Impairment of accessory nerves around major pelvic ganglion leading to overflow urinary incontinence in rats.

AIMS: To investigate the relationship between lower urinary tract function and the accessory nerve (ACN) arising from the major pelvic ganglion (MPG). METHODS: Ten-week-old male Wistar/ST rats were randomly divided into eight groups according to the type of treatment (sham or bilateral accessory nerve injury [BACNI]) and the duration of observation (3 days, 1 week, 2 weeks, or 4 weeks: Sham-3d, Sham-1w, Sham-2w, Sham-4w, BACNI-3d, BACNI-1w, BACNI-2ws, and BACNI-4w. BACNI was induced in the following manner: the ACN was crushed for 1 min (2 mm away from the MPG) using reverse-action tweezers. The same procedure was performed on both sides. On the last day of each observation period, the bladder function was measured by awake cystometry, and histological evaluation was performed. RESULTS: All rats in the Sham groups micturated normally. In the BACNI-3d and BACNI-1w groups, all rats showed symptoms of overflow urinary incontinence (OUI). This OUI improved gradually over time. The bladder's size in the BACNI group was significantly larger than that in the Sham group (p < .01). In addition, fibrosis was observed in the subserosa of the bladder of rats in BACNI groups. CONCLUSION: The BACNI model rats exhibited OUI, suggesting that ACN is involved in the lower urinary tract function. It might be possible that ACN controls the function of either the bladder, the urethra, or both.

Superior Hypogastric Plexus and Its Surgical Implications During Spine Surgery: A Review.

The superior hypogastric plexus (SHP) is a complex nervous collection located at the lumbosacral region below the level of the aortic bifurcation. As a part of the autonomic nervous system, it is an extension of the preaortic plexuses and continues bilaterally as the hypogastric nerves that ultimately contribute to the inferior hypogastric plexus. Although commonly described as a plexiform structure, several morphologic variations exist. Damage to the SHP can occur during anterior and anterolateral approaches to the lumbosacral spine leading to dysfunction of the abdominopelvic viscera. Visceral afferents travel in the SHP and are responsible for transmitting pain. Management therapies such as SHP blockade or presacral neurectomy can reduce pelvic pain caused by cancer and nonmalignant etiologies. This review highlights some of the recent findings regarding the nature of the SHP.

Bazo errante / Wandering spleen

No disponible

Stimulation of the pelvic nerve increases bladder capacity in the prostaglandin E2 rat model of overactive bladder.

Overactive bladder (OAB) syndrome is a highly prevalent condition that may lead to medical complications and decreased quality of life. Emerging therapies focusing on selective electrical stimulation of peripheral nerves associated with lower urinary tract function may provide improved efficacy and reduced side effects compared with sacral neuromodulation for the treatment of OAB symptoms. Prior studies investigating the effects of pelvic nerve (PelN) stimulation on lower urinary tract function were focused on promoting bladder contractions, and it is unclear whether selective stimulation of the PelN would be beneficial for the treatment of OAB. Therefore our motivation was to test the hypothesis that PelN stimulation would increase bladder capacity in the prostaglandin E2 (PGE2) rat model of OAB. Cystometry experiments were conducted in 17 urethane-anesthetized female Sprague-Dawley rats. The effects of intravesical PGE2 vs. vehicle and PelN stimulation after intravesical PGE2 on cystometric parameters were quantified. Intravesical infusion of PGE2 resulted in decreased bladder capacity and increased voiding efficiency without a change in bladder contraction area under the curve, maximum contraction pressure, or contraction duration. Bladder capacity was also significantly decreased compared with vehicle (1% ethanol in saline) confirming that the change in bladder capacity was mediated by PGE2 PelN stimulation reversed the PGE2-induced change in bladder capacity and increased the external urethral sphincter electromyogram activity at a specific stimulation condition (amplitude of 1.0 times threshold at 10 Hz). These results confirm that the urodynamic changes reported in conscious rats are also observed under urethane anesthesia and that PelN stimulation is a novel and promising approach for the treatment of the symptoms of OAB.

