Interstitial high-dose-rate brachytherapy as salvage treatment for locally recurrent prostate cancer after definitive radiation therapy: Toxicity and 5-year outcome.

PURPOSE: We report our results with interstitial high-dose-rate brachytherapy (HDR-BT) as a salvage therapy option after external beam therapy with or without BT. Emphasis was put on toxicity and 5-year outcome. METHODS AND MATERIALS: From 2003 to 2011, 29 patients with local failure after previous radiotherapy for prostate cancer were treated with salvage interstitial HDR-BT. The diagnosis of local recurrence was made on the basis of choline positron emission tomography. Salvage HDR-BT was given in three fractions with a single dose of 10 Gy per fraction and weekly. The target volume covered the peripheral zone of the prostate and the positron emission tomography-positive area. Acute and late toxicities were documented according to common terminology criteria for adverse events (CTCAE v 4.0). RESULTS: Twenty-two patients with minimum followup of 60 months were analyzed. The 5-year overall survival was 95.5% with a disease-specific survival of 100%. The 5-year biochemical control was 45%. Late grade 2 gastrointestinal toxicities were observed in two patients (9%). No grade 3 or higher gastrointestinal late toxicities were observed. Urinary incontinence found in 2 patients (9%) and grade 2 obstruction of urinary tract occurred in one patient (4%). CONCLUSIONS: Interstitial HDR-BT was feasible and effective in the treatment of locally recurrent prostate cancer after definitive radiotherapy. The long-term toxicity was low and acceptable.

Reliability of dynamic sentinel node biopsy combined with ultrasound-guided removal of sonographically suspicious lymph nodes as a diagnostic approach in patients with penile cancer with palpable inguinal lymph nodes.

INTRODUCTION AND OBJECTIVES: Dynamic sentinel node biopsy (DSNB) is considered "unsuitable" in patients with penile cancer and palpable inguinal lymph nodes. The aim of this study was to determine the diagnostic reliability of DSNB combined with ultrasound (US)-guided removal of additional suspicious lymph nodes as a minimally invasive diagnostic approach in these patients. MATERIAL AND METHODS: A total of 23 consecutive patients with penile cancer and unilaterally or bilaterally palpable inguinal lymph nodes underwent DSNB according to the 2-day protocol. Before the combined staging procedure, the patients underwent preoperative US of both groins. During surgery, sentinel nodes and additional suspicious lymph nodes as determined by the US examination were removed under US guidance. A complete inguinal lymph node dissection was only performed in patients who had tumor-positive nodes. Follow-up consisted of control visits according to the European Association of Urology guidelines, including US investigation of the groins. RESULTS: The primary tumors were staged as T1, T2, and T3 carcinomas in 12, 8, and 3 patients, respectively. Grading was good, moderate, and poor in 2, 16, and 4 cases, respectively. Tumor grading could not be determined in 1 patient who underwent surgery of the invasive part of the primary tumor elsewhere. Sentinel nodes or nonsentinel nodes or both were positive in 15 of 36 palpatory-positive groins. DSNB alone showed lymphatic spread in 10 inguinal regions. US-guided removal of suspicious nonsentinel nodes revealed 5 further inguinal basins with metastases, which would have been missed by DSNB owing to rerouting or complete blockage of the lymphotropic tracer. So far, no lymph node relapse has been observed in the 12 patients with node-negative disease by this combined diagnostic approach with a median follow-up of 42 (16-84) months. The morbidity (postoperative bleeding and prolonged lymphorrhea) associated with this procedure was minor (6%). CONCLUSIONS: The results of this study imply that DSNB combined with US-guided removal of suspicious lymph nodes is a reliable diagnostic approach in patients with penile cancer with palpable inguinal lymph nodes. DSNB alone in these patients leads to a significant false-negative rate. These early and promising results have to be confirmed in larger cohort studies.

Management of recurrent post-prostatectomy incontinence after previous failed retrourethral male slings.

