Cavernous nerve graft reconstruction during radical prostatectomy or radical cystectomy: safe and technically feasible

Regenerative technology to restore and preserve erectile function in men following prostate cancer treatment: evidence for penile rehabilitation in the context of prostate cancer survivorship

Introduction

Erectile dysfunction (ED) following prostate cancer treatment is not uncommon and penile rehabilitation is considered the standard of care in prostate cancer survivorship (PCS), where both patient and his partner desire to maintain and/or recover pre-treatment erectile function (EF). There is a clinical interest in the role of regenerative therapy to restore EF, since existing ED treatments do not always achieve adequate results.

Aim

To review regenerative therapies for the treatment of ED in the context of PCS.

Materials and Methods

A review of the existing PubMed literature on low-intensity extracorporeal shockwave therapy (LIESWT), stem cell therapy (SCT), platelet-rich plasma (PRP), gene therapy, and nerve graft/neurorrhaphy in the treatment of ED and penile rehabilitation, was undertaken.

Results

IESWT promotes neovascularization and neuroprotection in men with ED. While several systematic reviews and meta-analyses showed positive benefits, there is limited published clinical data in men following radical prostatectomy. Cellular-based technology such as SCT and PRP promotes cellular proliferation and the secretion of various growth factors to repair damaged tissues, especially in preclinical studies. However, longer-term clinical outcomes and concerns regarding bioethical and regulatory frameworks need to be addressed. Data on gene therapy in post-prostatectomy ED men are lacking; further clinical studies are required to investigate the optimal use of growth factors and the safest vector delivery system. Conceptually interpositional cavernous nerve grafting and penile re-innervation technique using a somatic-to-autonomic neurorrhaphy are attractive, but issues relating to surgical technique and potential for neural 'regeneration' are questionable.

Conclusion

In contrast to the existing treatment regime, regenerative ED technology aspires to promote endothelial revascularization and neuro-regeneration. Nevertheless, there remain considerable issues related to these regenerative technologies and techniques, with limited data on longer-term efficacy and safety records. Further research is necessary to define the role of these alternative therapies in the treatment of ED in the context of penile rehabilitation and PCS.

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.

Penile rehabilitation after pelvic cancer surgery

Erectile dysfunction is the most common complication after pelvic radical surgery. Rehabilitation programs are increasingly being used in clinical practice but there is no high level of evidence supporting its efficacy. The principle of early penile rehabilitation stems from animal studies showing early histological and molecular changes associated with penile corporal hypoxia after cavernous nerve injury. The concept of early penile rehabilitation was developed in late nineties with a subsequent number of clinical studies supporting early pharmacologic penile rehabilitation. These studies included all available phosphodiesterase type 5 inhibitors, intracavernosal injection and intraurethral use of prostaglandin E1 and to lesser extent vacuum erectile devices. However, these studies are of small number, difficult to interpret, and often with no control group. Furthermore, no studies have proven an in vivo derangement of endothelial or smooth muscle cell metabolism secondary to a prolonged flaccid state. The purpose of the present report is a synthetic overview of the literature in order to analyze the concept and the rationale of rehabilitation program of erectile dysfunction following radical pelvic surgery and the evidence of such programs in clinical practice. Emphasis will be placed on penile rehabilitation programs after radical cystoprostatectomy, radical prostatectomy, and rectal cancer treatment. Future perspectives are also analyzed.

Therapeutic effect of adipose-derived stem cells and BDNF-immobilized PLGA membrane in a rat model of cavernous nerve injury

INTRODUCTION

Cavernous nerve injury is the main reason for post-prostatectomy erectile dysfunction (ED). Stem cell and neuroprotection therapy are promising therapeutic strategy for ED.

