INTERPOSITION OF SURAL NERVE RESTORES FUNCTION OF CAVERNOUS NERVES RESECTED DURING RADICAL PROSTATECTOMY

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.

Interpositional Nerve Grafting of the Prostatic Plexus after Radical Prostatectomy

Background:

Injury to the prostatic plexus may occur during radical prostatectomy even with the use of minimally invasive techniques. Reconstruction of these nerves by interpositional nerve grafting can be performed to reduce morbidity. Although the feasibility of nerve reconstruction has been shown, long-term functional outcomes are mixed, and the role of nerve grafting in these patients remains unclear.

Methods:

A retrospective study was performed on 38 consecutive patients who underwent immediate unilateral or bilateral nerve reconstruction after open prostatectomy. Additionally, 53 control patients who underwent unilateral, bilateral, or non–nerve-sparing open prostatectomy without nerve grafting were reviewed. Outcomes included rates of urinary continence, erections sufficient for sexual intercourse, and ability to have spontaneous erections. Analysis was performed by stratifying patients by D’Amico score and laterality of nerve involvement.

Results:

Unilateral nerve grafting conferred no significant benefit compared with unilateral nerve-sparing prostatectomy. Bilateral nerve-sparing patients demonstrated superior functional outcomes compared with bilateral non–nerve-sparing patients, whereas bilateral nerve-grafting patients displayed a trend toward functional improvement. With increasing D’Amico score, there was a trend toward worsening urinary continence and erectile function regardless of nerve-grafting status.

Conclusions:

In the era of robotic prostatectomy, interpositional nerve reconstruction is not a routine practice. However, the substantial morbidity experienced in patients with bilateral nerve resections remains unacceptable, and therefore, nerve grafting may still improve functional outcomes in these patients. Further investigation is needed to improve the potential of bilateral nerve grafting after non–nerve-sparing prostatectomy.

Landmarks in erectile function recovery after radical prostatectomy

The description of the nerve-sparing technique of radical prostatectomy by Walsh was one of the major breakthroughs in the surgical treatment of prostate cancer in the 20(th) century. However, despite this advance and consequent technological refinements to nerve-sparing surgery, a large proportion of men still suffer from erectile dysfunction (ED) as a complication of prostatectomy. A plethora of therapeutic approaches have been proposed to optimize erectile function recovery in these patients. Several preclinical and translational studies have shown benefits of therapies including PDE5 inhibitor (PDE5I) treatment, immunomodulation, neurotrophic factor administration, and regenerative techniques, such as stem cell therapy, in animal models. However, most of these approaches have either failed to translate to clinical use or have yet to be studied in human subjects. Penile rehabilitation with PDE5Is is currently the most commonly used clinical strategy, in spite of the absence of solid clinical evidence to support its use.

Three-year outcomes of recovery of erectile function after open radical prostatectomy with sural nerve grafting

INTRODUCTION

Optimal oncologic control of higher stage prostate cancers often requires sacrificing the neurovascular bundles (NVB) with subsequent postoperative erectile dysfunction (ED), which can be treated with interposition graft using sural nerve.

AIMS

To examine the long term outcome of sural nerve grafting (SNG) during radical retropubic prostatectomy (RRP) performed by a single surgeon.

METHODS

Sixty-six patients with clinically localized prostate cancer and preoperative International Index of Erectile Function (IIEF) score >20 who underwent RRP were included. NVB excision was performed if the risk of side-specific extra-capsular extension (ECE) was >25% on Ohori' nomogram. SNG was harvested by a plastic surgeon, contemporaneously as the urologic surgeon was performing RRP. IIEF questionnaire was used pre- and postoperatively and at follow-up.

MAIN OUTCOME MEASURES

Postoperative IIEF score at three years of men undergoing RRP with SNG. Recovery of potency was defined as postoperative IIEF-EF domain score >22.

RESULTS

There were 43 (65%) unilateral SNG and 23 (35%) bilateral SNG. Mean surgical time was 164 minutes (71 to 221 minutes).The mean preoperative IIEF score was 23.4+1.6. With a mean follow-up of 35 months, 19 (28.8%) patients had IIEF score >22. The IIEF-EF scores for those who had unilateral SNG and bilateral SNG were 12.9+4.9 and 14.8+5.3 respectively. History of diabetes (P=0.001) and age (P=0.007) negatively correlated with recovery of EF. 60% patients used PDE5i and showed a significantly higher EF recovery (43% vs. 17%, P=0.009).