OBJECTIVE: Our objective was to establish the feasibility of combining 2 minimally invasive procedures in patients with failed primary treatment (male sling) in post-prostatectomy incontinence (PPI) patients. METHODS: From January 2007 to July 2008, 40 men with PPI were implanted with a suburethral tape (2 patients with Seratim, 3 with I-Stop and 35 with Advance). The median preoperative pad count was 4 (range 2-10). Prior to sling placement, 6 patients had undergone ProACT implantation. Of these, 4 patients required explantation due to balloon migration and 2 patients had their balloons kept in situ, with the balloons deflated. RESULTS: Twenty-five patients were socially continent at this time. Fifteen patients (37.5%) did not improve or their improvement was not significant. These patients had a preoperative pad count between 7 and 10. Two of these patients had prostate adjustable continence therapy (ProACT) systems still in place. By gradually filling the balloons to 3 mL, both of these patients achieved complete continence, which was maintained at a mean follow-up of 8.5 months. Three patients with prior pelvic irradiation received an artificial urinary sphincter and achieved continence at mean follow-up of 8.3 months. The remaining 10 patients received a ProACT system in addition to the already implanted sling. After appropriate healing and filling of the balloons (average balloon volume 5 mL), all 10 patients reached complete continence; they were pad-free at a mean follow-up of 6 months (range 3-9). CONCLUSIONS: The combination of ProACT and a suburethral tape was demonstrated to be a possible treatment option in recurrent or persistent PPI.

Histological detection of minimal metastatic disease in inguinal non-sentinel lymph nodes in penile cancer.

UNLABELLED: The aim of this study was to detect lymphatic spread by serial step-section technique in non-sentinel lymph nodes (NSLNs), which were earlier assessed as negative by histological examination. PATIENTS AND METHODS: Inguinal dissection specimens of 13 men with penile cancer were investigated. The LNs were sectioned at multiple levels (150 mum-intervals) and then H&E- and immuno-stained for cytokeratin (Lu-5). RESULTS: 196 LNs of 13 men were examined. In 2 out of 13 patients (15%) previously ranked as pN0, minimal lymph node involvement was detected by serial step sections and both immunohistochemistry and H&E staining. Both patients have had an uneventful follow-up of currently 62 and 16 months. CONCLUSION: Conventional histological examination of NSLNs fails to detect lymphatic spread in penile cancer. Step-section technique at 3 section levels, rather than immunohistochemistry, helps to safely detect minimal metastatic disease. The prognostic relevance is still unclear and has to be investigated in larger cohort studies.

Functional impact of the rhabdosphincter branch of the pelvic nerve on the membranous urethra in comparison to that of the pudendal nerve in male rabbits.

INTRODUCTION: The innervation of the membranous urethra (MU) is still under debate. We analysed the functional effects of electrostimulation of the rhabdosphincter branch of the pelvic nerve (RBP) on the MU in a standardized male rabbit model, paying attention both to the efferent and the possible afferent effects of stimulation. MATERIAL AND METHODS: Six male rabbits (chinchilla bastards) were included in this study. Pudendal nerve branches as well as pelvic nerve branches were exposed bilaterally in all animals. Randomized electrostimulation trials of both the pudendal nerve fibres and the RBP were carried out using a biphasic signal (0.3 mA, 200 mus). The stimulation frequency ranged from 10 to 40 Hz in a randomized pattern. Changes in MU pressure were measured urodynamically. The pressure changes occurring as a result of stimulation were compared in both nerve structures. At the end of the stimulation trial, the RBP and the pudendal nerve were dissected at different positions before repeating the stimulation and the MU pressure recording. RESULTS: The mean MU baseline pressure without stimulation was 24 cm H(2)O (range 21-27) in all animals. During unilateral pudendal stimulation, the mean pressure response rose by highly significant values (p < 0.005) compared to baseline. The pressure response was frequency dependent. Stimulation of the RBP resulted in a small but significant change of the MU pressure in the lower frequency range (10 and 20 Hz) (p > 0.05). On performing stimulation at higher frequencies, there was no significant difference from baseline. The pressure response of the MU during stimulation of the intact RBP did not differ significantly from the response after dissection of the RBP. However, after dissecting the pudendal nerve, the MU pressure response to RBP stimulation was diminished. CONCLUSION: Our results confirm the primacy of the pudendal nerve in the innervation of the MU. Stimulation of the RBP, however, may produce an afferent signal which is transmitted to the pudendal nerve, thus resulting in a pressure increase of the MU and contributing towards continence. We showed the importance of the RBP to maintain full urinary continence in rabbits. Our results suggest that substantially higher continence rates can be achieved through a nerve-sparing procedure in radical prostatectomy. Nerve-sparing radical prostatectomy incidentally also protects the RBP from injury.

Should being aged over 70 years hinder penile prosthesis implantation?