The effects of neuromodulation in a novel obese-prone rat model of detrusor underactivity.

Obesity is a global epidemic associated with an increased risk for lower urinary tract dysfunction. Inefficient voiding and urinary retention may arise in late-stage obesity when the expulsive force of the detrusor smooth muscle cannot overcome outlet resistance. Detrusor underactivity (DUA) and impaired contractility may contribute to the pathogenesis of nonobstructive urinary retention. We used cystometry and electrical stimulation of peripheral nerves (pudendal and pelvic nerves) to characterize and improve bladder function in urethane-anesthetized obese-prone (OP) and obese-resistant (OR) rats following diet-induced obesity (DIO). OP rats exhibited urinary retention and impaired detrusor contractility following DIO, reflected as increased volume threshold, decreased peak micturition pressure, and decreased voiding efficiency (VE) compared with OR rats. Electrical stimulation of the sensory branch of the pudendal nerve did not increase VE, whereas patterned bursting stimulation of the motor branch of the pudendal nerve increased VE twofold in OP rats. OP rats required increased amplitude of electrical stimulation of the pelvic nerve to elicit bladder contractions, and maximum evoked bladder contraction amplitudes were decreased relative to OR rats. Collectively, these studies characterize a novel animal model of DUA that can be used to determine pathophysiology and suggest that neuromodulation is a potential management option for DUA.

Current concepts and practical techniques of nerve-sparing laparoscopic radical hysterectomy.

Laparoscopic radical hysterectomy has been widely performed for patients with early-stage cervical cancer. The operative techniques for nerve-sparing to avoid bladder dysfunction have been established during the past three decades in abdominal radical hysterectomy, but how these techniques can be applied to laparoscopic surgery has not been fully discussed. Prolonged operation time or decreased radicality due to less accessibility via a limited number of trocars may be a disadvantage of the laparoscopic approach, but the magnified visual field in laparoscopy may enable fine manipulation, especially for preserving autonomic nerve tracts. The present review article introduces the practical techniques for sparing bladder branches of pelvic nerves in laparoscopic radical hysterectomy based on understanding of the pelvic anatomy, clearly focusing on the differences from the techniques in abdominal hysterectomy.

Possible role of the major pelvic ganglion in the modulation of non-voiding activity in rats.

AIMS: The existence of a motor-sensory system contributing to bladder sensation is now becoming widely accepted. Although it is clear that the motor component of this system appears to be generated within the bladder wall, recent observations suggest that the mechanisms involved in its modulation may lie outside the wall. The present study was undertaken to gain more insights into the peripheral modulation of non-voiding activity and the role of the major pelvic ganglion. METHODS: Male Sprague-Dawley rats anesthetized with urethane were used. The bladder was filled till 60% of the micturition threshold volume. The baseline pressure and the superimposed non-voiding activity were observed before and after consecutive bilateral transections of the hypogastric and pelvic nerves and bilateral ablation of the major pelvic ganglia. RESULTS: Hypogastric and pelvic nerve transection didn't significantly change the baseline pressure and superimposed non-voiding activity. Removal of the major pelvic ganglia resulted into an increased baseline pressure when compared with the control and increased amplitude of the non-voiding contractions when compared with both the decentralized condition (both hypogastric and pelvic nerves transected) and the control. The frequency of the non-voiding contractions wasn't affected. CONCLUSIONS: Non-voiding activity during the urine storage phase seems to be modulated at the level of the major pelvic ganglion. This suggests the possibility of local circuits between the bladder and the peripheral ganglia that may be responsible for an inhibitory component influencing non-voiding activity.

Sympathetic ß-adrenergic mechanism in pudendal inhibition of nociceptive and non-nociceptive reflex bladder activity.