CONCLUSIONS

SNG can potentially improve EF recovery for potent men with higher stage prostate cancer undergoing RP. The contemporaneous, multidisciplinary approach provides a good quality graft and expedited the procedure without interrupting the work-flow.

Emerging tools for erectile dysfunction: a role for regenerative medicine

Erectile dysfunction (ED) is the most common sexual disorder reported by men to their health-care providers and the most investigated male sexual dysfunction. Currently, the treatment of ED focuses on 'symptomatic relief' of ED and, therefore, tends to provide temporary relief rather than providing a cure or reversing the cause. The identification of a large population of "difficult-to-treat" patients has triggered researchers to identify novel treatment approaches, which focus on cure and restoration of the underlying cause of ED. Regenerative medicine has developed extensively in the past few decades and preclinical trials have emphasized the benefit of growth factor therapy, gene transfer, stem cells and tissue engineering for the restoration of erectile function. Development of clinical trials involving immunomodulation in postprostatectomy ED patients and the use of maxi-K channels for gene therapy are illustrative of the advances in the field. However, the search for novel treatment targets and a wealth of preclinical studies represent a dynamic and continuing field of enquiry.

Tissue engineering and stem cells: basic principles and applications in urology

To overcome problems of damaged urinary tract tissues and complications of current procedures, tissue engineering (TE) techniques and stem cell (SC) research have achieved great progress. Although diversity of techniques is used, urologists should know the basics. We carried out a literature review regarding the basic principles and applications of TE and SC technologies in the genitourinary tract. We carried out MEDLINE/PubMed searches for English articles until March 2010 using a combination of the following keywords: bladder, erectile dysfunction, kidney, prostate, Peyronie's disease, stem cells, stress urinary incontinence, testis, tissue engineering, ureter, urethra and urinary tract. Retrieved abstracts were checked, and full versions of relevant articles were obtained. Scientists have achieved great advances in basic science research. This is obvious by the tremendous increase in the number of publications. We divided this review in two topics; the first discusses basic science principles of TE and SC, whereas the second part delineates current clinical applications and advances in urological literature. TE and SC applications represent an alternative resource for treating complicated urological diseases. Despite the paucity of clinical trials, the promising results of animal models and continuous work represents the hope of treating various urological disorders with this technology.

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.

Randomized phase II trial evaluation of erectile function after attempted unilateral cavernous nerve-sparing retropubic radical prostatectomy with versus without unilateral sural nerve grafting for clinically localized prostate cancer

BACKGROUND

Nonrandomized studies of unilateral nerve-sparing (UNS) radical prostatectomy (RP) have reported improved recovery of erectile function if the sacrificed cavernous nerve is reconstructed with a sural nerve graft (SNG).

OBJECTIVE

To determine whether UNS RP plus SNG results in a 50% relative increase in potency at 2 yr compared to UNS RP alone.

DESIGN, SETTING, AND PARTICIPANTS

The study enrolled patients from October 2001-May 2006 from a single academic center and was randomized, open label. Participants were men with localized prostate cancer recommended for UNS RP, less than 66 yr old, normal baseline erectile function, and willing to participate in early erectile dysfunction (ED) therapy. Patients were followed up to 2 yr.

INTERVENTION

Patients underwent UNS RP and ED therapy starting at 6 wk: oral prostaglandin type-5 (PDE5) inhibitor, vacuum erection device (VED), and intracavernosal injection therapy. In the SNG group, a plastic surgeon performed the procedure at the time of RP.

MEASUREMENTS

The ability to have an erection suitable for intercourse with or without a PDE5 inhibitor at 2 yr. The hypothesis was that SNG would result in a 60% potency rate compared to 40% for controls (80% power, 5% two-way significance).

