ANATOMICAL ANALYSIS OF THE NEUROVASCULAR BUNDLE SUPPLYING PENILE CAVERNOUS TISSUE TO ENSURE A RELIABLE NERVE GRAFT AFTER RADICAL PROSTATECTOMY

Correlation between FA and ADC, number and length of the periprostatic neurovascular fibers

PURPOSE

Our aim was to explore the relation between FA and ADC, number and length of the periprostatic neurovascular fibers (PNF) by means of 1.5 T Diffusion Tensor Imaging (DTI) imaging through a multivariate linear regression analysis model.

METHODS

For this retrospective study, 56 patients (mean age 63.5 years), who underwent 1.5-T prostate MRI, including DTI, were enrolled between October 2014 and December 2018. Multivariate regression analysis was performed to evaluate the statistically significant correlation between FA values (dependent variable) and ADC, the number and the length of PNF (independent variables), if p-value <0.05. A value of 0.5 indicated poor agreement; 0.5-0.75, moderate agreement; 0.75-0.9, good agreement; 0.61-0.80, good agreement; and 0.9-1.00, excellent agreement.

RESULTS

The overall fit of the multivariate regression model was excellent, with R² value of 0.9445 (R² adjusted 0.9412; p < 0.0001). Multivariate linear regression analysis showed a statistically significant correlation (p < 0.05) for all the three independent variables. The r partial value was -0.9612 for ADC values (p < 0.0001), suggesting a strong negative correlation, 0.4317 for the number of fiber tracts (p < 0.001), suggesting a moderate positive correlation, and -0.306 for the length of the fiber tracts (p < 0.05), suggesting a weak negative correlation.

CONCLUSIONS

Our multivariate linear regression model has demonstrated a statistically significant correlation between FA values of PNF with other DTI parameters, in particular with ADC.

Positional relationship between the lateral border of Denonvilliers' fascia and pelvic plexus

Denonvilliers' fascia is an important landmark of the dissection layer during prostate or rectal surgeries. However, there are few reports on its lateral extension. This anatomical study aimed to define the lateral border of Denonvilliers' fascia and use it as an anatomical landmark to identify the origin and distribution of the nerve branches of the pelvic plexus. We investigated the lateral extent and position of the lateral border of Denonvilliers' fascia through macroscopic examination of 12 pelvic halves from eight cadavers and histological examination of two cadavers. The Denonvilliers' fascia extended laterally to be attached to the pelvic plexus on the lateral border. The origins of nerve branches from the pelvic plexus to the pelvic organs, except the rectum, were located anterior or anterosuperior to the lateral border of Denonvilliers' fascia. The origins of nerve branches to the prostate were mainly anterior to the lateral border of Denonvilliers' fascia; however, in 3/12 pelvic halves, the nerve branches originated in the region posteroinferior to the lateral border of Denonvilliers' fascia. The attachment point of Denonvilliers' fascia to the prostate was more superior in these three pelvic halves (distance from the top point of the posterior surface of the prostate to the attachment point, 5.6 ± 1.9 mm) than that in the other nine pelvic halves (10.1 ± 3.6 mm). The lateral border of Denonvilliers' fascia is closely related to the pelvic plexus, suggesting its usefulness as an anatomical landmark to identify the origin of nerve branches from the pelvic plexus.

Depiction of periprostatic nerve fibers by means of 1.5 T diffusion tensor imaging

PURPOSE

The knowledge of periprostatic nerve fiber (pNF) is still incomplete by means of conventional MRI. The purpose of our study was to demonstrate if DTI imaging is able to depict anatomical features of pNF.

METHODS

For this retrospective study, fifty-six patients (mean age 63.5 years), who underwent 1.5-T prostate MRI, including 32 directions DTI, were enrolled between October 2014 and December 2018. ANOVA test and Student's t-test were performed between the mean values of the number, FA values, and fiber length of pNF between base and mid-gland, mid-gland and apex, base and apex, right and left side, and anterior and posterior face of the prostate. A qualitative analysis was performed to detect the main orientation of pNF through a colorimetric 3D tractographic reconstruction.

RESULTS

The number of pNF showed a decrease from the base (322) to mid-gland (248) and apex (75) (p < 0.05). The FA values were higher at base and mid-gland (0.435 and 0.456) compared to the apex (0.313) (p < 0.05). The length of pNF was higher at apex (13.4 mm) compared to base (11.5 mm) and mid-gland (11.7 mm) (p < 0.05). The number of pNF was higher on the posterior face compared to the anterior face at base (186 vs 137), (p < 0.001). The FA values were higher on the posterior face compared to the anterior face at base (0.452 vs 0.417), mid-gland (0.483 vs 0.429), and apex (0.42 vs 0.382), (p < 0.05). The length of the pNF was higher in the posterior (14.7 mm) than in the anterior face (12 mm) at apex (p < 0.001). The main orientation of pNF was longitudinal in all patients (56/56, 100%).

CONCLUSIONS

DTI imaging has been demonstrated able to depict anatomical features of pNF.

Comprehensive approach for preserving cavernous nerves and erectile function after radical prostatectomy in the era of robotic surgery

A nerve-sparing procedure during robot-assisted radical prostatectomy has been considered one of the most important techniques for preserving postoperative genitourinary function. The reason is that adequate nerve-sparing procedures could preserve both erectile function and lower urinary tract function after surgery. When a nerve-sparing procedure is carried out, the cavernous nerves themselves cannot be visualized, despite the magnified viewing field during robot-assisted radical prostatectomy. Thus, nerve-sparing procedures have been considered challenging operations, even now. However, because not all surgeons have carried out a sufficient number of nerve-sparing procedures, the development of new nerve-sparing procedures or new methods for mapping the cavernous nerves is required. Recently, various new operative techniques, for example, Retzius-sparing robot-assisted radical prostatectomy, transvesical robot-assisted radical prostatectomy and retrograde release of neurovascular bundle technique during robot-assisted radical prostatectomy, have been developed. In addition, new surgical devices, for example, biological/bioengineering solutions for cavernous nerve protection and devices for identifying the cavernous nerves during radical prostatectomy, have developed to preserve the cavernous nerves. In contrast, limitations or problems in preserving cavernous nerves and postoperative erectile function have become apparent. In particular, the recovery rate of erectile function, the positive surgical margin rate at the site of nerve-sparing and the indications for nerve sparing have become obvious with the accumulation of much evidence. Furthermore, predictive factors for postoperative erectile function after nerve-sparing procedures have also been clarified. In this article, the importance of a comprehensive approach for early recovery of erectile function in the robot-assisted radical prostatectomy era is discussed.