This study investigated the role of the hypogastric nerve and ß-adrenergic mechanisms in the inhibition of nociceptive and non-nociceptive reflex bladder activity induced by pudendal nerve stimulation (PNS). In α-chloralose-anesthetized cats, non-nociceptive reflex bladder activity was induced by slowly infusing saline into the bladder, whereas nociceptive reflex bladder activity was induced by replacing saline with 0.25% acetic acid (AA) to irritate the bladder. PNS was applied at multiple threshold (T) intensities for inducing anal sphincter twitching. During saline infusion, PNS at 2T and 4T significantly (P < 0.01) increased bladder capacity to 184.7 ± 12.6% and 214.5 ± 10.4% of the control capacity. Propranolol (3 mg/kg iv) had no effect on PNS inhibition, but 3-[(2-methyl-4-thiazolyl)ethynyl]pyridine (MTEP; 1-3 mg/kg iv) significantly (P < 0.05) reduced the inhibition. During AA irritation, the control bladder capacity was significantly (P < 0.05) reduced to ∼22% of the saline control capacity. PNS at 2T and 4T significantly (P < 0.01) increased bladder capacity to 406.8 ± 47% and 415.8 ± 46% of the AA control capacity. Propranolol significantly (P < 0.05) reduced the bladder capacity to 276.3% ± 53.2% (at 2T PNS) and 266.5 ± 72.4% (at 4T PNS) of the AA control capacity, whereas MTEP (a metabotropic glutamate 5 receptor antagonist) removed the residual PNS inhibition. Bilateral transection of the hypogastric nerves produced an effect similar to that produced by propranolol. This study indicates that hypogastric nerves and a ß-adrenergic mechanism in the detrusor play an important role in PNS inhibition of nociceptive but not non-nociceptive reflex bladder activity. In addition to this peripheral mechanism, a central nervous system mechanism involving metabotropic glutamate 5 receptors also has a role in PNS inhibition.

Colokinetic effect of noradrenaline in the spinal defecation center: implication for motility disorders.

Chronic abdominal pain in irritable bowel syndrome (IBS) usually appears in combination with disturbed bowel habits, but the etiological relationship between these symptoms remains unclear. Noradrenaline is a major neurotransmitter controlling pain sensation in the spinal cord. To test the hypothesis that the descending noradrenergic pathway from the brain stem moderates gut motility, we examined effects of intrathecal application of noradrenaline to the spinal defecation center on colorectal motility. Colorectal intraluminal pressure and expelled volume were recorded in vivo in anesthetized rats. Intrathecal application of noradrenaline into the L6-S1 spinal cord, where the lumbosacral defecation center is located, caused propulsive contractions of the colorectum. Inactivation of spinal neurons by tetrodotoxin blocked the effect of noradrenaline. Pharmacological experiments showed that the effect of noradrenaline is mediated primarily by alpha-1 adrenoceptors. The enhancement of colorectal motility by intrathecal noradrenaline was abolished by severing of the pelvic nerves. Our results demonstrate that noradrenaline acting on sacral parasympathetic preganglionic neurons through alpha-1 adrenoceptors causes propulsive motility of the colorectum in rats. Considering that visceral pain activates the descending inhibitory pathways including noradrenergic neurons, our results provide a rational explanation of the concurrent appearance of chronic abdominal pain and colonic motility disorders in IBS patients.

Inferior hypogastric plexus blockade versus acupuncture for the management of idiopathic chronic pelvic pain: A randomized clinical trial.

BACKGROUND: To compare the clinical efficacies of inferior hypogastric plexus blockade and acupuncture in the management of idiopathic chronic pelvic pain (CPP). METHODS: The study included 117 patients with CPP. Group 1 included 62 patients who underwent inferior hypogastric plexus blockade and group 2 included 55 patients who underwent acupuncture. Pain level was assessed using a visual analogue scale (VAS) immediately and at 2, 6, and 12 weeks after treatment. RESULTS: The preprocedure VAS score was 7.6 ± 0.15 in group 1 and 7.7 ± 0.24 in group 2 (p > 0.05). Pelvic pain decreased significantly in both groups after treatment, with pretreatment and posttreatment scores of 7.6 ± 0.15 and 2.2 ± 0.88, respectively, in group 1 (p < 0.0001) and 7.7 ± 0.24 and 4.7 ± 0.11, respectively, in group 2 (p < 0.0001). However, the decrease in pain scores throughout the clinical follow-up was significantly more in group 1 than in group 2 (p< 0.0001). Complete disappearance of symptoms was achieved in 72.6% of patients in group 1 compared to 54.5% of patients in group 2 (p = 0.3737). Patients who did not benefit from the treatment were significantly more in group 2 than in group 1 (25.5% vs. 6.5%, p = 0.0294). No complications were reported in both groups. CONCLUSION: The study results showed that inferior hypogastric blockade had a 72.6% success rate and showed a significantly higher effect on reducing pain intensity in a short period of time in the management of CPP, compared to acupuncture.