AIM

To evaluate the therapeutic efficacy of adipose-derived stem cells (ADSCs) and brain-derived neurotrophic factor (BDNF) immobilized Poly-Lactic-Co-Glycolic (PLGA) membrane on the cavernous nerve in a rat model of post-prostatectomy ED. Methods.  Rats were randomly divided into five groups: normal group, bilateral cavernous nerve crush injury (BCNI) group, ADSC (BCNI group with ADSCs on cavernous nerve) group, BDNF-membrane (BCNI group with BDNF/PLGA membrane on cavernous nerve) group, and ADSC/BDNF-membrane (BCNI group with ADSCs covered with BDNF/PLGA membrane on cavernous nerve) group. BDNF was controlled-released for a period of 4 weeks in a BDNF/PLGA porous membrane system.

MAIN OUTCOME MEASURES

Four weeks after the operation, erectile function was assessed by detecting the ratio of intra-cavernous pressure (ICP)/mean arterial pressure (MAP). Smooth muscle and collagen content were determined by Masson's trichrome staining. Neuronal nitric oxide synthase (nNOS) expression in the dorsal penile nerve was detected by immunostaining. Phospho-endothelial nitric oxide synthase (eNOS) protein expression and cyclic guanosine monophosphate (cGMP) level of the corpus cavernosum were quantified by Western blotting and cGMP assay, respectively.

RESULTS

In the ADSC/BDNF-membrane group, erectile function was significantly elevated, compared with the BCNI and other treated groups. ADSC/BDNF-membrane treatment significantly increased smooth muscle/collagen ratio, nNOS content, phospho-eNOS protein expression, and cGMP level, compared with the BCNI and other treated groups.

CONCLUSIONS

ADSCs with BDNF-membrane on the cavernous nerve can improve erectile function in a rat model of post-prostatectomy ED, which may be used as a novel therapy for post-prostatectomy ED.

Guideline for optimization of surgical and pathological quality performance for radical prostatectomy in prostate cancer management: evidentiary base

BACKGROUND

The objective is to provide surgical and pathological guidelines for radical prostatectomy (RP) with or without concurrent pelvic lymph node dissection (PLND) to achieve optimal benefit for patients, with minimal risk of harm.

METHODS

For surgical questions, a literature search of MEDLINE, EMBASE and the Cochrane database was performed. A literature search for the pathological questions was not conducted since the protocol for invasive carcinomas of the prostate gland developed by the College of American Pathologists (CAP) was endorsed. Urologists and pathologists were consulted for their assessment of the surgical and pathological recommendations.

RESULTS

Limited high-quality evidence from 95 primary studies was available and, therefore, the expert panel developed recommendations on the basis of a consensus of the expert opinion of the working group and through a consultation with urologists and pathologists. In addition to the CAP protocol, some technical recommendations related to the handling and processing of the specimen were made.

CONCLUSION

Radical prostatectomy is recommended for the surgical treatment of prostate cancer, depending on a patient's preoperative risk profile. The panel unanimously determined that the goals for RP are to attain a positive margin rate of <25% for pT2 disease, a mortality rate of <1%, rates of rectal injury of <1% and blood transfusion rates of <10% in non-anemic patients. Standard PLND should be mandatory in high-risk patients, should be recommended for intermediate-risk patients and should be optional for low-risk patients. The quality and effectiveness of this treatment and of subsequent patient care depend on good management, effective communication and reporting between surgeons and pathologists working together as part of a multidisciplinary team. The complete guideline document is posted on the Cancer Care Ontario website (www.cancercare.on.ca); search in their Toolbox, Quality Guidelines & Standards, Clinical Program category under "surgery."

Histologic and electrophysiological study of nerve regeneration using a polyglycolic acid-collagen nerve conduit filled with collagen sponge in canine model

OBJECTIVES

To determine the rate of achieving electrophysiologically proved functional recovery by autonomic nerve regeneration, with the aid of an artificial nerve conduit.