OBJECTIVE: To assess the satisfaction profiles following penile prosthesis surgery in patients with erectile dysfunction (ED) in their seventh decade of life. PATIENTS AND METHODS: In all, 174 patients received, for the first time, a penile prosthesis between 1990 and 2007 in our department. Among these, 35 patients were aged > or =70 years at prosthesis implantation. Of these, 18 patients were still alive at the time of follow-up. Using a telephone survey, patients were asked to answer the Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) as well as the International Index of Erectile Dysfunction (IIEF). Another question in the survey was developed by the authors based on a comprehensive review of the literature, which assessed the usefulness of the device for the patient and the degree of their usage. This was formulated as follows: How many times per 2 weeks do you have a sexual intercourse? RESULTS: In all, 15 of 18 patients were either very or somewhat satisfied (83%). At follow-up 11 out of 15 (73%) patients were using their prosthesis regularly. The mean IIEF and EDITS scores were 21.80 and 75.20, respectively. CONCLUSION: A penile prosthesis remains a highly promising treatment in older patients with a similar satisfaction rate to those published for younger patients. Thus, the motivation of the patient and not the age of the patient should be the main determinant factor in this surgical procedure.

Interobserver variation in grading and staging of squamous cell carcinoma of the penis in relation to the clinical outcome.

OBJECTIVE: To examine interobserver variations in assessing grade and stage of penile squamous cell carcinoma (SCC). PATIENTS AND METHODS: We retrospectively reviewed the pathological features and clinical outcome in 75 patients with SCC of the penis, who were treated in participating urological centres between 1996 and 2005; the assessments of the local pathologists and the review pathologists were compared. RESULTS: There was conformity in tumour grade in 67% and the assessment of tumour stage conformed in 84%; the combination assessment of both grade and stage conformed in 56%. CONCLUSION: Accurate histological subtyping by the surgical pathologist demands standardized guidelines, in particular for histological grading, which is crucial for clinical treatment, but shows significant interobserver variation.

Lymphatic spread in squamous cell carcinoma of the penis is independent of elevated lymph vessel density.

OBJECTIVE: To examine the potential effect of tumour-induced lymphangiogenesis in squamous cell carcinoma of the penis as a possible mechanism responsible for lymphatic spread. PATIENTS AND METHODS: Specimens from 65 patients with invasive tumours (31 with and 34 without metastases) were evaluated for lymphatic vessel density (LVD) by the 'hot-spot' method as the density of lymphatic endothelium hyaluronan receptor (LYVE-1)-positive lymphatic vessels per unit area of tissue. LVD was examined in peritumoral, intratumoral and normal tissue areas. The LVD of each tumour in these locations was calculated as the mean of the three highest lymph vessel counts in three to five hot-spots. The nodal status was based on histopathological examination or an uneventful follow-up of >or=2 years. RESULTS: In all patients the mean (SD) peritumoral LVD of 8.05 (3.14)/0.75 mm(2) was significantly higher than for intratumoral and normal tissue, of 4.67 (2.58) and 5.20 (1.87), respectively (P < 0.001). The slightly lower intratumoral LVD than in normal tissue was not significant. The peritumoral LVD was 8.07 (3.29) in metastatic and 8.03 (3.03) in non-metastatic carcinomas. The intratumoral LVD was 5.13 (3.01) in node-positive carcinomas and 4.28 (2.15) in tumours with no lymphatic node metastasis (LNM). Comparing tumours with and without LNM, there was no statistically significant difference between intra- and peritumoral LVD. CONCLUSION: Increased LVD does not significantly affect the lymphatic spread in penile carcinomas, indicating that there must be alternative mechanisms that selectively enable tumour cells to invade lymph vessels and to metastasize into the lymph nodes.

Ewing's sarcoma of the urogenital tract.

This article reviews the current available information on Ewing's sarcoma of the urogenital tract, focusing on the presentation, diagnosis, and therapeutic management of this uncommon entity. Because of the rapid local growth of these tumors, an immediate decision for treatment initiation is mandatory. The classical presentation depends mainly on the site of involvement of these tumors, involving a palpable mass, hematuria, and pain. No specific diagnostic imaging is available to date, and the only diagnostic method remains histological examination in combination with immunohistochemistry. Treatment involves primary surgical resection of all tumor tissues followed by adjuvant multi-agent chemotherapy. Overall survival is poor, although a 13-year survival has been reached in one case.