RESULTS AND LIMITATIONS

The trial planned to enroll 200 patients, but an interim analysis at 107 patients met criteria for futility and the trial was closed. For patients completing the protocol to 2 yr, potency was recovered in 32 of 45 (71%) of SNG and 14 of 21 (67%) of controls (p=0.777). By intent-to-treat analysis, potency recovered in 32 of 66 (48.5%) of SNG and 14 of 41 (34%) of controls (p=0.271). No differences were seen in time to potency or quality of life scores for ED and urinary function. Limitations included slower-than-expected accrual and poor compliance with ED therapy: <65% for VED and <40% for injections.

CONCLUSIONS

The addition of SNG to a UNS RP did not improve potency at 2 yr following surgery.

TRIAL REGISTRATION

ClinicalTrials.gov, Identifier: NCT00080808, http://www.clinicaltrials.gov/ct2/show/NCT00080808?term=NCT00080808&rank=1.

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.

Cavernous nerve regeneration using acellular nerve grafts

INTRODUCTION

The restoration of erectile function following complete transection of nerve tissue during surgery remains challenging. Recently, graft procedures using sural nerve grafts during radical prostatectomy have had favorable outcomes, and this has rekindled interest in the applications of neural repair in a urologic setting. Although nerve repair using autologous donor graft is the gold standard of treatment currently, donor nerve availability and the associated donor site morbidity remain a problem. In this study, we investigated whether an "off-the-shelf" acellular nerve graft would serve as a viable substitute. We examined the capacity of acellular nerve scaffolds to facilitate the regeneration of cavernous nerve in a rodent model.

MATERIALS AND METHODS

Acellular nerve matrices, processed from donor rat corporal nerves, were interposed across nerve gaps. A total of 80 adult male Sprague-Dawley rats were divided into four groups. A 0.5-cm segment of cavernosal nerve was excised bilaterally in three of the four groups. In the first group, acellular nerve segments were inserted bilaterally at the defect site. The second group underwent autologous genitofemoral nerve grafts at the same site, and the third group had no repair. The fourth group underwent a sham procedure. Serial cavernosal nerve function assessment was performed using electromyography (EMG) at 1 and 3 months following initial surgery. Histological and immunocytochemical analyses were performed to identify the extent of nerve regeneration.

RESULTS

Animals implanted with acellular nerve grafts demonstrated a significant recovery in erectile function when compared with the group that received no repair, both at 1 and 3 months. EMG of the acellular nerve grafts demonstrated adequate intracavernosal pressures by 3 months (87.6% of the normal non-injured nerves). Histologically, the retrieved regenerated nerve grafts demonstrated the presence of host cell infiltration within the nerve sheaths. Immunohistochemically, antibodies specific to axons and Schwann cells demonstrated an increase in nerve regeneration across the grafts over time. No organized nerve regeneration was observed when the cavernous nerve was not repaired.

CONCLUSION

These findings show that the use of nerve guidance channel systems allow for accelerated and precise cavernosal nerve regeneration. Acellular nerve grafts represent a viable alternative to fresh autologous grafts in a rodent model of erectile dysfunction.

Nerve Advancement with End-to-End Reconstruction after Partial Neurovascular Bundle Resection:A Feasibility Study

BACKGROUND AND PURPOSE

It is clear that some patients with prostate cancer require a total or partial neurovascular bundle (NVB) resection for oncologic safety to be guaranteed. Nerve grafting is an alternative for these patients to maintain erectile function; however, we report on a feasible option where the NVB is released, and both terminal nerve fibers are approximated; this is the "nerve advancement technique (NAT)."

PATIENTS AND METHODS

Since 2005, a total of 215 men aged 48 to 70 years (mean 59 years) with a Sexual Health Inventory for Men (SHIM) score of 22 have undergone robotic radical prostatectomy for cancer. We selected prospectively seven men to have NAT performed because of clinical high-risk criteria (serum prostate specific antigen [PSA] concentration >20 mg/dL, Gleason score = 8, and stage cT(2c) or higher), intraoperative criteria (difficulty separating the tissues around the prostate), and evidence of extracapsular extension (ECE) on magnetic resonance imaging. We performed unilateral partial resection, nerve advancement, and, finally, end-to-end anastomosis in six patients, whereas in one patient, we did a bilateral partial excision. We analyzed the results in terms of oncologic safety (positive surgical margins and PSA) and SHIM score after 18 months of follow-up.