The distribution pattern of periprostatic neurovascular bundles examined with successive celloidin slices

Background

Although several distribution patterns of periprostatic neurovascular bundles have been proposed, variant dissection technique based on these patterns still confused surgeons. The aim of this study was to describe the periprostatic neurovascular bundles and their relationship with the fascicles around prostate and provide the accurate morphologic knowledge of periprostatic tissue for prostate operation.

Methods

The pelvic viscera were obtained from 26 adult male cadavers. They were embedded in celloidin and cut into successive slices. The slices were explored with anatomic microscopy. 3-Dimensional reconstruction was achieved with celloidin sections and series software.

Results

The prostatic capsule which surrounded the dorsal, bilateral aspect of the prostate was attached ventrally to anterior fibrous muscular stroma (AFMS). The lower part of the striated sphincter completely embraced the urethral; the upper part of this muscle covered the lower ventral surface of prostate. The upper ventral surface of prostate is covered by the circular muscle of detrusor. The levator fascia and the capsule adhered on the most convex region of the lateral prostate, but separated on the other region. The pelvic neurovascular bundles (PNVB) divided into the anterior and posterior divisions. The anterior division continued as dorsal vascular complex (DVC). The distal part of DVC entered into penile hilum. The posterior division continued as neurovascular bundles, and then as the cavernous supply (CS). The distal part of CS joined into pudendal neurovascular bundles.

Conclusions

The capsule and AFMS formed a pocket like complex. There were anterior and posterior neurovascular approaches from PNVB to penile hilum.

A new method in robotic-assisted laparoscopic radical prostatectomy: personalised neuroprotective surgery with neuromonitoring system-randomised controlled study

PURPOSE

Erectile dysfunction is one of the important morbidities following the radical prostatectomy (RP) surgeries. The goal of this research is to investigate the contribution of intraoperative neuromonitorisation method (IONM) on postoperative erectile function in patients who underwent robotic-assisted laparoscopic radical prostatectomy (RALP) with the localise prostate cancer (LPCa).

MATERIALS AND METHODS

In this randomised controlled study contains 88 patients with LPCa were classified based on D'Amico Risk Classification. 61 patients who met the necessary criteria were divided into two groups as neuromonitorisation group (n = 30) and control group (n = 31). All patients were operated under general anaesthesia. All patients included in the study underwent RALP by robotic-assisted system. For the neuromonitorisation, IONM electromyography electrodes were placed to the right and left cavernous bodies in neuromonitorisation group. Impulses in the corpora cavernosa were considered significant. Postoperative erectile functions were determined according to the 3th and 6th month IIEF-5 scores. Demographic data, operative procedures, Gleason scores, final pathology, surgery border, PSA, and IIEF-5 score of patients were recorded.

RESULTS

No statistically difference was found between the groups in terms of demographic data, operative procedures, Gleason scores, final pathology, surgery border, and third-month PSA levels (p > 0.05). There was statistically difference between the postoperative third and 6-month IIEF-5 score in neuromonitorisation group (p < 0.05).

CONCLUSION

In the IONM technique, high rate of improvement in erectile function was observed in the early period thanks to personalised neuroprotective surgery applied to patients.

Imaging modalities aiding nerve-sparing during radical prostatectomy

Nerve-sparing robot-assisted radical prostatectomy has decreased the post-surgical complications of prostate surgery, but has not eliminated it. The ability to view the microstructure will enable better surgical decisions and lead to better post-surgical outcomes. An ideal imaging modality should provide rapid image acquisition, be low cost, and be specific to the tissue being examined. This article aims to review the current literature to compare three main techniques: multiphoton microscopy (MPM), optical coherence tomography, and confocal microscopy, to see which of these techniques may be best applied in surgical procedures in the future. Embase and Medline were used as the primary databases. Combinations of various key words were used while researching the literature. These included: "Radical prostatectomy," "nerve-sparing," "nerve mapping," "multiphoton microscopy," "Confocal microscopy," and "Optical Coherence Tomography." Thereafter, the relevant results were selected and used in the review. Although optical coherence tomography is a low cost and compact modality, it lacks cellular resolution, while confocal microscopy offers great cellular resolution but lacks depth. MPM, on the other hand, provides sufficient depth and produces high-resolution images. The limitation of MPM is its lack of portability, however the advent of dual-modality MPM may be a way forward.

Analysis of Spatial Dose-Volume Relationships and Decline in Sexual Function Following Permanent Brachytherapy for Prostate Cancer

OBJECTIVE

To explore relationships between dose to periprostatic anatomic structures and erectile dysfunction (ED) outcomes in an institutional cohort treated with prostate brachytherapy.

METHODS

The Sexual Health Inventory for Men (SHIM) instrument was administered for stage cT1-T2 prostate cancer patients treated with Pd-103 brachytherapy over a 10-year interval. Dose volume histograms for regional organs at risk and periprostatic regions were calculated with and without expansions to account for contouring uncertainty. Regression tree analysis clustered patients into ED risk groups.

RESULTS

We identified 115 men treated with definitive prostate brachytherapy who had 2 years of complete follow-up. On univariate analysis, the subapical region (SAR) caudal to prostate was the only defined region with dose volume histograms parameters significant for potency outcomes. Regression tree analysis separated patients into low ED risk (mean 2-year SHIM 20.03), medium ED risk (15.02), and high ED risk (5.54) groups. Among patients with good baseline function (SHIM ≥ 17), a dose ≥72.75 Gy to 20% of the SAR with 1 cm expansion was most predictive for 2-year potency outcome. On multivariate analysis, regression tree risk group remained significant for predicting potency outcomes even after adjustment for baseline SHIM and age.

