Histological Study of the Cavernous Nerve Mesh Outside the Periprostatic Region: Anatomical Basis for Erectile Function after Nonnerve Sparing Radical Prostatectomy

The differences in the anatomy of the thoracolumbar and sacral autonomic outflow are quantitative

PURPOSE

We have re-evaluated the anatomical arguments that underlie the division of the spinal visceral outflow into sympathetic and parasympathetic divisions.

METHODOLOGY

Using a systematic literature search, we mapped the location of catecholaminergic neurons throughout the mammalian peripheral nervous system. Subsequently, a narrative method was employed to characterize segment-dependent differences in the location of preganglionic cell bodies and the composition of white and gray rami communicantes.

RESULTS AND CONCLUSION

One hundred seventy studies were included in the systematic review, providing information on 389 anatomical structures. Catecholaminergic nerve fibers are present in most spinal and all cranial nerves and ganglia, including those that are known for their parasympathetic function. Along the entire spinal autonomic outflow pathways, proximal and distal catecholaminergic cell bodies are common in the head, thoracic, and abdominal and pelvic region, which invalidates the "short-versus-long preganglionic neuron" argument. Contrary to the classically confined outflow levels T1-L2 and S2-S4, preganglionic neurons have been found in the resulting lumbar gap. Preganglionic cell bodies that are located in the intermediolateral zone of the thoracolumbar spinal cord gradually nest more ventrally within the ventral motor nuclei at the lumbar and sacral levels, and their fibers bypass the white ramus communicans and sympathetic trunk to emerge directly from the spinal roots. Bypassing the sympathetic trunk, therefore, is not exclusive for the sacral outflow. We conclude that the autonomic outflow displays a conserved architecture along the entire spinal axis, and that the perceived differences in the anatomy of the autonomic thoracolumbar and sacral outflow are quantitative.

Long-term efficacy of penile rehabilitation with low-intensity extracorporeal shock wave therapy for sexual and erectile function recovery following robotic-assisted radical prostatectomy: a single-cohort pilot study

Background

The long-term efficacy of low-intensity extracorporeal shock wave therapy (LIESWT) for penile rehabilitation after robot-assisted radical prostatectomy (RARP) has not yet been reported.

Aim

To assess the long-term efficacy of LIESWT for penile rehabilitation after RARP by evaluating the postoperative recovery of sexual and erectile functions following RARP.

Methods

Patients who underwent RARP at our institution were categorized into 2 groups: those who received LIESWT and those who underwent penile rehabilitation with a phosphodiesterase type 5 inhibitor (PDE5i). The control group included patients who did not undergo penile rehabilitation. Potency and scores on the Expanded Prostate Cancer Index Composite for sexual function and 5-item International Index of Erectile Function (IIEF-5) were evaluated preoperatively and over 60 months after RARP.

Outcomes

The LIESWT group had significantly higher postoperative sexual function and total IIEF-5 scores and potency than the control group over the long term, and its results were not inferior to those of the PDE5i group.

Results

The LIESWT, PDE5i, and control groups comprised 16, 13, and 139 patients, respectively. As compared with the control group, the LIESWT group had significantly higher sexual function scores at 6, 12, and 60 months after surgery (P < .05) and total IIEF-5 scores at 24 and 60 months (P < .05). The LIESWT group also had a significantly higher potency rate than the control group at 60 months (P < .05). For all time points after surgery, there were no significant differences between the LIESWT and PDE5i groups in terms of sexual function and total IIEF-5 scores and potency.

Clinical Implications

LIESWT may be a new option for penile rehabilitation in patients with erectile dysfunction after RARP.

Strengths and Limitations

This pilot study was performed at a single center and involved relatively few patients, which may have led to selection bias. Furthermore, the selection of this study for penile rehabilitation was not made randomly but by the patient's choice. Despite these limitations, our results provide evidence in support of LIESWT for penile rehabilitation after RARP because this is the first study to assess the long-term efficacy of LIESWT.

Conclusion

LIESWT can improve sexual and erectile functions in patients with erectile dysfunction after RARP, and its efficacy can be maintained over a long period after surgery.

The effects of primary realignment or suprapubic cystostomy on prostatic displacement in patients with pelvic fracture urethral injury: a clinical study based on MR urethrography

BACKGROUND

To provide direct evidence of whether primary realignment (PR) or suprapubic cystostomy (SPC) had different effects on the prostatic displacement and prognosis in patients with pelvic fracture urethral injury who needed delay anastomotic urethroplasty based on Magnetic Resonance (MR) urethrography.