RESULTS

Pathologic examination revealed stage T3 disease in six patients; one had a positive surgical margin. Two patients are receiving salvage radiotherapy for PSA relapse, and five continue to have undetectable PSA concentrations after a median follow-up of 20 months. Five of the seven men recovered erectile potency with or without a phosphodiesterase inhibitor, and their median SHIM score is 18.

CONCLUSIONS

We are encouraged by the initial results of NAT. The procedure may be an alternative for men who require extensive NVB dissection. However, further experience, longer follow-up, and independent trials are necessary.

Preliminary Report of the Effect of High-Dose Adjuvant Intensity Modulated Radiation Therapy on the Sural Nerve Graft for Cavernosal Nerve Sacrifice After Radical Prostatectomy

PURPOSE

A sural nerve graft may replace a killed cavernosal nerve. The effect of intensity-modulated radiation therapy (IMRT) on function of the graft has not been reported.

MATERIALS AND METHODS

Between 1998 and 2001, 8 patients (9 nerve grafts) were treated with postoperative IMRT (mean dose, 70 Gy). Two patients had neoadjuvant Lupron 30 mg 2 months prior to radiation. Potency was defined as ability to achieve spontaneous erection sufficient for vaginal penetration. Median follow-up was 31.6 months.

RESULTS

Five patients (62.5%) who had erectile function after prostatectomy preserved spontaneous erectile function after radiation. Of these, 3 patients had both nerves resected (two receiving unilateral grafts and one receiving bilateral grafts) and 2 others had one graft and one nerve preserved. The impotent patients were impotent after surgery.

CONCLUSION

High-dose postprostatectomy IMRT does not place sural nerve grafts at greater risk for failure. Larger numbers of patients are needed to confirm these encouraging, preliminary findings.

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.

Impact of unilateral interposition sural nerve graft on the recovery of sexual function after radical prostatectomy in Japanese men: a preliminary study

PURPOSE

To determine the effect of an interposition nerve graft on sexual function after radical prostatectomy.

METHODS

This study includes 64 patients, without hormonal therapy, who underwent a radical prostatectomy and intraoperative electrophysiological confirmation of cavernous nerve preservation. Twelve patients underwent a unilateral interposition sural nerve graft (UNG) for the resected neurovascular bundle. Twenty-one and 31 patients underwent bilateral nerve-sparing (BNS) and unilateral nerve-sparing (UNS) surgery without a nerve graft, respectively. As the age of patients was significantly younger in the UNG group than in the other groups, age-matched analysis also was conducted. Sexual function, evaluated by a self-administered questionnaire using the University of California Los Angeles-Prostate Cancer Index, was compared statistically among the three groups.

RESULTS

In the age-matched analysis, the postoperative sexual function (SXF) score of the UNG group showed an intermediate level of recovery between those of the BNS and UNS groups at 12 months and reached the same level as the score at 12 months of the BNS group at 18 months postoperatively. The difference in the SXF score between the UNG and UNS groups began to appear after 6 months postoperatively and increased steadily with time. However, the background factors, such as the baseline SXF score, the usage rate of phosphodiesterase 5 inhibitors, and the rate of comorbidities were different between the UNG and UNS groups.

CONCLUSIONS

The difference of the SXF score between the UNG and UNS groups increased with time after 6 months postoperatively. However, it might be difficult at present to attribute a better recovery of the SXF score to the nerve graft because of the difference in the background factors between the groups.

Bilateral Cavernous Nerve Interposition Grafting During Radical Retropubic Prostatectomy: Memorial Sloan-Kettering Cancer Center Experience

PURPOSE

Cavernous nerve graft is an option for men requiring bilateral cavernous nerve resection for cancer control during radical prostatectomy. We determined the success rate and identified determinants of success of bilateral cavernous nerve grafting following resection of the 2 nerves during radical prostatectomy in patients who were potent preoperatively.

MATERIALS AND METHODS

We retrospectively reviewed the records of 44 consecutive patients who underwent bilateral nerve grafting from 1999 to 2004. Postoperative erectile function was defined as the achievement of erections satisfactory for intercourse with or without oral medication. We calculated cumulative erectile function recovery rates using Kaplan-Meier curves. The log rank test was used to compare variables affecting erectile function recovery with p <0.0083 considered significant after adjusting for the number of variables evaluated using the Bonferroni correction.