CONCLUSION

Dose to the SAR immediately caudal to prostate was predictive for potency outcomes in patients with good baseline function. Minimization of dose to this region may improve potency outcomes following prostate brachytherapy.

An updated approach to incremental nerve sparing for robot-assisted radical prostatectomy

OBJECTIVES

To update the algorithm for performing incremental nerve sparing (NS) using our multiparametric magnetic resonance imaging (mpMRI)-based nomogram.

PATIENTS AND METHODS

We applied the coefficients of the nomogram to the observations extracted from our population of patients who underwent robot-assisted radical prostatectomy between February 2014 and October 2015 and who received preoperative mpMRI. The information considered were PSA level, highest side-specific biopsy Gleason grade group, highest ipsilateral percentage core involvement with the highest Gleason grade group, and extracapsular extension (ECE) on mpMRI. The nomogram-derived probability [P (%)], after internal validation, was used as the independent variable on a classification tree to identify the most significant thresholds for ECE prediction. Incremental NS was performed as follows: Grade 1 NS: intrafascial dissection between the peri-prostatic veins and the pseudocapsule of the prostate; Grade 2 NS: inter-fascial dissection along the peri-venous plane; Grade 3 NS: inter-fascial dissection through the outer compartment of the lateral prostatic fascia; Grade 4 NS: extrafascial dissection.

RESULTS

Data from 561 patients were considered, and 829 prostatic lobes with biopsy-documented tumour were analysed. Overall, 142 lobes presented ECE that was focal in 27 (19%) cases. The classification tree identified four risk categories. In the low- [P (%) ≤10], intermediate- [P (%) 10-21], high [P (%) 21-73] and very-high-risk [P(%) >73] groups, the ECE rates were 3.3%, 16%, 61.6% and 90%, respectively. Amongst those, ECE was focal in 41.7%, 31.7%, 7.9% and 0%, respectively.

CONCLUSION

We suggest that Grade 1 NS (intrafascial) should be performed in the low-risk group. The inter-fascial approach, namely grades 2 and 3 NS, should be performed in the intermediate- and high-risk categories, respectively. Grade 4 NS (extrafascial) should be performed in the very-high-risk group. The current algorithm yields a better accuracy than the previous one; however, prospective validation is warranted.

Neuro-anatomic basis of potency recovery after radical prostatectomy: an expert's point of view

INTRODUCTION

From 25% to 95% of those who have undergone radical prostatectomy (RP) report erectile dysfunction 12 months after surgery. We attempt a review of the available evidence regarding the anatomy of the cavernous nerves and the surgical refinements to enhance sexual function recovery after surgery.

EVIDENCE ACQUISITION

The PubMed/Medline database was searched. Duplicates were removed. Studies were selected by the authors according to the aim of the present review.

EVIDENCE SYNTHESIS

The cavernous nerves are deemed responsible for erections, but their exact function is still a matter of debate. They do not necessarily have the same distribution in all individuals: in most the cases, these nerves are located posterolaterally, however, it is not uncommon to find some fibers on the anterolateral aspects of the prostate, especially towards the apex. Several technical strategies were proposed in order to intraoperatively identify and spare the neurovascular bundles: despite all efforts, clinical results are still only partially satisfying.

CONCLUSIONS

The recovery of potency is one of the most unpredictable outcomes after RP. The advent of the robotic surgical system seems to have brought a trend towards a faster recovery of erectile function.

Intrafascial nerve-sparing radical prostatectomy improves patients' postoperative continence recovery and erectile function: A pooled analysis based on available literatures

BACKGROUND

Intrafascial nerve-sparing prostatectomy has been currently applied based on the updated anatomic understanding of periprostatic cavernous nerves, in order to provide patients better postoperative recovery of continence and potency. The aim of our study is to perform a pooled analysis of available literatures regarding the functional outcomes following intrafascial nerve-sparing technique.

METHODS

The authors performed database searches of articles published till October 2017 on PubMed using following keywords across the "title" and "abstract" field of the records: intrafascial, veil, curtain dissection, high anterior release, incremental nerve sparing, and radical prostatectomy. Fulfilled papers were screened and data were extracted independently by 3 reviewers. Main outcome was the postoperative continence and potency rate stratified by follow-up durations. Both 1-arm and comparative meta-analyses were performed and meta-regression models were conducted to evaluate the confounding factors.

RESULTS

Using the electronic search strategy, a total of 71 records were retrieved and 20 studies were finally included, of which 6 were surgical series and 14 were controlled studies. Our 1-arm meta-analysis summarized the pooled continence rates after intrafascial prostatectomy were 59.4%, 76.2%, 89.9%, and 92.2% at postoperative follow-up of 1, 3, 6, and 12 months, respectively. Regardless of the variance in potency definition, the pooled potency rates after intrafascial prostatectomy were 42.2%, 54.2%, and 72.2% at 3, 6, and 12 months, respectively. Comparative analysis showed that the intrafascial group offered better continence rates at 1, 3, and 6 months with an odds ratio (OR) of 2.38 (95% confidence interval [CI]: 1.73-3.26), 1.82 (95% CI: 1.18-2.82), and 2.19 (95% CI: 1.43-3.34) as compared with the interfascial group. Moreover, potency rate in the intrafascial group was higher at 12 months than in the interfascial group, with an OR of 2.44 (95% CI: 1.35-4.42).

CONCLUSION

Based on the limited evidence, our study demonstrated that intrafascial nerve-sparing prostatectomy could provide patients with earlier recovery of continence and better erectile function compared with conventional interfascial approach, but physiological mechanisms about this technique still need further study.