METHODS

A polyglycolic acid (PGA) collagen nerve conduit filled with collagen sponge was interposed in a 10-mm-long gap of the right hypogastric nerve (HGN) in 16 dogs. Histologic evaluation of nerve regeneration and electrophysiological analysis at 2 weeks and 2, 3, 4, 5, 6, 7, and 8 months (n = 2, each) after surgery was performed, measuring the responses for the spermatic ducts (SD), bladder neck (BN), and prostate contraction, by stimulating the right lumbar splanchnic nerves (LSNs) from L2 to L4, after transection of the left HGN to eliminate substitutive pathways.

RESULTS

Two months after implantation, the regenerated neurofilaments were successfully extended through the graft from the proximal-to-distal direction. In 2 control dogs, electrostimulation of the right LSNs induced elevation of the intraluminal pressure of the SD, elevation of the BN pressure, and prostate contraction. No responses were observed in all dogs up to 6 months of follow-up after implantation. In 1 dog with a 7-month follow-up, electrostimulation elicited elevation of BN pressure alone. In both dogs with an 8-month follow-up, electrostimulation induced similar responses to control in all SD, BN, and prostate; however, after excision of the area of the interposed right HGN, no response was observed.

CONCLUSIONS

These results proved that regeneration of a 10-mm gap of the HGN, using a novel PGA-collagen nerve conduit could be achieved within 8 months.

Interposition nerve grafting during radical prostatectomy: cumulative review and critical appraisal of literature

In 1997, the first report of sural nerve interposition grafting during radical prostatectomy was published in Urology. The favorable findings in this initial pilot study generated numerous follow-up reports that have demonstrated conflicting and contradictory outcomes. Certainly, controversy exists regarding the true benefit of nerve grafting. This review will objectively and critically summarize the salient literature, discuss evolving techniques, and offer insight into the future of interposition grafting in the current era of clinically localized prostate cancer and robotic prostatectomy.

Recovery of erectile function after unilateral and bilateral cavernous nerve interposition grafting during radical pelvic surgery

PURPOSE

The use of cavernous nerve interposition grafting to preserve erectile function in men who require neurovascular bundle resection for cancer control is controversial. We report outcomes and predictors of cavernous nerve interposition grafting in men undergoing unilateral grafting during radical prostatectomy or bilateral grafting during radical cystectomy and prostatectomy with autologous nerve grafts.

MATERIALS AND METHODS

We retrospectively reviewed the electronic records of 36 patients who underwent cavernous nerve interposition grafting between 2003 and 2006. Postoperatively erectile function was assessed with the International Index of Erectile Function 15-item questionnaire. Predictors of potency, including age at surgery, time since surgery and prostate specific antigen at surgery, were assessed by univariate analysis.

RESULTS

A total of 33 patients (92% response rate) were followed for a median of 32, 25 and 11 months after bilateral grafting during radical cystectomy (10), unilateral grafting during radical prostatectomy (20), and bilateral grafting during radical cystectomy and prostatectomy (3), respectively. The rate of potency, defined as the ability to attain and maintain erection sufficient for penetration at least 50% of the time with or without phosphodiesterase-5 inhibitors, was 31% (5 of 13 men) for unilateral grafts, 38% (5 of 16) for bilateral grafts and 30% (3 of 10) for bilateral grafts during radical cystectomy. Age at surgery was the only significant determinant of potency and it showed an inverse relationship in the bilateral nerve graft group (p = 0.02).

CONCLUSIONS

Cavernous nerve interposition grafting appears to have a role in the recovery of erectile function. To our knowledge this study represents the largest series of cavernous nerve interposition grafting during cystectomy and it suggests that this should be considered during bilateral neurovascular bundle resection.

Interventions for sexual dysfunction following treatments for cancer

BACKGROUND

The proportion of people living with and surviving cancer is growing. This has led to increased awareness of the importance of quality of life including sexual function in people with cancer. Sexual dysfunction (SD) is a potential long-term complication of cancer treatments.

OBJECTIVES

Evaluate effectiveness of interventions for SD following treatments for cancer and their adverse effects.