Preservation of the neurovascular bundles is associated with improved time to continence after radical prostatectomy but not long-term continence rates: results of a systematic review and meta-analysis.

CONTEXT: The aetiology of urinary incontinence following radical prostatectomy (RP) is incompletely understood. In particular, it is unclear whether there is a relationship between neurovascular bundle (NVB) sparing and post-RP urinary continence. OBJECTIVE: To review systematically the association of NVB sparing in RP with postoperative urinary continence outcomes and synthesise the results in a meta-analysis. EVIDENCE ACQUISITION: This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement. PubMed, Medline, and Cochrane Central Register of Controlled Trials were searched (December 2013), yielding 3413 unique records. A total of 27 longitudinal cohort studies were selected for inclusion. Studies were evaluated using a predefined criteria adapted from the Cochrane Tool to Assess Risk of Bias in Cohort Studies. EVIDENCE SYNTHESIS: Data from 13 749 participants in 27 studies were synthesised in a meta-analysis. An assessment of the study methodology revealed a high risk of bias due to differences in baseline characteristics, outcome assessment, and the likely presence of unreported confounding factors such as meticulous apical dissection. Meta-analysis demonstrated that nerve sparing (NS) compared with non-nerve sparing (NNS) resulted in improved early urinary continence rates up to 6 mo postoperatively. Beyond this time, no significant difference was observed. This effect was seen most clearly for bilateral NS compared with NNS. A sensitivity analysis of prospective cohort studies revealed consistent results. CONCLUSIONS: This analysis demonstrates an association between NS and improved urinary continence outcomes up to 6 mo postoperatively. NS in men with poor preoperative erectile function should be considered in the context of oncologic risk stratification because it may improve time to continence recovery. The underlying cause of the relationship between NS and continence is unknown. It may represent preservation of the intrapelvic somatic nerves supplying the rhabdosphincter or the influence of other confounding factors. Future research should be directed towards improving understanding of the anatomy of urinary continence and the pathophysiology of post-RP incontinence. PATIENT SUMMARY: We found that avoiding damage to the nerves around the prostate improves urinary continence in the first 6 mo after surgery. After this time, there is no difference in continence between men who had these nerves removed and those who had them saved. This finding could be due to a true effect of saving these nerves or to a number of other factors affecting the research.

Continence and micturition: an anatomical basis.

Urinary incontinence remains an important clinical problem worldwide, having a significant socio-economic, psychological, and medical burden. Maintaining urinary continence and coordinating micturition are complex processes relying on interaction between somatic and visceral elements, moderated by learned behavior. Urinary viscera and pelvic floor must interact with higher centers to ensure a functionally competent system. This article aims to describe the relevant anatomy and neuronal pathways involved in the maintenance of urinary continence and micturition. Review of relevant literature focusing on pelvic floor and urinary sphincters anatomy, and neuroanatomy of urinary continence and micturition. Data obtained from both live and cadaveric human studies are included. The stretch during bladder filling is believed to cause release of urothelial chemical mediators, which in turn activates afferent nerves and myofibroblasts in the muscosal and submucosal layers respectively, thereby relaying sensation of bladder fullness. The internal urethral sphincter is continuous with detrusor muscle, but its arrangement is variable. The external urethral sphincter blends with fibers of levator ani muscle. Executive decisions about micturition in humans rely on a complex mechanism involving communication between several cerebral centers and primitive sacral spinal reflexes. The pudendal nerve is most commonly damaged in females at the level of sacrospinous ligament. We describe the pelvic anatomy and relevant neuroanatomy involved in maintaining urinary continence and during micturition, subsequently highlighting the anatomical basis of urinary incontinence. Comprehensive anatomical understanding is vital for appropriate medical and surgical management of affected patients, and helps guide development of future therapies.