Reappraisal of the lateral rectal ligament: an anatomical study of total mesorectal excision with autonomic nerve preservation

PURPOSE

The term "lateral rectal ligament" in surgery for rectal cancer has caused confusion regarding its true existence and contents. In previous studies, investigators claimed the existence of the ligament and described its topographical features as neurovascular structures and their surrounding connective tissues located at the anterolateral aspect of the distal rectum or the posterolateral aspect of the middle rectum. The purpose of this study is to evaluate the structure of the so-called "lateral rectal ligament" in cadaver dissections.

METHODS

Dissection was performed in nine cadavers (eight males and one female, aged 73 to 94 years) in accordance with typical total mesorectal excision techniques. During dissection, structures related to "the ligament" were examined and images recorded.

RESULTS

At the anterolateral aspect of the distal rectum, the middle rectal artery was noted to be crossing the fusion of Denonvilliers' fascia and the proper rectal fascia. At the posterolateral aspect of the middle rectum, there was a structure which consisted of the rectal nerves running through the fusion of the pelvic fasciae. Although called "ligaments," neither structure contained discrete strong connective tissue fixing the rectum to the pelvic wall.

CONCLUSIONS

The proper rectal fascia and surrounding pelvic fasciae fuse firmly anterolaterally and posterolaterally where neurovascular structures course toward the rectum. During a total mesorectal excision, the surgical dissection plane coincides with the fused part of the fasciae, which had long been considered the "lateral rectal ligament."

Site-dependent differences in the composite fibers of male pelvic plexus branches: an immunohistochemical analysis of donated elderly cadavers

Background

Although the pelvic autonomic plexus branches are considered to be a mixture of sympathetic and parasympathetic nerves, little is known regarding the composite fibers of the pelvic plexus branches. This study aimed to investigate the immunohistochemical features of sympathetic and parasympathetic nerves in the pelvic autonomic plexus branches.

Methods

Using 10 donated elderly male cadavers, the detailed topohistology of nerve fibers at and around the bladder, seminal vesicle, prostate, and rectum was examined. Neuronal nitric oxide synthase (nNOS) and vasoactive intestinal polypeptide (VIP) were used as parasympathetic nerve markers; tyrosine hydroxylase (TH) was used as a sympathetic nerve marker. The myenteric plexus of the colon was utilized as a positive control.

Results

Most nerve fibers in the bladder, seminal vesicle, prostate, and rectum were both nNOS- and TH-positive. Thus, pelvic plexus branches were classified into two types: 1) triple-positive mixed nerves (nNOS+, VIP+, TH+, thick myelinated fibers + or -) and 2) double-positive mixed nerves (nNOS+, VIP-, TH+, thick myelinated fibers + or -). Notably, triple-positive nerves were localized within the posterosuperior part of the plexus (near the rectum) and travelled anteroinferiorly toward the posterolateral corner of the prostate. The posteriorly and inferiorly located nerves were predominantly composed of parasympathetic, rather than sympathetic, fibers. In contrast, nerve fibers within and along the bladder and seminal vesicle contained either no or few VIP-positive nerves. These superiorly located nerves were characterized by clear sympathetic nerve dominance.

Conclusions

The nerves of the pelvic plexus branches were clearly classified into nerves around the bladder and seminal vesicle (VIP-negative) and nerves around the prostate (VIP-positive). Although nNOS- and VIP-positive nerve fibers are candidate cavernous nerves, cavernous nerve identity cannot be definitively concluded for these nerves in the periprostatic region.

Periprostatic innervation: New issues based on segmental analysis of 10 human cadaver pelvic blocs

BACKGROUND

The exact paths of periprostatic nerves have been under debate over the last decades. In the present study, the topographic distribution of nerves around the prostate and their relative distances from the prostatic capsule were analyzed in male cadaver visceral blocs.

METHODS

The pelvic organs from ten fresh male cadavers were removed and serial sectioned en bloc for histological investigation. The macroslices was divided into four sectors. Each sector was centrally covered with a raster dividing each sector in three subsectors numbered clockwise. The prostatic capsule was identified, and distances of 2.5 and 5 mm from the prostate were demarked with lines. We quantified the number of nerve fibers present in each subsector of each slide and recorded their position relative to the prostatic capsule.

RESULTS

In general, the topographic analysis revealed that the majority of nerves were identified in sectors 4 through 9, corresponding to the posterolateral and posterior surfaces of the prostate gland. At the prostate base, the majority of nerves were found at the posterolateral and posterior surfaces of the gland. Within the mid-region of the prostate, the same topographic distribution pattern was observed, but the nerve fibers were closer to the prostatic capsule. At the apical region, the percentage of nerve fibers identified in the anterior region was higher, despite their major concetration in the posterior surface. The nerves identified at the apex were mainly located up to 2.5 mm from the prostate. This proximity to the prostate was specifically observed in the anterolateral and anterior sectors. In the craniocaudal sense, the percentage of nerves identified between 2.5 and 5 mm from the prostatic capsule remained constant.

CONCLUSIONS

A significant number of nerve fibers were present in the anterior and anterolateral positions, especially at the apex. The anterior nerves were closer to the prostate. This proximity suggests that the anterior nerves may participate in local physiology and that the cavernous nerves are probably formed by the posterior nerve fibers. It is likely that the safe distance of 2.5 mm from all surfaces of the prostate may be related to cavernous fiber preservation.

Visualization of prostatic nerves by polarization-sensitive optical coherence tomography

Preservation of prostatic nerves is critical to recovery of a man's sexual potency after radical prostatectomy. A real-time imaging method of prostatic nerves will be helpful for nerve-sparing radical prostatectomy (NSRP). Polarization-sensitive optical coherence tomography (PS-OCT), which provides both structural and birefringent information of tissue, was applied for detection of prostatic nerves in both rat and human prostate specimens, ex vivo. PS-OCT imaging of rat prostate specimens visualized highly scattering and birefringent fibrous structures superficially, and these birefringent structures were confirmed to be nerves by histology or multiphoton microscopy (MPM). PS-OCT could easily distinguish these birefringent structures from surrounding other tissue compartments such as prostatic glands and fats. PS-OCT imaging of human prostatectomy specimens visualized two different birefringent structures, appearing fibrous and sheet-like. The fibrous ones were confirmed to be nerves by histology, and the sheet-like ones were considered to be fascias surrounding the human prostate. PS-OCT imaging of human prostatectomy specimens along the perimeter showed spatial variation in the amount of birefringent fibrous structures which was consistent with anatomy. These results demonstrate the feasibility of PS-OCT for detection of prostatic nerves, and this study will provide a basis for intraoperative use of PS-OCT.