RESULTS

The overall 5-year cumulative recovery of erectile function permitting penetration was 34% and the rate of consistent penetration was 11%. None of the analyzed variables were significantly associated with recovery of postoperative erectile function, including patient age (p = 0.3), incomplete bilateral cavernous nerve resection (p = 0.045), sural nerve grafts compared to genitofemoral or ilioinguinal nerves as donor sites (p = 0.067), post-radiation salvage radical prostatectomy (p = 0.15), neoadjuvant hormone therapy (p = 0.7) and comorbidities (p = 0.15) or medications (p = 0.4) affecting EF.

CONCLUSIONS

Bilateral cavernous nerve grafts might be beneficial in select patients. A definitive answer awaits the performance of a multi-institutional, randomized, controlled trial.

Two-year outcome of unilateral sural nerve interposition graft after radical prostatectomy

OBJECTIVES

To study 41 men treated for prostate cancer with unilateral nerve-sparing radical prostatectomy and contralateral sural nerve grafting from January 2000 to September 2003.

METHODS

Patients were considered for sural nerve grafting if they were considered at high risk of extracapsular extension before or during surgery, were younger than 70 years of age with good preoperative erectile function, were sexually active, and had no significant risk factors for erectile dysfunction. Potency was assessed by patient-reported questionnaires, including the International Index of Erectile Function erectile domain and Rigiscan testing.

RESULTS

The mean follow-up was 27.4 +/- 14.5 months. At 24 months, 24 (63.2%) of 38 men had erections sufficient for intercourse, with or without phosphodiesterase type 5 inhibitor use. Four men had partial erections that were occasionally satisfactory (10.5%), and 10 men reported no sexual activity, no spontaneous erections, or partial erections unsatisfactory for intercourse (26.3%). In contrast, in a group of 49 men who underwent unilateral nerve-sparing prostatectomy without nerve grafting during the same period at our institution, 13 (26.5%) had rigid erections adequate for intercourse with or without phosphodiesterase type 5 inhibitor use at 24 months of follow-up.

CONCLUSIONS

At 24 months of follow-up, men who had undergone unilateral nerve-sparing prostatectomy with contralateral sural nerve interposition graft repair of a cut cavernosal nerve had a greater rate of return of erectile function than men undergoing unilateral nerve-sparing prostatectomy alone.

Recovery of sexual function after prostate cancer treatment

PURPOSE OF REVIEW

The estimated disease-free survival rates are approximately equivalent across standard treatments for localized prostate cancer. We aim to review the efforts being made to reduce posttreatment erectile dysfunction, a major morbidity of these therapies.

RECENT FINDINGS

Potency as an important factor in a patient's decision about choosing a form of therapy has been demonstrated in the literature. For nerve-sparing surgery, though some proponents of laparoscopic radical prostatectomy believe it may confer an advantage over the open surgical techniques, the published data is scarce and has yet to demonstrate a true difference. Enthusiasm has declined for sural nerve grafting because of the associated complexity of the procedure and inconsistent results. Concurrent implantation of a penile prosthesis is an option for certain patients who already have some baseline erectile dysfunction or are not candidates for nerve-sparing surgery. Agents such as phosphodiesterase inhibitors, immunophilin ligands, and recombinant human erythropoietin have demonstrated potential benefits in early reports of both in-vitro and ongoing clinical trials.

SUMMARY

Currently, no standard treatment or prophylaxis exists for posttreatment erectile dysfunction. Neuro-protective and regenerative therapies, including the immunophilin ligands, hold promise to reduce the morbidity of localized prostate cancer therapy.

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.

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.