SEARCH STRATEGY

The Cochrane Pain, Palliative & Supportive Care Register, Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, PsycInfo, AMED, CINAHL, Dissertation Abstracts and NHS Research Register were searched.

SELECTION CRITERIA

Randomised controlled trials (RCTs) were included that assessed the effectiveness of a treatment for SD. The trial population comprised of adults of either sex who at trial entry had developed SD as a consequence of cancer treatment.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted the data and assessed trial quality. Meta-analysis was considered for trials with comparable key characteristics.

MAIN RESULTS

Eleven RCTs with a total of 1743 participants were identified. The quality of the trials was poor. Ten trials explored interventions for SD in men following treatments for non-metastatic prostate cancer. One trial explored effectiveness in women of a lubricating vaginal cream following radiotherapy for cervical cancer. The strongest evidence (from four trials) was on oral phosphodiesterase type 5 (PDE5) inhibitors for erectile dysfunction (ED) following radiotherapy of the prostate or radical prostatectomy. The results using validated measures in all trials significantly favoured those in the PDE5 inhibitor group(s). The combined results of two trials indicated a significantly greater improvement in ED in the PDE5 inhibitor groups (odds ratio (OR) 10.09 95% confidence interval (CI) 6.20 to 16.43). Negative effects were few and usually mild to moderate headaches or flushing. One trial reported more clinically serious events including six events of tachycardia and six of chest pain. Following prostate cancer treatments there was some evidence that PDE5 inhibitors are more effective in combination with acetyl-L-carnitine and propionyl-L-carnitine and that sexual counselling improves self-administration of prostaglandin intra-cavernous injection for SD. There was some evidence following treatment for prostate cancer that transurethral alprostadil and vacuum constriction devices reduce SD, although in both trials negative effects were fairly common. There is some evidence that vaginal lubricating creams reduce SD.

AUTHORS' CONCLUSIONS

PDE5 inhibitors are an effective treatment for SD secondary to treatments for prostate cancer. Other interventions identified need to be tested in further RCTs. The SD interventions in this review are not representative of the range available for men and women. Further evaluations are needed for these interventions for SD following cancer treatments.

Results of unilateral genitofemoral nerve grafts with contralateral nerve sparing during radical prostatectomy

OBJECTIVES

To evaluate the success of erectile function preservation and recovery in a select group of patients with extensive disease unilaterally on biopsy who were candidates for unilateral nerve sparing and contralateral genitofemoral interposition nerve-grafting radical prostatectomy (RP). Because of its low donor site morbidity, the genitofemoral nerve is an appealing donor source for cavernous nerve grafting during RP. Although evidence has shown that sural interposition nerve grafts during RP preserve erectile function, the evidence for genitofemoral nerve grafts is limited.

METHODS

Nerve-sparing RP was performed according to the technique of Walsh on 22 patients with prostate cancer. At follow-up, the patients completed an 11-item self-report questionnaire that included the erectile function (EF) domain of the International Index of Erectile Function.

RESULTS

The mean patient age was 62 years (range 48 to 76). The mean follow-up time was 23 months (range 9 to 37). Of the 22 patients, 3 reported no erectile dysfunction (ED) (EF score 26 to 30), 3 reported mild ED (EF score 22 to 25), 1 reported moderate ED (EF score 11 to 16), and 15 reported severe ED (EF score less than 11). Eight men continued to experience mild chronic thigh or scrotal numbness after the genitofemoral nerve graft procedure.

CONCLUSIONS

The benefits of unilateral nerve grafting with the genitofemoral nerve remain uncertain. A prospective randomized trial is warranted before the widespread adoption of unilateral nerve grafting.

Dissociation of sexual function and sexual bother following autologous sural nerve grafting during radical prostatectomy

AIM

We prospectively investigated health-related quality of life (HR-QOL), including sexual function and sexual bother, in patients who underwent nerve grafting during a radical prostatectomy in comparison with those who underwent a non-nerve-sparing radical prostatectomy.