Involvement of parasympathetic pelvic efferent pathway in psychological stress-induced defecation.

AIM: To investigate the role of the pelvic nerve pathway in stress-induced acceleration of colorectal transit and defecation in rats. METHODS: Surgical transection of rectal nerves (rectal branches of the pelvic nerve), vagotomy (Vag) or adrenalectomy (Adx) were performed bilaterally in rats. Number of fecal pellet output of these rats was measured during 1-h water avoidance stress (WAS). To evaluate the colonic transit, rats were given phenol red through the catheter indwelled in the proximal colon and subjected to WAS. After WAS session, entire colon and rectum were isolated and distribution of phenol red was measured. Distal colonic and rectal transit was evaluated using glass bead. Rats were inserted the glass bead into the distal colon and evacuation rate of the bead was measured. Neural activation was assessed by immunohistochemical staining of c-Fos and PGP9.5 in colonic whole-mount preparations of longitudinal muscle myenteric plexus (LMMP). RESULTS: In the sham-operated rats (sham op), WAS significantly increased defecation and accelerated colorectal transit with marked elevation of plasma corticosterone level. Compared with sham-operated rats, increase in the excretion of fecal pellets during WAS was significantly reduced by rectal nerve transection (RNT) (sham op: 6.9 ± 0.8 vs RNT: 4.3 ± 0.6, P < 0.05) or Vag (sham op: 6.4 ± 0.8 vs Vag: 3.7 ± 1.1, P < 0.05), although corticosterone level remained elevated. Adx-rats significantly increased the defecation despite the lower corticosterone level. Distribution pattern of phenol red showed RNT inhibited distal colonic and rectal transit accelerated by WAS, while Vag inhibited proximal colonic transit. Suppression of distal colonic and rectal transit by RNT was further confirmed by the bead evacuation rate (sham op: 80.0% vs RNT: 53.8%). WAS significantly increased the number of c-Fos-immunoreactive neural cells in the LMMP of the proximal and distal colon, whereas c-Fos expression was decreased by RNT in the distal colon (sham op: 9.0 ± 2.0 vs RNT: 4.4 ± 1.0, P < 0.05) and decreased by Vag in the proximal colon. CONCLUSION: Pelvic nerve conveys WAS stimuli from the brain to the distal colon, and directly activate the myenteric neurons, followed by the increase of its motility.

Total mesorectal excision--does the choice of dissection technique have an impact on pelvic autonomic nerve preservation?

BACKGROUND: The aim of this experimental study was to assess the quality of pelvic autonomic nerve preservation of different dissection techniques. MATERIAL AND METHODS: Twelve pigs underwent low anterior rectal resection (LARR) with scissors, ultracision, monopolar diathermy, and waterjet, each in three animals. Assessment of pelvic autonomic nerve preservation was carried out by stimulation of the pelvic splanchnic nerves under electromyography of the internal anal sphincter (IAS). Neurostimulation was performed bilaterally after posterior dissection, after complete mesorectal dissection, and after rectal resection. RESULTS: Stimulation resulted in significantly increased amplitudes of the time-based electromyographic signal of the IAS, confirming nerve preservation. The stimulation results after complete mesorectal dissection showed comparable median amplitude increases for dissection with scissors (10.34 µV (interquartile range [IQR], 5.58; 14.74)) and ultracision (9.79 µV (IQR, 7.63; 11.6)). Lower amplitude increases were observed for monopolar diathermy (4.47 µV (IQR, 2.52; 10.46)) and waterjet (0.61 µV (IQR, 0.07; 2.11)) (p = 0.038). All animals undergoing dissection with scissors, ultracision, and monopolar diathermy had bilateral positive results. Of three animals undergoing LARR with waterjet, one had bilateral positive results. Two had unilateral negative results, indicating incomplete nerve preservation. CONCLUSION: Scissors, ultracision, and monopolar diathermy might have comparable nerve-sparing potentials and differed from waterjet.