Erectile dysfunction and treatment of carcinoma of the prostate

Prostate cancer is the leading malignancy in men in the United States and causes more than 60,000 deaths annually. Treatment of prostate cancer, whether it be with surgery, radiation therapy, cryotherapy, or medical treatment, is associated with significant life-altering morbidity. Incontinence and erectile dysfunction (ED) too often are sequelae of these treatment alternatives. ED can be a significant complication and can alter the life of the patient with prostate cancer and his partner. Newer modifications of the radical prostatectomy with nerve-sparing techniques are the cornerstone of erection preservation. Time following radical prostatectomy has been shown to increase erectile function such that more patients have functional erections at 3 years than 1 year after surgery. With the advent of phosphodiesterase-5 (PDE-5) inhibitors, many men can have improved functional erections and return to active coitus. Prevention of ED also is an important management technique. Evidence is gathering that prophylaxis with regular vasoactive injection or daily PDE-5 agents may be an integral part of preservation of corpus cavernosum smooth muscle function. Combination medical therapy and surgical penile prosthesis implantation also are options for patients who do not respond to oral PDE-5 inhibitors.

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.

Evaluation of Genitofemoral Nerve Donor Site Morbidity After Radical Prostatectomy

BACKGROUND

The sural nerve is commonly used as a donor site for cavernous nerve grafting. However, the genitofemoral nerve is accessible and easily dissected and may represent an improved donor site for this procedure.

METHODS

Fourteen patients underwent radical prostatectomy followed by cavernous nerve grafting using the genitofemoral nerve. Seventeen donor sites (3 patients underwent bilateral grafts) were assessed by questionnaires (including the McGill Pain Scale) and focused neurologic examination.

RESULTS

Residual numbness in the genitofemoral nerve distribution was noted in 9 of 17 donor sites (53%). No patients reported that the deficits interfered with normal daily activities. All patients denied the presence of burning, cold sensitivity, or pain. All patients scored 0 on each of the 3 pain rating components of the short form McGill Pain questionnaire (sensory, affective, or total). Furthermore, no patients documented pain on either the PPI or VAS portions of the questionnaire. On examination, patients were unable to discriminate between sharp versus dull stimuli in 3 donor sites (17.6%), while 7 donor sites (41.2%) showed decreased light-touch sensation. The Semmes-Weinstein testing demonstrated that 8 (47.1%) were found to have distinct areas with sensory deficit ranging in size from 23 to 63 cm (mean, 16.6 cm). The highest-pressure thresholds for each of the 17 donor sites ranged from 3.61 to 6.45 g/mm (mean, 4.91 g/mm). The mean pressure threshold for the control regions (n=11) was 3.35 g/mm (range, 2.38--4.71 g/mm, P=0.014). Only 50% of the sensory deficits documented by the Semmes-Weinstein test were clinically apparent to the patients.

CONCLUSIONS

Due to its low donor site morbidity, the genitofemoral nerve is an excellent donor source for cavernous nerve grafting during radical prostatectomy. In the majority of the patients, the sensory deficit produced by resection of this nerve is minimal and caused no other adverse symptoms. Harvest of this nerve prevents the additional morbidity associated with a donor site located elsewhere on the body (ie, sural nerve).

LAPAROSCOPIC RADICAL PROSTATECTOMY

PURPOSE

After the pioneering period when only few teams were performing the procedure, the laparoscopic approach to radical prostatectomy has become widespread with several technical variations. A comprehensive review of the published literature on laparoscopic radical prostatectomy was performed to determine the current state of the art of this surgical innovation in terms of perioperative parameters, functional results and cancer control.

MATERIALS AND METHODS

English language, peer reviewed articles published before June 2004 concerning laparoscopic radical prostatectomy were found by MEDLINE query. All articles were analyzed and none were a priori excluded. Conclusions were drawn from series of 50 or more patients.

RESULTS

Laparoscopic radical prostatectomy is being performed at multiple centers worldwide using various surgical approaches and technologies. Analysis of perioperative parameters, including surgical blood loss, operative time, complications and convalescence, demonstrated low morbidity and showed a clear trend toward improvement with increased experience. The reported positive surgical margin rates were lower in more recent series. As measured by prostate specific antigen recurrence and disease-free intervals, oncological results and cancer control rates are difficult to ascertain in the immature series published to date. Functional results in terms of postoperative urinary and sexual function appear encouraging.

CONCLUSIONS

Overall the current operative, oncological and functional results of laparoscopic radical prostatectomy appear to approximate those of open radical retropubic prostatectomy. These results justify the considerable interest of the urological community in laparoscopy, as evidenced by its widespread application. Nevertheless, longer followup and more mature data are needed definitively to establish laparoscopic radical prostatectomy as an alternative to the retropubic approach.