Role of Schwann cells in the regeneration of penile and peripheral nerves

Schwann cells (SCs) are the principal glia of the peripheral nervous system. The end point of SC development is the formation of myelinating and nonmyelinating cells which ensheath large and small diameter axons, respectively. They play an important role in axon regeneration after injury, including cavernous nerve injury that leads to erectile dysfunction (ED). Despite improvement in radical prostatectomy surgical techniques, many patients still suffer from ED postoperatively as surgical trauma causes traction injuries and local inflammatory changes in the neuronal microenvironment of the autonomic fibers innervating the penis resulting in pathophysiological alterations in the end organ. The aim of this review is to summarize contemporary evidence regarding: (1) the origin and development of SCs in the peripheral and penile nerve system; (2) Wallerian degeneration and SC plastic change following peripheral and penile nerve injury; (3) how SCs promote peripheral and penile nerve regeneration by secreting neurotrophic factors; (4) and strategies targeting SCs to accelerate peripheral nerve regeneration. We searched PubMed for articles related to these topics in both animal models and human research and found numerous studies suggesting that SCs could be a novel target for treatment of nerve injury-induced ED.

A Critical Analysis of the Current Knowledge of Surgical Anatomy of the Prostate Related to Optimisation of Cancer Control and Preservation of Continence and Erection in Candidates for Radical Prostatectomy: An Update

CONTEXT

In 2010, we published a review summarising the available literature on surgical anatomy of the prostate and adjacent structures involved in cancer control and the functional outcome of prostatectomy.

OBJECTIVE

To provide an update based on new literature to help the surgeon improve oncologic and surgical outcomes of radical prostatectomy (RP).

EVIDENCE ACQUISITION

We searched the PubMed database using the keywords radical prostatectomy, anatomy, neurovascular bundle, nerve, fascia, pelvis, sphincter, urethra, urinary continence, and erectile function. Relevant articles and textbook chapters published since the last review were critically reviewed, analysed, and summarised. Moreover, we integrated aspects that were not addressed in the last review into this update.

EVIDENCE SYNTHESIS

We found new evidence for several topics. Up to 40% of the cross-sectional surface area of the urethral sphincter tissue is laterally overlapped by the dorsal vascular complex and might be injured during en bloc ligation. Denonvilliers fascia is fused with the base of the prostate in a horizontal fashion dorsally/caudally of the seminal vesicles, requiring sharp detachment when preserved. During extended pelvic lymph node dissection, the erectile nerves are at risk in the presacral and internal iliac area. Dissection planes for nerve sparing can be graded according to the amount of tissue left on the prostate as a safety margin against positive surgical margins. Vascular structures can serve as landmarks. The urethral sphincter and its length after RP are influenced by the shape of the apex. Taking this shape into account allows preservation of additional sphincter length with improved postoperative continence.

CONCLUSIONS

This update provides additional, detailed information about the surgical anatomy of the prostate and adjacent tissues involved in RP. This anatomy remains complex and widely variable. These details facilitate surgical orientation and dissection during RP and ideally should translate into improved outcomes.

PATIENT SUMMARY

Based on recent anatomic findings regarding the prostate and its surrounding tissue, the urologist can individualise the dissection during RP according to cancer and patient characteristics to improve oncologic and functional results at the same time.

Evaluating the Impact of PSA as a Selection Criteria for Nerve Sparing Radical Prostatectomy in a Screened Cohort

Purpose. We investigated whether NS-RP increased risk of PSA failure and whether PSA should be included as a selection criterion for NS. Methods. We evaluated 357 consecutive men with screen-detected PC who underwent open RP without adjuvant radiotherapy between 9/11/2001 and 12/30/2008. Criteria for NS included Gleason score ≤3 + 4, percentage of positive biopsies (PPB) ≤50%, percentage of core involvement ≤50%, nonapical location, no perineural invasion, and no palpable disease on pre- or intraoperative exam but did not include a PSA threshold. Cox multivariable regression assessed whether increasing PSA or unilateral- or bilateral-NS versus non-NS-RP was associated with PSA failure adjusting for prognostic factors. Results. After a median follow-up of 3.96 years, 34 men sustained PSA failure (9.5%). Increasing PSA was significantly associated with increased risk of PSA failure in the interaction model (adjusted hazard ratio (AHR): 1.09 [95% CI: 1.03-1.16]; P = 0.005), whereas unilateral (AHR: 1.24 [95% CI: 0.36-4.34]; P = 0.73) or bilateral NS (AHR: 0.41 [95% CI: 0.06-2.59]; P = 0.34) versus non-NS RP was not. Conclusion. NS-RP in a screened cohort did not increase risk of PSA failure using NS criteria not including PSA.

Visualization of periprostatic nerve fibers before and after radical prostatectomy using diffusion tensor magnetic resonance imaging with tractography

PURPOSE

The purpose was to evaluate whether the diffusion tensor imaging (DTI) technique can visualize changes in the numbers of periprostatic nerve fibers before and after nerve-sparing and non-nerve-sparing prostatectomy.

METHOD

Fifty-two prostate cancer patients underwent 3-T magnetic resonance imaging including DTI before and after prostatectomy.

RESULTS

After non-nerve-sparing prostatectomy, the numbers of tracts were significantly decreased at base (218.8±198.8 vs. 60.5±88.7), midgland (124.1±134.5 vs. 32.5±45.7), and apex (103.1±127.4 vs. 29.1±57.1). However, after nerve-sparing prostatectomy, the numbers of tracts were not changed significantly at base (170.5±139.7 vs. 127.7±146.0), midgland (134.3±140.8 vs. 83.7±58.3), and apex (64.1±68.4 vs. 62.3±61.9).

