studies; 70% in a cadaveric study,16 7% in a radiographic study,28 4% in RRP,29 and 25.7–30%30,31 in LRP. With a magnified view, Secin et al. showed that the visualization and accessibility advantages of laparoscopy might account for the higher intraoperative APA identification rate.31

Preservation of APA is thought to be significant for the maintenance of erectile function after radical prostatectomy. Droupy et al. reported during papaverine-induced erection that hemodynamic changes in APA and internal pudendal arteries are similar to those described in the cavernous arteries, thus showing the functional role of APA in penile erection.32 Rogers et al. compared patients with nerve-sparing radical prostatectomy with preservation of large APA to those without arterial preservation, and the effect of APA preservation increased the likelihood of potency more than twofold, and significantly shortened the time to regain potency.29

Beniot et al. also emphasized the contribution of APA not only to cavernous body irrigation, but also urethral irrigation.16 However, there have been no reports showing that the preservation of APA contributes to recovery from post-prostatectomy incontinence. We must concede that the functional role of APA remains unclear.

Retrotrigonal layer for the bladder neck and seminal vesicle transection

Anatomical foundation

The anatomical description of the area between the posterior bladder neck and seminal vesicle is unclear and not sufficient to carry out surgical procedures in this region. Surprisingly, a total of 20 citations published in contemporary peer-reviewed journals mistook the retrotrigonal layer for the anterior layer of DVF.33 We showed that the layer described above was clearly identified as a pinkish white midline strip with vertically oriented fibers that extended from the bladder trigone to the base of the prostate.34 Histologically, this layer was predominantly composed of smooth muscle.

The detrusor nerve to the urinary bladder is located on the medial aspect of the distal ureter, coursing caudally along the ureter to the ureterovesical junction.35 However, our anatomical research elucidated that the detrusor nerve in male adults is distributed more widely than in females.36 Therefore, bladder neck dissection might be the critical step that reduces the voiding function postoperatively.37

Surgical technique

First, we used the bimanual pinching technique to define the bladder-prostate junction.38 We gradually divided the posterior bladder neck with electrocautery adjacent to the midline until we reached the retrotrigonal layer described above. This marks the posterior limit of dissection in which we use electrocautery. Electrocautery dissection should not be used too laterally and proximally to avoid erectile and voiding dysfunction. The lateral pedicle, where it is very close to the distal end of the PNP, is preserved at this time. We started dissection of the seminal vesicles from the medial aspect without electrocautery or with minimal use, because these vessels are small here. Some seminal vesicle arteries can be seen in the lateral aspects. It is preferable to use small clips to cut the vessels without injuring the PNP.

Proximal neurovascular plate for control of the vascular pedicle

Anatomical foundation

Basically, the vascular pedicle and neural component to and along the prostate gradually part, resembling a Y-shaped structure.39 However, the neural component is actually intermingled with the vascular pedicle of the prostate, and there is no clear border between the two (Fig. 3b). Orientation, size and extent of the PNP vary significantly based on the prostate size, individual variations in anatomy and cancer-induced neovascularization.

Surgical technique

We should avoid using electrocautery or bulldog clamps during this phase of the operation.40 The first key step is to stay close to the prostate. The next step is to dissect the vessels in smaller packets using EndoWrist forceps, and control these vessels athermally using hemolock or metal clips (Fig. 3c,d).

DVF for posterior dissection

Anatomical foundation

There is no consensus on the usage of the term “Denonvilliers' fascia” during urological and colorectal surgeries.41 The first reason for the confusion is that we are not able to obtain a panoramic view of the rectogenital septum. The second reason is that clinical anatomy is quite different from histology. Consequently, surgeons might use the term “DVF” conceptually.

Histologically, there is a disorderly loose connective tissue between the cul-de-sac and RUM, and there is a tight and thick membrane that includes smooth muscle fibers between the cul-de-sac and posterior aspect of the prostate near the base of the seminal vesicle (Fig. 8).

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Figure 8. (a) Midsagittal section from the seminal vesicle to the urethra. There was a tight, thick membrane between the cul-de-sac and posterior aspect of the prostate near the base of the seminal vesicle (black arrowheads), and disorderly loose connective tissue was present between the cul-de-sac and the RUM (blue arrowheads). (b,c) Magnification of the squares in (a).