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.

The impact of surgical approach (nerve bundle preservation versus wide local excision) on surgical margins and biochemical recurrence following radical prostatectomy

PURPOSE

Surgical margin (SM) status is widely reported as a significant risk factor for prostate cancer recurrence following radical prostatectomy (RP). It has been presupposed that preserving the neurovascular bundle may compromise cancer control due to the limited surgical margin obtained with a resultant increase in treatment failure. We examined whether neurovascular bundle preservation during RP is a risk factor for positive SMs and progression-free survival after adjusting for disease severity.

MATERIALS AND METHODS

Outcomes following RP in 7,268 men between 1990 and 2000 were examined retrospectively. Median followup in those last known to be alive is 6.4 years. RP was performed by a total of 21 surgeons in the same basic fashion with strict attention to anatomical detail.

RESULTS

Overall a positive SM was identified in 38% of patients. The positive SM rate was higher for wide excision than for nerve sparing (NS) (42% vs 34%) (p </= 0.001). The OR for positive SMs in patients undergoing NS-RP was 0.86 (95% CI 0.76 to 0.97, p = 0.012) after incorporating age, clinical stage, biopsy grade, year of surgery and prostate specific antigen. Similarly NS-RP had no significant impact on biochemical progression rates after controlling for these variables (HR 0.98, 95% CI 0.88 to 1.08, p = 0.64).

CONCLUSIONS

NS-RP is not an independent adverse risk factor for positive SMs or progression-free survival. Tumor biology appears set prior to technically skilled anatomical radical prostatectomy independent of wide excision of the neurovascular bundles. All patients with organ confined prostate cancer should be considered candidates for an NS operation.

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.

Schwann cell seeded guidance tubes restore erectile function after ablation of cavernous nerves in rats

PURPOSE

Dissection of the cavernous nerves eliminates spontaneous erections. We evaluated the ability of Schwann cell seeded nerve guidance tubes to restore erections after bilateral cavernous nerve resection in rats.

MATERIALS AND METHODS

Sections (5 mm) of the cavernous nerve were excised bilaterally, followed by immediate bilateral microsurgical reconstruction. In 10 animals per group (20 study nerves) reconstruction was performed by genitofemoral nerve interposition, interposition of silicone tubes or interposition of silicone tubes seeded with homologous Schwann cells. As the control 10 animals (20 study nerves) underwent sham operation (positive control) and bilateral nerve ablation (without reconstruction) was performed in a further 10 (negative control). Erectile function was evaluated 3 months postoperatively by relaparotomy, electrical nerve stimulation and intracavernous pressure recording.

RESULTS

After 3 months neurostimulation resulted in an intact erectile response in 90% (18 of 20) of Schwann cell grafts, while treatment with autologous nerves (30% or 6 of 20) or tubes only (50% or 10 of 20) was less successful (p <0.01). Whereas untreated ablated rats showed no inducible erections (0% or 0 of 20), all sham operated animals had an intact erectile response (100% or 20 of 20). Maximum intracavernous pressure upon electrostimulation was significantly elevated using Schwann cell grafts compared to results in the other treatment groups (p <0.001). Morphological evaluation revealed advanced regeneration within Schwann cell grafts.

CONCLUSIONS

Schwann cell seeded guidance tubes restore erectile function after the ablation of cavernous nerves in rats and they are superior to autologous nerve grafts.

Impact of unilateral interposition sural nerve grafting on recovery of urinary function after radical prostatectomy

OBJECTIVES

To test the hypothesis that unilateral sural nerve graft (SNG) interposition may improve the rate of urinary function (UF) recovery after radical retropubic prostatectomy (RRP) in patients undergoing unilateral nerve resection (UNR).

METHODS

We studied 111 consecutive patients who underwent RRP with purposeful UNR performed by a single surgeon. Of the 111 patients, 53 underwent unilateral SNG interposition. All patients were invited to complete a questionnaire that included the validated University of California, Los Angeles, Prostate Cancer Index. The time to UF recovery above the median value of the group and urinary control status were evaluated.