CONCLUSION

DTI technique may be feasible for visualization of periprostatic nerve fibers.

A comprehensive review of neuroanatomy of the prostate

Although oncologic efficacy is the primary goal of radical prostatectomy, preserving potency and continence is also important, given the indolent clinical course of most prostate cancers. In order to preserve and recover postoperative potency and continence after radical prostatectomy, a detailed understanding of the pelvic anatomy is necessary to recognize the optimal nerve-sparing plane and to minimize injury to the neurovascular bundles. Therefore, we reviewed the most recent findings from neuroanatomic studies of the prostate and adjacent tissues, some of which are contrary to the established consensus on pelvic anatomy. We also described the functional outcomes of radical prostatectomies following improved anatomical understanding and development of surgical techniques for preserving the neurovascular bundles.

Subsurface near-infrared laser stimulation of the periprostatic cavernous nerves

Successful identification and preservation of the cavernous nerves (CN), which are responsible for sexual function and vulnerable to damage during prostate cancer surgery, will require subsurface detection of the CN's beneath a thin fascia layer. This study explores the feasibility of optical nerve stimulation (ONS) in the rat with a fascia layer placed over the CN. Two near-infrared diode lasers with wavelengths of 1455 and 1550 nm were operated in continuous-wave mode for stimulation of the CN in 8 rats, in vivo. Successful ONS was confirmed by an intracavernous pressure (ICP) response in the rat penis at 1455 nm through fascia with a thickness up to 110 μm and at 1550 nm through fascia with a thickness up to 450 μm. Higher incident laser power was required to produce an ICP response as fascia thickness was increased. Also, weaker and slower ICP responses were observed as fascia thickness was increased. Subsurface ONS of the rat CN at a depth of 450 μm using a 1550 nm laser is feasible as an intermediate step towards developing ONS as an intra-operative diagnostic tool for identification and preservation of the cavernous nerves during prostate cancer surgery.

Diffusion tensor magnetic resonance tractography of the prostate: feasibility for mapping periprostatic fibers

OBJECTIVE

To evaluate the feasibility of diffusion tensor imaging (DTI) tractography of the prostate for mapping of periprostatic neurovascular anatomy.

METHODS

Eight men with prostate cancer scheduled to undergo nerve-sparing robot-assisted radical prostatectomy (RARP) underwent endorectal multiparametric magnetic resonance imaging (MRI) of the prostate with DTI. Tract mapping was accomplished by positioning spherical regions of interest contiguously along the prostatic capsule at the prostatic apex, midgland, and base.

RESULTS

DTI tractography of the prostate effectively visualized periprostatic fiber tract anatomy. There was no significant correlation between total tract number and prostate size, however (Spearman's coefficient = 0.33, P = .42). Variation in tract distribution existed. The total fiber mass was highest in the lower prostate hemisphere at the base of the prostate (mean = 36.9 vs 21.1, P = .0004) and in the upper hemisphere at the apex (mean = 41.6 vs 57.9, P = .006).

CONCLUSION

DTI tractography successfully visualized fiber tracts around the prostate. Gold standard anatomic correlation is needed.

Intrafascial dissection significantly increases positive surgical margin and biochemical recurrence rates after robotic-assisted radical prostatectomy

INTRODUCTION

Improved visualization and magnification in robot-assisted laparoscopic radical prostatectomy (RALRP) has tempted many urologists to dissect the neurovascular bundle closer to the prostate following the layers of the pseudo-capsule of the prostate. This might bear a higher risk of decreased tumor control.

MATERIALS AND METHODS

An analysis of a consecutive series of 186 patients who underwent RALRP at our institution was performed. The outcome of patients with intrafascial nerve-sparing (INS) was compared with the outcome of patients who underwent interfascial, extrafascial or no nerve-sparing (non-INS).

RESULTS

A total of 80 patients (43.0%) received INS. The overall R1 rate was 27.9%. For pT2 tumors the rate of R1 was 33.8% in INS versus 14.8% in non-INS (odds ratio 2.936, 95% confidence interval 1.338-6.443, p = 0.007). Recurrence-free survival was significantly shorter in INS (p = 0.05; hazard ratio 3.791).

CONCLUSION

The intrafascial dissection technique for RALRP bears a high risk of incomplete resection in localized prostate cancer resulting in unfavorable outcome.

Suprahyoid neck fascial configuration, especially in the posterior compartment of the parapharyngeal space: a histological study using late-stage human fetuses

The fascial configuration in the suprahyoid parapharyngeal space was evaluated using semiserial sagittal sections of 15 late-stage human fetal heads. The prevertebral fascia covered the longus colli, longus capitis, and rectus capitis lateralis muscles, but was most evident along the longus colli muscle. The carotid sheath and its extension were located around the internal and external carotid arteries and the lower cranial nerves. The superior cervical ganglion was also inside the sheath. Even near full term, the fetal suprahyoid neck was short, with the jugular foramen and hypoglossal canal located at the posterolateral side of the oropharynx. Thus, the glossopharyngeal and accessory nerves ran across the upper part of the carotid sheath. Fasciae of the stylopharyngeus, styloglossus, and stylohyoideus muscles were attached to and joined the anterosuperior aspect of the carotid sheath. All these neurovascular and muscle sheaths are communicated with the visceral fascia covering the pharynx at multiple sites, and, together, they formed a mesentery-like bundle. This communication bundle was made narrow by the anteriorly protruding longus capitis muscle. The mesentery-like bundle was covered by the posterior marginal fascia of the prestyloid compartment of the parapharyngeal space. The external carotid artery ran on the lateral and posterior sides of the posterior marginal fascia. Consequently, the typical carotid sheath configuration was modified by muscle sheaths from the styloid process, communicated with the visceral fascia and, anteriorly, constituted the posterior margin of the prestyloid space.