METHODS

Between August 2001 and May 2004, radical prostatectomies were performed on 69 patients with clinical T1-T2N0/M0 prostate cancer. Of these, 66 patients (22: nerve-grafting patients, 44: non-nerve-sparing and non-nerve-grafting patients) were enroled into this study. The observation periods ranged from 12-46 months (median: 29 months). The general HR-QOL was measured with the SF-36 General Health Survey and disease-specific HR-QOL was measured with the University of California Los Angeles-Prostate Cancer Index.

RESULTS

Penile tumescence was observed in 11 out of 15 (73.3%) prostate-specific antigen failure-free patients who underwent unilateral nerve grafting with contra-lateral nerve-sparing or bilateral nerve grafting. Vaginal penetration was observed in six out of 15 (40.0%) patients. The time for partial erection and for intercourse, respectively, ranged from 3-21 months (median = 6 months) and 6-36 months (median = 13.5 months). There were no significant differences in general HR-QOL changes over time between the nerve-grafting patients and the patients without any nerve-preserving procedures. The sexual function score was significantly better in the nerve-grafting (bilateral nerve graft or unilateral nerve graft with contra-lateral nerve-sparing) patients than in the non-nerve-sparing/non-nerve-grafting patients. The sexual bother score, however, was more serious for the patients who underwent nerve-grafting surgery than for the non-nerve-sparing/non-nerve-grafting patients.

CONCLUSION

Sexual bother is serious for patients who attempt to maintain sexual function after special surgical procedures, such as nerve-grafting surgery. We should be aware that careful counseling is needed to avoid impatient and excessive hope for the recovery of sexual function.

Cavernous nerve graft reconstruction using an autologous nerve guide to restore potency

OBJECTIVE

To present our experience of cavernous nerve graft reconstruction, using an autologous nerve vein-guide technique, to restore potency.

PATIENTS AND METHODS

Prostate cancers frequently require radical resection involving one or both cavernous nerves that usually results in erectile dysfunction; nerve grafting has been used to restore erectile function, but clinical results are unsatisfactory owing to inadequate surgical techniques. In all, eight patients with prostate cancer who required radical resection involving one cavernous nerve had sural nerve grafting, with two or three sutures using the autologous vein-guide technique, in our unit between 2004 and 2005. Because of the difficulty of performing microsurgical manoeuvres deep within the pelvic cavity, the nerve anastomosis might be unsatisfactory.

RESULTS

Seven of the eight patients had spontaneous erectile activity after grafting and six of these patients were able to have intercourse.

CONCLUSION

Sural nerve grafting using the autologous vein-guide technique is simple, has minimal morbidity, and yields good outcomes.

Reconstruction of cavernous nerves by nerve grafts to restore potency: contemporary review of technical principles and basic anatomy

PURPOSE OF REVIEW

The review discusses the efficacy of reconstructing the neurovascular bundle to regain sexual function if nerve-sparing prostatectomy is unfeasible.

RECENT FINDINGS

Eleven studies could be found describing the reconstruction of neurovascular bundles. All reconstructive procedures displayed technical inadequacies. The effectiveness of unilateral neurovascular bundle reconstruction remains statistically insignificant when compared with procedures without reconstruction. The efficacy of reconstructing both neurovascular bundles ranges between 0 and 43%. Concerning basic anatomy, the neurovascular bundle contains fibers innervating the cavernous nerves, prostate, rectum, and levator ani muscle. The terms cavernous nerve and neurovascular bundle have often been wrongly considered synonymous. The pelvic splanchnic nerves probably do not join the neurovascular bundle proximal to the bladder/prostate junction but rather at variable distances from 10 to 20 mm distal to it. Therefore, described proximal coaptation sites at the bladder/prostate junction possibly encompass only the hypogastric nerve.