Unilateral vs bilateral sacral neuromodulation in pigs with formalin-induced detrusor hyperactivity.

OBJECTIVE: To investigate the efficacy of unilateral vs bilateral sacral neuromodulation (SNM) under standard experimental conditions by stimulating the dorsal sacral roots in pigs with formalin-induced detrusor hyperactivity. MATERIALS AND METHODS: After lumbosacral laminectomy in eight alpha-chloralose-anaesthetized Göttinger mini-pigs, the dorsal roots of the nerve S3 were inserted into separate compartments of a size-modified Brindley electrode. Detrusor hyperactivity was induced by intravesical instillation of a 0.25% formalin solution. Stimulation of the separated dorsal roots was performed on the unilateral right, respectively, the unilateral left side, as well as bilaterally and with stimulation off-phases in a randomized pattern. A biphasic rectangular signal (impulse 200 micros, 20 Hz, 2.0 V) was used for SNM. The bladder pressure values were registered on a urodynamic unit and evaluated as contractions and amplitudes per minute. RESULTS: During unilateral stimulation, the mean (sem) number of contractions was reduced significantly from 4.73 (0.66) to 2.73 (0.62). The amplitude was also reduced significantly from 12.86 (1.23) to 8.32 (0.66). By contrast, bilateral stimulation lowered the mean (sem) number of overactive detrusor contractions to 1.08 (1.02) and the amplitude to 3.08 (2.42), which are highly significant reductions. CONCLUSION: In this porcine model, bilateral neurostimulation was a more effective method of SNM than unilateral stimulation. We assume that this is due to the additive effect of stimulating both sides, as well as the greater chance of stimulating the relevant dorsal roots of the sacral nerve fibres. By contrast, unilateral neuromodulation may be only partially effective by not being capable of influencing the entire bladder, or possibly by allowing new formation of neuronal pathophysiological pathways.

Functional outcome following photoselective vaporisation of the prostate (PVP): urodynamic findings within 12 months follow-up.

OBJECTIVES: We determined the impact of potassium-titanyl-phosphate (KTP) laser therapy of the prostate on urodynamic results, voiding function, quality of life, and sexual function. DESIGN, SETTING, AND PARTICIPANTS: Forty-five patients complaining of symptomatic benign prostatic hyperplasia (BPH) and urodynamically proven obstructive voiding were included in the prospective study. Follow-up exams were repeated 3 mo and 12 mo after the treatment. INTERVENTION: All patients underwent photoselective 80-Watt KTP laser vaporisation of the prostate performed by two experienced surgeons. MEASUREMENTS: Disease-specific quality of life and sexual function were assessed using the International Prostate Symptom Score (IPSS) and International Inventory of Erectile Function (IIEF). Video-urodynamics were carried out to determine changes in pressure flow and bladder function. RESULTS AND LIMITATIONS: The average preoperative prostate volume was 47.63 ml (range 30-75 m). The mean preoperative PSA-value, which had been 3.5 ng/ml (range 0.13-7 ng/ml) initially, dropped by 34.2% after 3 mo and 37.1% after 12 mo. Despite transient micturition complaints (40%), all patients showed significant improvement in the IPSS in urinary peak flow and detrusor pressure at peak flow. The mean post-void residual urine volume decreased, while erectile function and libido scores remained unaffected by the procedure according to the IIEF. Detrusor contractility was also not affected in any of the patients. The single-centre study design and small number of patients may have limited the study results. CONCLUSIONS: KTP laser therapy of the prostate achieves significant improvements both symptomatically as well as with respect to objective micturition parameters. The procedure leads to a functional deobstruction of the lower urinary tract with steady improvement results throughout the follow up period.

Endoscopic retrieval of a penile prosthesis' rear-tip extender.

INTRODUCTION: The renewal of penile prosthesis is a foreseeable intervention because of the limited survival time of the different implants. It usually becomes necessary simply for material fatigue after long-term regular use; in some cases, premature intervention might be necessary because of infection or other perioperative complications. AIM: In the case presented here, the removal of a Dynaflex penile prosthesis showed a missing rear-tip extender on the right-hand tube. MAIN OUTCOME MEASURES AND METHODS: A cavernoscopy of the right cavernous body was performed by using a conventional urethrocystoscope. The found rear-tip extender was extracted by using alligator forceps via the cystoscopic device. RESULTS: A new AMS CX hydraulic cavernous body prosthesis was successfully implanted. It has proven fully functional up to the current follow-up control. CONCLUSIONS: This case shows that cavernoscopy is a gentle intraoperative procedure for diagnosing and removing material in penile prosthesis surgery.