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Surgical technique

During RALP, we can directly and antegradely observe a magnified view behind the prostate. In all RALP cases, we can identify a membranous structure attached to the posterior aspect of the prostate near the base of the seminal vesicle or slightly distal to the base. After cutting this membrane, we encounter a mesh-like structure behind the posterior aspect of the prostate and easily find a flexible pathway to the apex, because there is a mesh-like structure that is not a two-layered structure42 (Fig. 9). To avoid rectal injury, and to preserve the neural components around the apex of the prostate, we must turn the tip of the Endowrist to the ventral side near the midline. Then, we should extend the space laterally without electrocautery. The relationship between the elevated prostate and nerve plate appears similar to “the train on the railroad”.

image

Figure 9. (a) The seminal vesicle has been elevated to easily identify the line, shown by white arrows, where the thick membrane from the cul-de-sac is attached. (b) After cutting this line, mesh-like connective tissue can be observed. (c) The mesh-like structure between the prostate and the rectum in a midsagittal section of a fresh cadaver.

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Fascial anatomy around the prostate for nerve release

Anatomical foundation

Many urologists have not reached a consensus about the fascial anatomy around the prostate, especially the terminology. We call the fascia covering the prostate LPF, which emerges after cutting the EPF and the thick fibrous tissue outside the prostate gland, the prostatic capsule, which is not a periprostatic structure, but the prostate itself. Some urologists reported there was another membrane between the LPF and prostatic capsule; that is, the periprostatic fascia described by Stolzenburg,43 or inner prostatic fascia described by Menon's group.44 However, as shown by Kiyoshima et al.,45 we should understand the fascial anatomy around the anterolateral aspect of the prostate as a multilayer LPF, the adipose tissue between these layers' fascia, and the prostatic capsule. Consequently, we call the dissection along the prostatic capsule “intrafascial”, and between the multilayer LPF “interfascial” dissection.

We showed the distribution of the lymphatic vessels in the LPF.46 Compared with the lymphatic vessels in the prostatic capsule, those in the LPF were fewer in the apex and the middle part of the prostate, but abundant in the base. The surgeon should pay more attention to carrying out dissection of the LPF, especially in patients with tumors considered to be at the base of the prostate.

The neural components within the LPF correspond to the anterior ANP in our trizonal concept. However, the functional classification of these nerves remains unclear as to which nerves are responsible for erectile function or urinary control. Consequently, we should preserve as many nerves as we can. To preserve the maximum number of nerves, we recommend a modification focusing on a high incision of the LPF; that is, the “Veil of Aphrodite” technique by Menon et al.20

Surgical technique

The prostate can be rotated to expose a potentially avascular triangle that is bound posteriorly by the DVF, laterally by the LPF and medially by the prostatic capsule. Once this triangle leaves the prostate, the dissection appears very elegant and can usually be carried out by gently pushing the prostate. We must avoid traction injury of the PNB by excessive pulling and blunt dissection (Fig. 4c). If patients have a small focus of less than Gleason 7 prostate cancer, we choose to preserve the anterior ANP using the Veil technique.

RS and RUM for apical transaction

Anatomical foundation

The apical neural plexus is formed on the posterolateral aspect of the prostatic apex and urethra from both the PNB. Some of these nerves penetrate the RUM. In addition, the distal part of the DVF terminates at the RS and RUM (Fig. 10).47 Of course, there are interindividual variations in the RS and RUM, and the shape of the RS is not always circular, but rather has an omega shape.48 The style of the termination of the DVF depends on the size and shape of the RUM and RS.

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Figure 10. Sagittal section 3 mm lateral from the middle. The distal part of the DVF terminated at the RS and RUM.

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In addition, the continence zone structure complicates the apical transection. There are interindividual variations in the relationship between the shape of the prostate and the RS. We must distinguish the two patterns of the apical structures, the apex overlapping RS and RS overlapping the apex.24

Surgical technique

Because we stop the incision short of the PPL in the first step, we should restart to separate the apex from the surrounding muscular structure and DVF. It is very important to dissect the neural component together with DVF and RUM (Fig. 5b). After complete apical separation from the PNB and posterior plexus, we thinly stitch the fascia covering the dorsal vein complex at the apex with a small needle. Viewing the apex from various aspects and imaging its shape, we cut the dorsal vein complex and anterior wall of the urethra. Then, the posterior wall of the urethra should be sharply cut to avoid PNB and posterior plexus injury. Finally, using the needle stitched at the fascia, the dorsal vein complex is closed by running sutures carefully without injury or deformity of the RS.