SUMMARY

Modest clinical results are partly due to inadequate surgical techniques and are mainly due to the anatomical and topographical complexity of the cavernous nerves. Contemporary nerve grafting techniques probably do not allow for the regeneration of all cavernous nerves.

Effects of chronic bacterial prostatitis on prostate specific antigen levels total and free in patients with benign prostatic hyperplasia and prostate cancer

BACKGROUND

Prostatic-specific antigen (PSA), a tumor marker helpful in the diagnosis and follow-up of prostate cancer, may rise due to causes such as prostatitis, chronic benign prostatic hyperplasia (BHP), etc. The aim of this study was to investigate the relationship between prostatitis and the level of total and free prostate-specific antigen in patients with no clinical evidence of prostate cancer.

METHODS

A comprehensive urological examination was performed on 156 patients aged 35-61 years old. All patients have symptoms of prostatitis. Prostate fluid culture was preformed. All patients underwent a course of antibacterial treatment after which the levels of total prostate specific antigen (TPSA) and free prostate specific antigen (FPSA) were evaluated.

RESULTS

An increase in TPSA (> 4 ng/ml) was observed in 14/24 (58.3%) patients with acute prostatitis and in 7/45 (15.5%) and 4/44 (9.1%) in patients with chronic bacterial prostatitis (CBP) and a bacterial prostatitis, respectively. Low blood concentration of TPSA and FPSA were observed after effective antibacterial and anti-inflammatory treatment therapy in most cases.

CONCLUSION

These data suggested that prostatitis must be considered when interpretation of TPSA and FPSA values as tumor marker.

The Effects of Cavernous Nerve Grafting following Surgically Induced Loss of Erectile Function in a Large-Animal Model

BACKGROUND

Prostate cancer is the second most common cause of cancer deaths in men in the United States. Many patients experience partial or complete loss of erectile function following prostatectomy. The cavernous nerves can be reconstructed intraoperatively using sural nerve grafts in an attempt to restore erectile function.

METHODS

In this study, multiple anatomical dissections and neurologic assessments were used to define the position and histologic parameters of the cavernous nerve in a canine model. The subsequent experimental design included three groups of adult mongrel dogs followed for an 8-month period. Group 1, the control group, underwent bilateral nerve ablation to substantiate surgically induced loss of erectile function. Group 2, the "sham" group, underwent exploration only. Group 3 underwent bilateral cavernous nerve ablation with bilateral sural nerve graft reconstruction. Erectile function was evaluated with indirect electrical nerve and manual penile stimulation preoperatively and 1, 2, 4, 6, and 8 months postoperatively. Direct nerve stimulation and histologic analysis was preformed at the first operation and at the time the animals were euthanized at 8 months.

RESULTS

Bilateral cavernous nerve ablation resulted in a significant loss of erectile function for 8 months postoperatively in the control animals. The sham animals demonstrated preservation of erectile function immediately following exploration. The animals in the grafted group demonstrated a significant return of erectile function by 4 months compared with preoperative measurements and by 2 months compared with control animals.

CONCLUSIONS

This study establishes the first large-animal model for surgically induced loss of erectile function with successful cavernous nerve graft reconstruction, and it provides the unique opportunity to explore the effects of changes to this model in the future.

Sexual dysfunction after pelvic surgery

Pelvic surgeries are among the most common causes of organic sexual dysfunction in men and women. The impact of nerve-sparing surgery on potency has been well documented in radical prostatectomy. However, its impact on potency needs to be evaluated in other pelvic surgeries. Sexual dysfunction is highly prevalent even after multiple technical advances in the field of oncological surgeries. The prevalence varies from 8 to 82%, depending on the type of pelvic surgery. In females, sexual dysfunction has not been evaluated adequately using validated questionnaires. However, in subspecialized circles, treatment for female sexual dysfunction is becoming routine. Currently, physicians have several options for the treatment of erectile dysfunction (ED) in men. Since the introduction of oral PDE-5 inhibitors, oral therapy has become the first-line treatment option for ED, irrespective of etiology. Currently available treatment options for the female sexual dysfunction include estrogens, androgens, phosphodiesterase inhibitors, and dopamine receptor antagonists. Initial reports regarding the role of early rehabilitation are encouraging and may become the part of routine practice in the management of ED after pelvic surgery. In this article, we summarize the sexual dysfunction following pelvic surgeries and their management.