METHODS

We screened the urethral stenosis database of our single institution from January 2016 to June 2020. Patients who underwent delayed anastomotic urethroplasty with a preoperative MR urethrography and no treatment history of urethra were included. We compared the urethral gap length and prostatic displacement between the PR and SPC group based on MR urethrography. The terminal outcomes such as stenosis-free rate, urinary continence and erectile function were also analyzed between two groups.

RESULTS

66 patients were included in this retrospective study in which 36 were in PR group and 30 in SPC group. Mean follow-up time was 15.1 months (3-38 months). One and two patients experienced recurrence of stenosis after urethroplasty in two groups (p = 1.000). No difference of erectile dysfunction and urinary incontinence was found between two groups. Based on MR urethrography, the urethral gap length was 17.4 mm and 23.3 mm (p = 0.008) which presented a significant decrease in PR group. The superior prostatic displacement was similar in two groups (9.8 mm vs. 13.8 mm, p = 0.081). The numbers and distance of displacement on lateral aspect showed no difference, either. However, PR group had less anterior-posterior prostatic displacement (p = 0.005). Besides, the erectile function was significantly related to the lateral prostatic displacement (p = 0.030/0.047).

CONCLUSIONS

Based on MR urethrography, patients in PR group showed shorter urethral gap distance and slighter anterior-posterior prostatic displacement without extra erectile dysfunction or incontinence. Besides, patients' erectile function might be significantly related to the lateral prostatic displacement.

Multi-Institutional Study of Dorsal Onlay Urethroplasty of the Membranous Urethra after Endoscopic Prostate Procedures: Operative Results, Continence, Erectile Function and Patient Reported Outcomes

(1) Background: To critically evaluate dorsal onlay buccal mucosal graft urethroplasty (DOBMGU) for posterior urethral stenosis repair following transurethral resection and other endoscopic prostate procedures. (2) Methods: A retrospective multi-institutional review of patients with membranous or bulbomembranous urethral stenosis for whom treatment with DOBMGU was conducted after receipt of prostate endoscopic procedures. Baseline data, peri-operative care, post-operative care and patient-reported outcomes were analyzed. The primary outcomes were procedural failure and development of de novo stress urinary incontinence (SUI). The secondary outcomes were changes in voiding, sexual function and patient satisfaction. (3) Results: A total of 107 men with a mean age of 69 ± 9.5 years and stenosis length of 3.5 ± 1.8 cm were included. Prior endoscopic procedures among participants were 47 patients (44%) with monopolar TURP, 33 (30.8%) with bipolar TURP, 16 (15%) with Greenlight laser, 9 (8.4%) with Holmium laser enucleation and 2 (1.9%) with bladder neck incision. At a mean follow-up time of 59.3 ± 45.1 months, stenosis recurred in 10 patients (9.35%). Multivariate analysis confirmed that postoperative complications (OR 12.5; p = 0.009), history of radiation (OR 8.3; p = 0.016) and ≥2 dilatations before urethroplasty (OR 8.3; p = 0.032) were independent predictors of recurrence. Only one patient (0.9%) developed de novo SUI. Patients experienced significant improvement in PVR (128 to 60 cc; p = 0.001), Uroflow (6.2 to 16.8 cc/s; p = 0.001), SHIM (11.5 to 11.7; p = 0.028), IPSS (20 to 7.7; p < 0.001) and QoL (4.4 to 1.7; p < 0.001), and 87 cases (81.3%) reported a GRA of + 2 or better. (4) Conclusions: DOBMGU is an effective and safe option for patients with posterior urethral stenosis following TURP and other prostate endoscopic procedures. This non-transecting approach minimizes external urinary sphincter manipulation, thus limiting postoperative risk of SUI or erectile dysfunction.

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

Background

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

Methods

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

Results

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

Conclusions

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

Reconstruction of Membranous Urethral Strictures

PURPOSE OF REVIEW

Due to the proximity of the rhabdosphincter and cavernous nerves to the membranous urethra, reconstruction of membranous urethral stricture implies a risk of urinary incontinence and erectile dysfunction. To avoid these complications, endoscopic management of membranous urethral strictures is traditionally favored, and bulboprostatic anastomosis is reserved as the main classical approach for open reconstruction of recalcitrant membranous urethral stricture. The preference for the anastomotic urethroplasty among reconstructive urologists is likely influenced by the familiarity and experience with trauma-related injuries. We review the literature focusing on the anatomy of membranous urethra and on the evolution of treatments for membranous urethral strictures.