Lymph-node metastases in intermediate-risk squamous cell carcinoma of the penis.

OBJECTIVE: To evaluate the metastatic risk of pT1 G2 squamous cell carcinoma (SCC) of the penis. PATIENTS AND METHODS: We retrospectively reviewed 20 patients with pT1 G2 penile SCC and determined their groin status at first presentation, their nodal status after inguinal lymph node dissection and their follow-up for at least 18 months. RESULTS: Four of the 20 patients had a clinically positive groin; three of these were found to have lymph node metastases. Among the 16 patients with a clinically negative groin, one of five who had surgical lymph node staging had lymph node metastases. During surveillance six of 11 patients developed lymph node metastases. There was lymphovascular invasion in three of 10 patients with lymph node metastases. CONCLUSIONS: As the metastatic risk of pT1 G2 penile SCC was 50% in this series of patients, and 44% in those with an initially negative groin, surgical staging of inguinal lymph nodes is recommended in patients with pT1 G2 penile SCC.

Recovery of erectile function after nerve-sparing radical prostatectomy: improvement with nightly low-dose sildenafil.

OBJECTIVE: To evaluate the effect of low-dose sildenafil for rehabilitating erectile function after nerve-sparing radical prostatectomy (NSRP), as the delay to recovery of erectile function after NSRP remains under debate. PATIENTS AND METHODS: Forty-three sexually active patients had a NSRP; at 7-14 days after surgery they had a Rigiscan (Dacomed Corporation, Minneapolis, MN, USA) measurement of nocturnal penile tumescence and rigidity (NPTR). To support the recovery of spontaneous erectile function, 23 patients with preserved nocturnal erections received sildenafil 25 mg/day at night. A control group of 18 patients were then followed but had no phosphodiesterase-5 inhibitors. The International Index of Erectile Function (IIEF)-5 questionnaire was completed 6, 12, 24, 36 and 52 weeks after NSRP. RESULTS: Of the 43 patients, 41 (95%) had one to five erections during the first night after catheter removal. In the group using daily sildenafil the mean IIEF-5 score decreased from 20.8 before NSRP to 3.6, 3.8, 5.9, 9.6 and 14.1 at 6, 12, 24, 36 and 52 weeks after NSRP, respectively. In the control group the respective scores were 21.2, decreasing to 2.4, 3.8, 5.3, 6.4 and 9.3. There was a significant difference in IIEF-5 score and time to recovery of erectile function between the groups (P < 0.001), with potency rates of 86% vs 66%. CONCLUSION: The measurement of NPTR after NSRP showed erectile function even the 'first' night after catheter removal. In cases of early penile erection, daily low-dose sildenafil leads to a significant improvement in the recovery of erectile function.

Nocturnal tumescence: a parameter for postoperative erectile integrity after nerve sparing radical prostatectomy.

PURPOSE: The exact process and time required for rehabilitation of erectile function after nerve sparing prostatectomy remain unclear to date. Different theories of the pathophysiology of postoperative erectile dysfunction are currently being discussed. In a prospective study we performed recordings of nocturnal penile tumescence and rigidity during the acute phase after nerve sparing radical prostatectomy, ie in the first night after removal of the catheter, to assess the organic penile integrity. MATERIALS AND METHODS: In 27 patients with local prostate carcinoma who had been sexually active before the intervention, we performed unilateral or bilateral nerve sparing radical prostatectomy. Preoperative sexual function of all patients was evaluated by the International Index of Erectile Function-5 questionnaire. On the day of catheter removal (postoperative day 7 to 14) an NPTR recording was performed on the following night with an erectometer (RigiScan). RESULTS: All patients had a preoperative IIEF score greater than 18. After removal of the catheter 25 of 27 patients (93%) showed 1 to 5 nocturnal rigidity increases by greater than 70% for at least 10 minutes. In a control group of 4 patients who underwent radical prostatectomy without nerve sparing, no nocturnal erections were recorded. CONCLUSIONS: NPTR recording during the acute phase after nerve sparing radical prostatectomy showed residual erectile function as early as the first night after catheter removal. These results are significant for selecting adequate pharmacological treatment for optimal therapy and rehabilitation of satisfactory erections and sexual function. In cases of early nocturnal tumescence, application of a PDE5 inhibitor can support successive organ rehabilitation. However, if tumescence does not occur, penile injection therapy is recommended.