Periurethral structure for posterior and anterior restoration

Posterior restoration

Anatomical foundation:  Recently, an Italian group showed a milestone procedure for improving the early recovery of urinary continence after RRP49 and LRP.50 They carried out posterior stitches between the distal and proximal cut edge of the DVF before vesicourethral anastomosis. One of the reasons for early incontinence after radical prostatectomy is because of the shortening of the sphincter's anatomical and functional length after caudal retraction of the sphincteric complex and disruption of the DVF.51 The aim of this procedure is to restore the structure of the posterior continence zone.

Surgical technique:  As aforementioned, there are many neural components along and penetrating the RUM running to the cavernous tissue or sphincter. Stitches that are very deep or very close to the urethral stump might severely affect erectile function and urinary continence.

Anterior restoration

Surgical technique:  For early recovery of urinary continence, we showed the usefulness of anterior stitches between the pubo-prostatic collar and bladder neck27,52 (Fig. 11b). This collar consists of three parts: the PPL, the fascial tendinous arch and the PPM. Although this is also a suspension technique, it is quite different from the previous method, because the anterior support in this procedure is not only PPL, but also the puboprostatic collar as a complex.

Nerve graft and nerve reconstruction

Anatomical foundation

Nerve graft interposition using the sural nerve after non-nerve sparing radical prostatectomy has been offered by Scardino's group.53 In this initial report, successful vaginal penetration was possible in 33% without sildenafil and 50% with sildenafil. Although some institutions have tried to confirm the usefulness, we have not achieved a consensus on this issue. Recently, Scardino's group revised the results downward; the clinically meaningful erection recovery rate was 11% at 5 years with or without medication.54 Based on recent anatomical findings, this result might be only natural. Because the cavernous nerve fibers do not form a bundle, suturing with a precise graft interposition graft is very difficult. In view of the adverse effects of prolonged surgery, incisional discomfort and sensory deficit on the side of the foot, the usefulness of this technique could be restrictive.

To replace an autologous nerve graft, the development of artificial material is ongoing. Matsuura et al. reported a simple technique in which a piece of alginate gel sheet was placed over the gap of the cavernous nerves without suturing in a rat model.55 If artificial material is available, we can cover any shape of deficit in a bundle-like or sheet-like manner.

Surgical technique

We carry out the new technique for nerve reconstruction during RALP56 (Fig. 12). After nerve resection, we place several direct sutures between both stumps of neurovascular tissue. It might be difficult during RRP and LRP, and might only be possible using robotic instruments and techniques. The procedure is very promising with regard to recovery of sexual function.

image

Figure 12. Direct sutures between both stumps of the neurovascular tissue promote recovery of sexual function.

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Conclusion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Basic concept of neuroanatomy for radical prostatectomy
  5. Anatomical findings according to each procedure in state-of-the-art RALP
  6. Conclusion
  7. Conflict of interest
  8. References

We showed new anatomical findings around the prostate for radical prostatectomy, especially that using RALP. Some observations refute the conventional consensus; for example, the cavernous nerve is always within the neurovascular bundle. Surgical anatomy should always be developing and changing with advances in surgical approaches.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Basic concept of neuroanatomy for radical prostatectomy
  5. Anatomical findings according to each procedure in state-of-the-art RALP
  6. Conclusion
  7. Conflict of interest
  8. References
  • 1
    Menon M, Tewari A, Peabody JO et al. Vattikuti Institute prostatectomy, a technique of robotic radical prostatectomy for management of localized carcinoma of the prostate: experience of over 1100 cases. Urol. Clin. North Am. 2004; 31: 70117.
  • 2
    Ficarra V, Cavalleri S, Novara G, Aragona M, Artibani W. Evidence from robotic-assisted laparoscopic radical prostatectomy: a systematic review. Eur. Urol. 2007; 51: 4556.
  • 3
    Srivastava A, Grover S, Sooriakumaran P, Tan G, Takenaka A, Tewari AK. Neuroanatomic basis for traction-free preservation of the neural hammock during athermal robotic radical prostatectomy. Curr. Opin. Urol. 2011; 21: 4959.
  • 4
    Walsh PC, Donker PJ. Inpotence following radical prostatectomy: insight into etiology and prevention. J. Urol. 1982; 128: 4927.
  • 5
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