Cavermap-assisted sural nerve interposition graft during radical prostatectomy

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.

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.

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.

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.

Efficacy of sildenafil citrate in men with erectile dysfunction following radical prostatectomy: a systematic review of clinical data

INTRODUCTION

Radical prostatectomy is a frequently used treatment option for prostate cancer; however, prostatectomy is often associated with significant morbidity, including erectile dysfunction (ED).

AIM

To analyze the efficacy of sildenafil citrate in treating ED after radical prostatectomy.

MATERIALS AND METHODS

MEDLINE and CANCERLIT (1998 to January 2004) were searched for English language articles using the key words prostatectomy, sildenafil, and phosphodiesterase inhibitors. Eleven studies fulfilled the inclusion criteria: primary, discrete data sets of postprostatectomy patients with ED treated with sildenafil monotherapy.

RESULTS

Sample sizes ranged from 13 to 198 (mean age, 61 +/- 3 years). Treatment durations were 4 weeks (or more than four doses) to 1 year, and sildenafil dosing was in the recommended range (25-100 mg). Seven studies reported a response rate (range, 14%-53%) for an end point consistent with the primary analysis outcome (erection sufficient for vaginal intercourse); the combined estimate of probability of response was 35% (95% confidence interval [CI], 24%-48%). There was strong evidence for a lower response rate after non-nerve-sparing (range, 0%-15%) versus nerve-sparing surgery (range, 35%-75%; combined odds ratio [OR] = 12.1; 95% CI, 5.5-26.6) but not after unilateral (range, 10%-80%) versus bilateral nerve-sparing surgery (range, 46%-72%; combined OR = 2.21; 95% CI, 0.75-6.54).

CONCLUSIONS

The results of these studies demonstrate that with sildenafil, more than one third of patients with postprostatectomy ED achieved erection sufficient for intercourse. The odds of responding improved 12-fold with preservation of at least one neurovascular bundle. Early treatment failure does not necessarily imply lack of efficacy in the future, and patients should be encouraged to continue trying sildenafil, titrating up to 100 mg as needed.

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.

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).

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.

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.

Erectile function after radical prostatectomy: a review

OBJECTIVES

Although the high rate of erectile dysfunction (ED) following prostatectomy is well recognised, the aetiology and pathophysiology have not yet been fully elucidated. We examined the current literature as to aetiology, treatment and possible prevention of ED following prostatectomy.

METHOD

Review of the literature by a Medline search.

CONCLUSION

The most important predictors of erectile function are pre-operative erectile function and the nerve sparing nature of the procedure. The former is determined by age and vascular risk-factors whereas the latter is decided by the stage of the tumour and the skill of the surgeon. The value of intraoperative nerve mapping seems limited and the importance of nerve grafting is uncertain. Natural recovery of erection can take as long as 24 months. Patients complain about a lack of professional support. Symptomatic therapy may be applied according to the current general standards of treatment in men with ED.