Cortical representation of the urge to void: a functional magnetic resonance imaging study.

PURPOSE: The urge to void generally increases with bladder distention but the relationship between the 2 factors is complex. When the bladder is moderately filled, the desire to void can be called forth deliberately but it can also be suppressed. To elucidate human brain mechanisms that are active during such intentional modulations of the desire to void we performed functional magnetic resonance imaging in healthy volunteers. MATERIALS AND METHODS: Brain activity was studied in 22 young women. At moderate bladder filling (about 350 ml) they periodically suppressed or enhanced the urge to void without allowing urine to pass. A manual task with a dynamometer, in which the current urge to void was expressed as grip force, demonstrated that the intensity of sensations could be influenced voluntarily. We also examined brain activity during repetitive (1 Hz) contractions of pelvic floor muscles after the bladder was emptied. RESULTS: Significant brain activity associated with an increased urge to void was found in the insular cortex, frontal opercula, supplementary motor area (SMA), cingulate motor area (CMA), right posterior parietal cortex, left prefrontal cortex and cerebellum. Trends toward activation were detected in the thalamus, peri-aquaeductal gray matter and ventral pons. Suppression of the urge to void significantly activated the left superior frontal lobe. The SMA and CMA were active during voluntary rhythmical contractions of pelvic floor muscles. CONCLUSIONS: Sensation intensity of the desire to void can be influenced intentionally. Frontoparietal cortical areas and the SMA/CMA seem to be involved in this process.

Penile carcinoma (pT1 G2): surveillance or inguinal lymph node dissection?

BACKGROUND: Due to the low incidence of squamous cell penile cancer and lack of well-designed studies, controversies persist over the therapeutic approach in patients with pT1 G2 carcinoma. PATIENTS AND METHODS: Between 1992 and 2003, 16 patients with T1 squamous penile cancer were treated in our institution either by surveillance or by inguinal lymph node dissection (ILND). RESULTS: A total of 8 primary lesions were classified as pT1 G2 carcinoma with 4 tumors developing early or delayed inguinal metastatic disease. CONCLUSIONS: The natural behavior of pT1 G2 squamous penile carcinoma and its metastatic potential has been underestimated in recent literature. Since morbidity after early ILND has markedly decreased and its superiority over delayed ILND has been shown, we advocate the early modified inguinal lymph node dissection until strong prognostic factors for positive inguinal lymph nodes have been validated.

Methylene blue staining for nerve-sparing operative procedures: an animal model.

OBJECTIVES: To evaluate methylene blue fiber staining as a method of nerve fiber identification in an animal model, because the maintenance of organ function after surgery depends on exact intraoperative identification of the relevant nerve fibers. METHODS: Brindley electrodes were implanted bilaterally at S3 for sacral anterior root stimulation in six minipigs. For reference, stimulation-induced detrusor contractions were recorded urodynamically. After exposure of the ureterovesical junction on both sides, a 2:8 methylene blue solution was applied to the right side; the left side remained untreated. Bilateral dissection of the ureter from the surrounding tissue for a distance of 4 cm proximal to the ureterovesical junction was performed. The methylene blue-stained nerve fibers on the right side were spared; no particular attention was paid to the nerves on the left. Again, sacral anterior root stimulation-induced detrusor contractions were monitored urodynamically on both sides. Then, the identified nerve fibers on the right were cut intentionally, and the detrusor pressure was recorded again under stimulation. Finally, the dissected nerve structures were evaluated histologically. RESULTS: The reference bladder pressures after unilateral stimulation on the left side before ureter dissection showed a mean detrusor pressure (Pdet) of 19 cm H2O. On the right side, the Pdet was 18 cm H2O. After preparation on both sides, a mean Pdet of 3 cm H2O was recorded after left side stimulation, and a Pdet of 17 cm H2O after right side stimulation. When the stained nerve fibers on the right side were cut, no bladder contractions could be induced. The histomorphology of the stained and dissected structures revealed multiple autonomous nerve fibers and small vessels in connective tissue. CONCLUSIONS: The identification of minute nerve bundles is a tedious and difficult task. The results from our animal model demonstrated that supravital staining of autonomous nerve fibers with methylene blue is a simple and reliable method of identification.