Robotic radical prostatectomy: The new gold standard

Objectives

Open radical prostatectomy (RP) has been the standard and primary treatment for focal prostate cancer. However, in recent years this view has changed, as robot-assisted laparoscopic RP has gained acceptance among urologists. In this review we evaluate the importance and place of robotics in laparoscopic urological surgery, discussing several techniques that are currently being used and potentially new techniques that might be used in the future.

Methods

We systematically reviewed papers published between 1998 and 2011 using the keywords ‘robotic prostatectomy’ ‘gold standard’ and the Medline database. In addition, after selecting relevant reports we searched ‘related citations’ of the documents to find further supporting published papers.

Results

In all, 50 original papers were identified using the search criteria; we also found 28 through ‘related citations’ browsing. Papers were selected according to their relevance to the current topic (i.e. RP, original articles) and incorporated into this review. These papers were used for their information on the advantages of using robotics, as well as innovative ideas being used in the field of robotic urological surgery.

Conclusion

Almost a decade after the first robotic RP many reports show the benefits and advantages of incorporating robotics into urological surgery. Robotic surgery decreases the learning curve necessary for surgeons when compared with laparoscopic techniques. In addition, patients prefer robotics, as the procedure is less invasive, diminishes the duration of hospitalisation and speeds the return to function.

Surgical management of neurovascular bundle in uterine fibroid pseudocapsule

The uterine fibroid pseudocapsule is a fibro-neurovascular structure surrounding a leiomyoma, separating it from normal peripheral myometrium. The fibroid pseudocapsule is composed of a neurovascular network rich in neurofibers similar to the neurovascular bundle surrounding a prostate. The nerve-sparing radical prostatectomy has several intriguing parallels to myomectomy. It may serve either as a useful model in modern fibroid surgical removal, or it may accelerate our understanding of the role of the fibrovascular bundle and neurotransmitters in the healing and restoration of reproductive potential after intracapsular myomectomy. Surgical innovations, such as laparoscopic or robotic myomectomy applied to the intracapsular technique with magnification of the fibroid pseudocapsule surrounding a leiomyoma, originated from the radical prostatectomy method that highlighted a careful dissection of the neurovascular bundle to preserve sexual functioning after prostatectomy. Gentle uterine leiomyoma detachment from the pseudocapsule neurovascular bundle has allowed a reduction in uterine bleeding and uterine musculature trauma with sparing of the pseudocapsule neuropeptide fibers. This technique has had a favorable impact on functionality in reproduction and has improved fertility outcomes. Further research should determine the role of the myoma pseudocapsule neurovascular bundle in the formation, growth, and pathophysiological consequences of fibroids, including pain, infertility, and reproductive outcomes.

Neurovascular bundle in fibroid pseudocapsule and its neuroendocrinologic implications

The myoma pseudocapsule is a surgical-anatomical entity surrounding the fibroid that separates the myoma from normal uterine tissue. The myoma pseudocapsule has a delicate vascular network rich with neurotransmitters analogous to the neurovascular bundle surrounding the prostate. The pseudocapsule neurovascular bundle is extremely important during myomectomy to promote uterine myometrial healing and, consequently, for uterine reproductive function. New advancements in surgery, including the use of laparoscopic myomectomy by an intracapsular technique and magnification of the myoma pseudocapsule to enhance visualization are comparable to the dissection during a radical prostatectomy. Fibroid detachment occurring inside the pseudocapsule causes less bleeding, spares the neurovascular bundle and promotes better uterine healing. The maintenance of myometrial integrity after laparoscopic myomectomy maintains uterine function and therefore improves reproductive outcomes, including labor.

Classification of the distribution of cavernous nerve fibers around the prostate by intraoperative electrical stimulation during laparoscopic radical prostatectomy

We investigated the distribution of cavernous nerve (CN) fibers around the prostate by electrical nerve stimulation during laparoscopic radical prostatectomy to classify the distribution of the CN fibers. Electrical stimulation was performed on 30 consecutive patients with localized prostate cancer; middle of the neurovascular bundle (NVB, point A), base of the NVB (point B), the rectal wall 1 cm posterolateral to the NVB (point C) and the lateral aspect of the prostate (point D). We measured the intraurethral pressure at the midportion to detect the changes in intracavernosal pressure. The mean maximum changes were 10.5 ± 7.9, 11.6 ± 8.8, 9.6 ± 7.4 and 6.7 ± 7.0 cm H(2)O at points A, B, C and D, respectively. The patterns of CN fiber distribution were divided into four groups: type 1 (23%), the bundle corresponding to the NVB; type 2 (7%), the bundle from the rectal wall to the prostate; type 3 (27%), the plate including NVB and posterolateral to NVB; and type 4 (43%), the plate between the rectal wall posterolateral to the NVB and the lateral aspect of the prostate. Distribution of the CNs in a bundle-like formation was considered to account for 30%, whereas a plate-like formation accounted for 70%. Understanding these four patterns of CN fiber distribution should facilitate accurate CN-sparing radical prostatectomy.

Effect of elbow and forearm position on contact pressure between the extensor origin and the lateral side of the capitellum

PURPOSE

Bone-to-tendon contact in the origin of the common extensor tendons is considered to be one of the causes of lateral epicondylitis. Some factors, including elbow and forearm position, varus stress to the elbow, or contraction of the wrist extensor tendons, are considered to affect this bone-to-tendon contact. However, no studies have evaluated the effect of the elbow and forearm position on bone-tendon interface. The purpose of this study is to evaluate the effect of the position of the elbow and forearm on the contact pressure of the tendinous origin of the common wrist and finger extensors.

METHODS

We used 8 fresh cadaveric upper extremities. Contact pressure between the origin of the common extensor tendons and the lateral side of the capitellum was measured with a pressure sensor and was compared among various conditions, including elbow flexion angle (0°, 30°, 60°, and 90°), forearm rotation position (neutral and 81.5° pronation position), and varus stress load of the elbow (none, gravity on the forearm, and gravity on the forearm +1.96 Nm). Contact pressure was also measured during tension force of the extensor carpi radialis longus, extensor carpi radialis brevis, and extensor digitorum communis by 0, 9.8, and 19.6 N.