Update on erectile dysfunction in prostate cancer patients

PURPOSE OF REVIEW

Evolution in the management of prostate cancer includes increased attention being paid to patient quality of life after treatment, specifically with issues related to sexual function. Erectile dysfunction is one of the major concerns of patients undergoing treatment for prostate cancer. There are several recognized factors that determine the postoperative incidence of erectile difficulties, including patient age, degree of cavernosal nerve sparing during surgery, cancer stage, and associated vascular comorbidities. Early initiation of rehabilitation protocols after radical prostatectomy has been advocated to promote the speed and degree of recovery of erectile function. The aim of this communication is to review recent initiatives in erectile dysfunction restoration after prostate cancer therapy.

RECENT FINDINGS

In recognition of the neurogenic basis of erectile dysfunction after radical prostatectomy, new strategies have been devised to initiate the rehabilitation process. Type 5 phosphodiesterase inhibitors, vacuum erection devices, and intracavernosal and intraurethral application of vasoactive agents have all been reported in a positive light in recent studies. Developments in cavernous nerve graft interposition procedures, perioperative neuroprotection measures, and postoperative neurotrophic treatments aim to preserve prostate cancer patients' qualities of life.

SUMMARY

Data generated from a number of clinical investigations document that pharmacologic rehabilitation programs provide a higher rate of recovery of erectile function following radical prostatectomy. Both intracavernosal and intraurethral applications of vasoactive agents and vacuum devices can speed the recovery period for return of erectile function. Various neuroprotective and neurotrophic approaches are thought to provide integral roles for the maintenance of sexual function in men undergoing prostate cancer therapy.

Recent neuroanatomical studies on the neurovascular bundle of the prostate and cavernosal nerves: clinical reflections on radical prostatectomy

The neurovascular bundle of the prostate and cavernosal nerves have been used to describe the same structure ever since the publication of the first studies on the neuroanatomy of the lower urogenital tract of men, studies that were prompted by postoperative complications arising from radical prostatectomy. In urological surgery every effort is made to preserve or restore the neurovascular bundle of the prostate to avoid erectile dysfunction (ED). However, the postoperative potency rates are yet to be satisfactory despite all advancements in radical prostatectomy technique. As the technology associated with urological surgery develops and topographical studies on neuroanatomy are cultivated, new observations seriously challenge the classical teachings on the topography of the neurovascular bundle of the prostate and the cavernosal nerves. The present review revisits the classical and most recent data on the topographical anatomy of the neurovascular bundle of the prostate and cavernosal nerves and their implications on radical prostatectomy techniques.

Nerve Replacement Strategies for Cavernous Nerves

OBJECTIVE

This article reviews novel restorative therapies for cavernous nerves that may be used to replace resected cavernous nerves at the time of pelvic surgery.

METHODS

A literature-based presentation (Medline search) on current nerve replacement strategies was conducted with emphasis on neurobiological factors contributing to the restoration of erectile function after cavernous nerve injuries.

RESULTS

A promising alternative to autologous nerve grafts for extending the length of successful nerve regeneration are artificial nerve guides. The addition of neurotrophic factors, extracellular matrix components and Schwann cells has been shown to promote cavernous nerve regeneration. Neurotrophic factors can be incorporated in the scaffold or can be supplied by cells seeded into the stroma. The regenerative capacity of these cells can be further enhanced by genetic modification with neurotrophic factor encoding genes.

CONCLUSIONS

Artificial nerve guides, especially biodegradable ones containing growth-promoting factors or cells, are a promising option for the repair of cavernous nerve lesions.