RECENT FINDINGS

Non-traumatic strictures affecting bulbomembranous urethra are typically sequelae of instrumentation, transurethral resection of the prostate, prostate cancer treatment, and pelvic irradiation. Being a different entity from trauma-related injuries where urethra is not in continuity, a new understanding of membranous urethral anatomy is necessary for the development of novel reconstruction techniques. Although efficacious and durable to achieve urethral patency, classical bulboprostatic anastomosis carries a risk of de-novo incontinence and impotence. Newer and relatively less invasive reconstructive alternatives include bulbar vessel-sparing intra-sphincteric bulboprostatic anastomosis and buccal mucosa graft augmented membranous urethroplasty techniques. The accumulated experience with these techniques is relatively scarce, but several published series present promising results. These approaches are especially indicated in patients with previous transurethral resection of the prostate in which sparing of rhabdosphincter and the cavernous nerves is important in attempt to preserve continence and potency. Additionally, introduction of buccal mucosa onlay grafts could be especially beneficial in radiation-induced strictures to avoid transection of the sphincter in continent patients, and to preserve the blood supply to the urethra for incontinent patients who will require artificial urinary sphincter placement. The evidence regarding erectile functional outcomes is less solid and this item should be furtherly investigated.

nNOS-positive minor-branches of the dorsal penile nerves is associated with erectile function in the bilateral cavernous injury model of rats

The changes in neuronal nitric oxide synthases (nNOS) in the dorsal penile nerves (DPNs) are consistent with cavernous nerve (CN) injury in rat models. However, the anatomical relationship and morphological changes between the minor branches of the DPNs and the CNs after injury have never been clearly explored. There were forty 12 week old male Sprague-Dawley rats receiving bilateral cavernous nerve injury (BCNI). Erectile function of intracavernous pressure and mean arterial pressure were measured. The histology and ultrastructure with H&E stain, Masson's trichrome stain and immunohistochemical stains were applied on the examination of CNs and DPNs. We demonstrated communicating nerve branches between the DPNs and the CNs in rats. The greatest damage and lowest erectile function were seen in the 14^th day and partially recovered in the 28^th day after BCNI. The nNOS positive DPN minor branches' number was significantly correlated with erectile function. The sub-analysis of the number of nNOS positive DPN minor branches also matched with the time course of the erectile function after BCNI. We suggest the regeneration of the DPNs minor branches would ameliorate the erectile function in BCNI rats.

Midline sensory nerve supply to the anoscrotal junction: a study using human male fetuses

The origin of the posterior scrotal nerve is considered to be the bilateral pudendal nerves but the course to the midline is still obscure. Using 5 late-stage human male fetuses, we identified the single nerve through the intramuscular midline septum of the bulbospongiosus and the bilateral nerves along the left and right sides of the septum. Thus, the posterior scrotal nerve showed a variation: a single midline trunk or bilateral nerves. Branches of the bilateral pudendal nerves ran medially between the muscle and Cowper's gland and, at the midline area, they joined or associated closely. During the proximal course, much or less, the nerve penetrated the superior part of the muscle. The nerve entered the subcutaneous tissue at and near the perineal raphe. The communication with intrapelvic autonomic nerves were suggested behind Cowper's gland. Notably, the midline skin immediately anterior to the anus carried a considerable dense supply of thin sensory nerves. However, these nerves seemed to come from a space between the rectal smooth muscle and the external anal sphincter, not from the posterior scrotal nerve. Therefore, surgical treatment of the intersphincteric layer was likely to injure the original sensory nerve supply to the anterior anal skin.

Dorsal Onlay Urethroplasty for Membranous Urethral Strictures: Urinary and Erectile Functional Outcomes

PURPOSE

We evaluated urinary and erectile functional outcomes after dorsal onlay urethroplasty for bulbomembranous urethral strictures. Our aim was to understand the functional implications of dissection of the posterior urethra.

MATERIALS AND METHODS

We report on men who underwent membranous urethral stricture repair by buccal mucosal graft dorsal onlay substitution urethroplasty. Continence and erectile function were assessed preoperatively and postoperatively. Tissue routinely excised from the intercrural space during dissection of the dorsal aspect of the membranous urethra was evaluated for scar, striated muscle and nerves.