RESULTS

Contact pressure was significantly increased with the elbow extension position, forearm pronation position, and varus stress to the elbow under tension of the extensor carpi radialis longus or extensor carpi radialis brevis.

CONCLUSIONS

This study provides data about the amount of contact pressure between bone and tendon at the origin of the common extensor tendons in the elbow. This information may lead to a better understanding of, and better treatment for, lateral epicondylitis.

Intrafascial nerve-sparing radical prostatectomy with a laparoscopic robot-assisted extraperitoneal approach: early oncological and functional results

OBJECTIVE

We investigated whether an intrafascial approach to prostatectomy would provide significantly improved outcomes compared with retropubic and laparoscopic approaches. We performed 50 radical prostatectomies with an intrafascial, nerve-sparing, laparoscopic, robot-assisted extraperitoneal approach.

METHODS

From December 2007 to June 2008, 50 consecutive patients underwent nerve sparing surgery using the intrafascial technique with robotic assistance. All surgeries were performed by the same senior urologist. Patient characteristics and perioperative data were collected prospectively. Oncological outcomes were assessed by pathological examination and postoperative prostate-specific antigen levels. Functional outcomes, including continence, potency, and quality of life, were assessed from patient questionnaires.

RESULTS

The mean operative time was 127 minutes (range: 80-205), the mean hospital stay was 4.2 days (range: 2-9), and the mean catheterization time was 7.8 days (range: 4-11). No perioperative complications occurred. One patient required a transfusion at the postoperative stage. The overall positive surgical margin rate was 12%; adjusted by tumor, nodes, and metastasis stage, it was 9.5% in pT2 and 17% in pT3 disease. At the 1-month follow-up, 66% of the patients were continent (no pad), 12% presented a minimal stress urinary incontinence (1 pad), and 22% required >1 pad(s) per day. Further, 60% of patients exhibited potency (erection sufficient for intercourse: 30% without the use of phosphodiesterase 5 inhibitors, 30% required a phosphodiesterase 5 inhibitor) and the remaining 40% required prostaglandin injections.

CONCLUSIONS

An intrafascial approach with robotic assistance provided satisfactory early functional results with respect to postoperative continence and potency. Long-term oncological results remain to be assessed.

Neuroanatomical study of periprostatic nerve distributions using human cadaver prostate

We investigated the distribution and navigation of periprostatic nerve fibers and constructed a 3-dimensional model of nerve distribution. A total of 5 cadaver specimens were serially sectioned in a transverse direction with 0.5 cm intervals. Hematoxylineosin staining and immunohistochemical staining were then performed on whole-mount sections. Three representative slides from the base, mid-part, and apex of each prostate were subsequently divided into 4 sectors: two lateral, one ventral, and one dorsal (rectal) part. The number of nerve fibers, the distance from nerve fiber to prostate capsule, and the nerve fiber diameters were analyzed on each sector from the representative slides by microscopy. Periprostatic nerve fibers revealed a relatively even distribution in both lateral and dorsal parts of the prostate. There was no difference in the distances from the prostate capsule to nerve fibers. Nerve fibers in the ventral area were also thinner as compared to other areas. In conclusion, periprostatic nerve fibers were observed to be distributed evenly in the periprostatic area, with the exception of the ventral area. As the number of nerve fibers on the ventral part is fewer in comparison, an excessive high up incision is insignificant during the nerve-sparing radical prostatectomy.

The significance of a positive bladder neck margin after radical prostatectomy: the American Joint Committee on Cancer Pathological Stage T4 designation is not warranted

PURPOSE

The American Joint Committee on Cancer currently designates invasion of the bladder neck as a pT4 lesion. However, retrospective analyses have not demonstrated biochemical recurrence-free survival after radical prostatectomy to be consistent with other T4 lesions. We examined biochemical recurrence-free survival and cancer specific survival in men with a positive bladder neck margin.

MATERIALS AND METHODS

Of nearly 17,000 patients in the Johns Hopkins Institutional radical prostatectomy database (1982 to 2008) 198 (1.2%) were identified with a positive bladder neck margin. Kaplan-Meier analyses were used to evaluate biochemical recurrence-free survival and cancer specific survival. A multivariate proportional hazards model predicting biochemical recurrence-free survival and cancer specific survival was fit with prostate specific antigen, Gleason sum and pathological stage to determine the significance of a positive bladder neck margin.

RESULTS

Of the 198 men with a positive bladder neck margin 79 had an isolated bladder neck margin without seminal vesicle or lymph node involvement. The 12-year biochemical recurrence-free survival of men with organ confined disease, extraprostatic extension, seminal vesicle invasion and lymph node involvement without a positive bladder neck margin was 91.1%, 61.1%, 24.5% and 8.1%, respectively. For men with a positive bladder neck margin and those with an isolated positive bladder neck margin biochemical recurrence-free survival was 16.8% and 37.1%, respectively. The 12-year cancer specific survival for men with organ confined disease, extraprostatic extension, seminal vesicle invasion and lymph node involvement without a positive bladder neck margin was 93.5%, 89.0%, 77.0% and 66.8%, respectively. For men with a positive bladder neck margin and those with an isolated positive bladder neck margin cancer specific survival was 78.2% and 92.5%, respectively. A positive bladder neck margin was not a significant predictor of outcome (p = 0.4) on multivariable analysis.

CONCLUSIONS

The incidence of an isolated positive bladder neck margin is low. Men with an isolated positive bladder neck margin after radical prostatectomy experienced a 12-year biochemical recurrence-free survival of 37% and cancer specific survival of 92%, similar to patients with seminal vesicle invasion (pT3b) and extraprostatic extension (pT3a), respectively. The existing American Joint Committee on Cancer classification for prostate cancer should be reconsidered.