Establishing a robotics program

Establishing a successful robotics program requires consideration of several issues, including the surgical procedures to be performed, training and personnel, facilities, finance, and marketing. This article considers these factors from an academic health center standpoint and evaluates the benefits and risks of this new technology for urology departments.

Current concepts in the management of erectile dysfunction in men with prostate cancer

Development in the management of prostate cancer has placed increased attention on patient quality of life after treatment, particularly sexual function. The incidence of erectile dysfunction (ED) in men following radical prostatectomy has been estimated to range from 16% to 82%. Several factors determine the postoperative incidence of erectile difficulties; these include patient age, degree of cavernosal nerve sparing during surgery, cancer stage, and associated comorbidities. Early initiation of available treatments after radical prostatectomy, such as phosphodiesterase-5 (PDE-5) inhibitors and intracavernosal alprostadil, may improve the speed and degree of recovery of erectile function. Oral PDE-5 inhibitors are recognized as the first line of therapy for men with ED after radical prostatectomy, with reasonable success rates reported for all commercially available PDE-5 inhibitors. In recognition of the neurogenic basis for erectile dysfunction after radical prostatectomy, new strategies have been devised, such as cavernous nerve graft interposition procedures, perioperative neuroprotection measures, and postoperative neurotrophic treatments. Hopefully, these efforts will improve quality of life for patients with prostate cancer. The aim of this article is to review the current modalities of ED management for men with prostate cancer.

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

PURPOSE

Urologists and anatomists have disagreed concerning pelvic neurovascular bundle (NVB) structure. Recently interposition nerve grafting has been performed to improve erectile function after radical prostatectomy. To refine this procedure we reviewed NVB structure from the surgical viewpoint.

MATERIALS AND METHODS

Seven fresh cadavers and serial horizontal sections from 20 formalin fixed cadavers were used for gross dissection and histological examination.

RESULTS

Fresh cadaver dissections demonstrated that the pelvic splanchnic nerve (PSN) joined the NVB at a point distal or inferior to the bladder-prostate (BP) junction. Histologically hypogastric nerve fibers were much more dominant than PSN fibers at the BP junction, and the NVB, covered by the lateral pelvic fascia, became evident at levels more than 20 to 30 mm below the BP junction. PSN components joined the NVB in a spray-like distribution at multiple levels more than 20 mm distal to the BP junction. At these low levels nerves tended to be located outside of the NVB at the dorsolateral margin of the prostate. The cranial end of the mimic interposition nerve graft was directed toward the hypogastric nerve rather than the PSN.

CONCLUSIONS

In contrast to general clinical opinion, the NVB appears to supply few PSN components at the BP junction with caudal PSN branches reaching the dorsolateral prostate more than 20 mm below the BP junction. This anatomy has important implications for a reliable nerve graft.

Current and Future Strategies for Preventing and Managing Erectile Dysfunction Following Radical Prostatectomy

INTRODUCTION AND OBJECTIVES

As radical prostatectomy remains a commonly used procedure in the treatment of clinically localized prostate cancer, we critically analyzed current and future strategies for preventing and managing postoperative erectile dysfunction.

METHODS

Systematic literature review using Medline and CancerLit from January 1997 to June 2003. Abstracts published in the journals European Urology, The Journal of Urology and the International Journal of Impotence Research as official proceedings of internationally known scientific societies held in the same time period were also assessed.

RESULTS

Patient selection and surgical technique are the major determinants of postoperative erectile function. Apoptosis of corporeal smooth muscle cells plays a role in the development of cavernous veno-occlusive dysfunction following radical prostatectomy. Pharmacological prophylaxis and treatment of postoperative erectile dysfunction is effective and safe. The concepts of cavernous nerve reconstruction and neuroprotection have been associated to promising results.

CONCLUSIONS

In the hands of experienced surgeons, properly selected patients undergoing a nerve sparing radical prostatectomy should achieve unassisted or medically assisted erections postoperatively.