RESULTS

A total of 16 consecutive men with a mean age of 48.3 years (range 26 to 72) who had strictures with a mean length of 56 mm (range 15 to 170) involving the membranous urethra were included in analysis. Of the 16 men 15 were continent preoperatively and remained continent postoperatively. Three of 10 men (30%) with a preoperative SHIM (Sexual Health Inventory for Men) score of 17 to 25 had a decrease after urethroplasty. All 16 men had an improved maximum urinary flow rate with a mean improvement of 22 ml per second. I-PSS (International Prostate Symptom Score) improved from a median of 23 to 4 postoperatively with a median bother score improvement of 5 to 0. Histopathological assessment identified striated muscle and nerves in 6 (46%) and 9 (69%) of 13 specimens. Overall nerves and muscle comprised an average of less than 15% of the specimen.

CONCLUSIONS

The dorsal onlay technique with a buccal mucosal graft for membranous urethral stricture repair does not compromise continence or erectile function in most patients. Dissection at the level of the membranous urethra should be limited because striated muscle and cavernous nerves are present.

Bladder Neck Muscle Degeneration in Patients with Prostatic Hyperplasia

PURPOSE

To improve understanding of the variations of bladder neck musculature we investigated histological changes of the bladder neck associated with prostatic hyperplasia in adult male cadavers.

MATERIALS AND METHODS

We examined histological sections from 24 donated male cadavers with a mean age of 74 years. Sections were subjected to Azan and immunohistochemical staining using desmin and S-100 antibodies. The collagen content per cross-sectional area was calculated and statistically compared.

RESULTS

The existence of 3 muscle layers (submucosal longitudinal muscles, circular bladder neck muscles and external longitudinal muscles) was confirmed at the anterior and posterior regions of the bladder neck. Increased prostate volume significantly correlated with an increase in collagen fibers and thinning of muscle bundles in the anterior bladder neck. An increase in prostate volume and increasing age significantly correlated with degeneration of the posterior bladder neck muscles. As prostatic hyperplasia advanced the bladder neck muscles were progressively affected by fibrosis with the circular muscle fibers becoming thin and fragmented. In addition the severity of fibrosis associated with prostatic hyperplasia showed interindividual variation. We also devised a schematic classification of bladder neck morphology in men.

CONCLUSIONS

Degeneration of muscle bundles in the bladder neck of men with prostatic hyperplasia was confirmed. It was found that the bundles became thinner along with an increase in collagenous tissue. Our schematic classification of bladder neck morphology in men may be useful for further investigations.

Nerve-sparing Surgery Technique, Not the Preservation of the Neurovascular Bundles, Leads to Improved Long-term Continence Rates After Radical Prostatectomy

BACKGROUND

The effect of preservation of neurovascular bundles (NVBs) during radical prostatectomy (RP) on continence remains controversial.

OBJECTIVE

To analyze if the differing surgical techniques of nerve-sparing (NS) versus non-nerve-sparing (NNS) RP and not the preservation of the NVB itself may be responsible for differences in continence rates.

DESIGN, SETTING, AND PARTICIPANTS

A total of 18 427 men who underwent RP from 2002 to 2014 in a single high-volume center were analyzed retrospectively. Patients with bilateral NS RP, with primary NNS RP, and with bilateral secondary resection of the NVBs for positive frozen-section results after an initial bilateral nerve sparing (secNNS) RP were studied.

INTERVENTION

NS, NNS, or secNNS RP.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Multivariable and propensity score matched analyses adjusting for age, prostate volume, and year of surgery were performed to assess differences in continence rates after RP. Continence was defined as the use of no or one safety pad per day.

RESULTS AND LIMITATIONS

Post-RP urinary continence rates at 1 wk, 3 mo, and 12 mo were 59.8%, 76.2%, 85.4% in the NS group, 39.5%, 59.5%, and 87.0% in the secNNS group, and 29.1%, 52.8%, and 70.5% in the NNS group. Continence rates at 12 mo after surgery did not differ significantly between patients who had bilateral NS and patients who had resection of both NVBs after an initial nerve-sparing technique (secNNS). In contrast, when comparing the NNS study groups with initial NNS versus secNNS, the latter group had significantly higher continence rates after 12 mo.

CONCLUSIONS

Our results indicate that the meticulous apical dissection associated with the NS RP technique rather than the preservation of the NVBs itself may have a positive impact on long-term urinary continence rates.

PATIENT SUMMARY

We looked at continence rates after nerve-sparing (NS) versus non-NS radical prostatectomy (RP). NS surgery technique but not the preservation of the neurovascular bundles led to improved long-term continence rates after RP.