RESULTS

The median follow-up was 26 and 12 months for the UNR and UNR+SNG patients, respectively. At 12 months after RRP, 94.7% of patients with UNR+SNG reported having complete urinary control or leakage of only a few drops of urine compared with 58.3% of patients with UNR alone (P = 0.012). In multivariate Cox regression models, UNR+SNG was associated with a 9.95 times greater rate of reaching a UF score above the median versus UNR alone (P <0.001). In multivariate logistic regression analyses, SNG status increased the odds of having complete urinary control or leakage of only a few drops of urine by 14.99 and 29.19 at 6 and 12 months after RRP, respectively (both P <0.05).

CONCLUSIONS

In patients undergoing UNR surgery, SNG interposition is associated with a greater rate of UF recovery and a higher likelihood of urinary control after RRP. These findings need to be validated in larger, multicenter, prospective, randomized studies.

RESTORATION OF EXTERNAL URETHRAL SPHINCTER FUNCTION AFTER PUDENDAL NERVE END-TO-END ANASTOMOSIS IN THE MALE RABBIT

PURPOSE

In this study we rehabilitated external urethral sphincter function by pudendal nerve end-to-end anastomosis after experimental pudendal nerve axotomy in male rabbits.

MATERIALS AND METHODS

A total of 17 animals were included in this study, including group 1-a control group of 5 (29.4%), group 2-6 (35.3%) and group 3-6 (35.3%). Animals from group 2 underwent bilateral axotomy and group 3 underwent pudendal nerve end-to-end anastomosis. In all groups we performed urodynamic investigations prior to axotomy, after axotomy or anastomosis, and 14, 42 and 90 days after axotomy or nerve anastomosis.

RESULTS

In untreated group 1 control sphincter pressure was 28.5 cm H2O. In group 2 average urethral sphincter pressure was 5.6 cm H2O 14 days after axotomy with only a slight increase to 11.05 cm H2O by day 90. In group 3 external urethral pressure increased to 8.26 cm H2O after 14 days and to 21.32 cm H2O by postoperative day 90.

CONCLUSIONS

External urethral sphincter deficiency after bilateral pudendal nerve axotomy demonstrates the primacy of the pudendal nerve in the innervation of the external urethral sphincter. We were able to rehabilitate external urethral sphincter function by performing pudendal nerve end-to-end anastomosis.

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.

Feasibility of Radical Prostatectomy After Neoadjuvant Chemohormonal Therapy for Patients With High Risk or Locally Advanced Prostate Cancer: Results of a Phase I/II Study

PURPOSE

We determined the feasibility of radical prostatectomy after neoadjuvant chemohormonal therapy in locally advanced (stage T3 or greater) and/or high risk tumors (Gleason 8 to 10 and/or serum prostate specific antigen (PSA) greater than 20 ng/ml).

MATERIALS AND METHODS

Enrollment criteria included clinical stage T1 to 2 with any Gleason grade and PSA greater than 20 ng/ml, clinical stage T3 to 4 with any serum PSA or Gleason grade, or any clinical stage with biopsy Gleason grade of 8 to 10 and any serum PSA. All patients received neoadjuvant hormonal therapy during chemotherapy (4 cycles of paclitaxel and carboplatin and estramustine) followed by radical prostatectomy. Nerve sparing was decided on an individual basis and a nerve graft was offered to those who underwent unilateral or bilateral nerve resection. Perioperative morbidity, mortality and delayed complications were assessed.

RESULTS

A total of 36 patients were enrolled. After chemohormonal therapy clinical stage was less in 39% of patients and greater in 36%. Bilateral nerve sparing was performed in 3 patients and the remaining 33 underwent either unilateral or bilateral neurovascular bundle resection with nerve grafts performed in 17 (52%). Deep vein thrombosis (22%) was the most frequent complication of chemotherapy. Minor postoperative complications occurred in 6 patients. At a median followup of 29 months (range 5 to 51) after radical prostatectomy 32 (89%) were continent and 5 (15%) preoperatively potent men remained potent. The positive surgical margin rate was 22%. Of all subjects 45% remain free from biochemical recurrence.

CONCLUSIONS

Neoadjuvant chemohormonal therapy followed by radical prostatectomy can be performed with low morbidity. Positive surgical margin rates are low. This approach yielded good local control of disease, however impact on tumor recurrence and survival is not known.