Whole genome microarray of the major pelvic ganglion after cavernous nerve injury: new insights into molecular profile changes after nerve injury.

UNLABELLED: What's known on the subject? and What does the study add? With the present study, we aimed to provide a global picture of the molecular processes that are activated by CN injury. The present study used genomic expression profiling to identify candidate genes that might be useful targets in the CN recovery process and, thus, the ultimate preservation of penile erection. Regeneration of the CN and axonal outgrowth clearly involve changes in multiple biochemical pathways that have never been investigated by microarray analysis. We analyzed global gene expression in the major pelvic ganglion at early stages (48 h and 14 days) after CN injury and focused on the detection of changes in genes related to nervous tissue repair and proliferation. The findings of the present study provide important insight into the molecular systems affected by CN injury and identify candidate genes that may be utilized for novel molecular-based therapies for the preservation and protection of the CN during RP. OBJECTIVES: To to examine the complexity of the many molecular systems involved in supporting cavernous nerve (CN) repair and regeneration in a rat model of bilateral crush injury utilizing a microarray analysis approach. Erectile dysfunction (ED) is a common clinical complication after prostate cancer treatment by radical prostatectomy, and recovery of erectile function can take as long as 2 years. There are gaps in our understanding of the autonomic pelvic innervation of the penis that still need to be addressed for the development of an adequate treatment strategy for post-prostatectomy ED. The molecular mechanisms of the intrinsic ability of CN to regenerate after an injury have not been elucidated. MATERIALS AND METHODS: We analyzed global gene expression in the major pelvic ganglion 48 h and 14 days after CN injury. Overall, a comparative analysis showed that 325 genes changed at the 48-h time point and 114 genes changed at 14 days. There were 60 changed genes in common with both time points. Using the Ingenuity Pathway Analysis® system (Ingenuity Systems, Inc., Redwood City, CA, USA), we were able to analyze the significantly changed genes that were unique and common to each time point by biological function. We focused on the detection of changes related to nervous tissue repair and proliferation, molecular networks of neurotrophic factors, stem cell regulation and synaptic transmission. RESULTS: There was strong evidence of the early mobilization of genes involved in repair and neuroprotection mechanisms (SERPINF1, IGF1, PLAU/PLAUR, ARG1). Genes related to nervous system development (ATF3 GJA1, PLAU, SERPINE1), nerve regeneration (SERPINE2, IGF1, ATF3, ARG1) and synaptic transmission (GJC1, GAL) were changed. Several genes related to proliferation as well as apoptosis (A2M, ATF3, C3, EGR4, FN1, GJA1, GAL) were also changed, possibly as part of a protective mechanism or the initiation of remodelling. CONCLUSIONS: The results obtained show that multiple biological processes are associated with injury and repair of the CN and provide a systematic genome-wide screen for neurotrophic and/or inhibitory pathways of nerve regeneration. These data identify the candidate genes that may be utilized in novel molecular-based therapies for the preservation and protection of the CN during radical prostatectomy.

Recruitment of intracavernously injected adipose-derived stem cells to the major pelvic ganglion improves erectile function in a rat model of cavernous nerve injury.

BACKGROUND: Intracavernous (IC) injection of stem cells has been shown to ameliorate cavernous-nerve (CN) injury-induced erectile dysfunction (ED). However, the mechanisms of action of adipose-derived stem cells (ADSC) remain unclear. OBJECTIVES: To investigate the mechanism of action and fate of IC injected ADSC in a rat model of CN crush injury. DESIGN, SETTING, AND PARTICIPANTS: Sprague-Dawley rats (n=110) were randomly divided into five groups. Thirty-five rats underwent sham surgery and IC injection of ADSC (n=25) or vehicle (n=10). Another 75 rats underwent bilateral CN crush injury and were treated with vehicle or ADSC injected either IC or in the dorsal penile perineural space. At 1, 3, 7 (n=5), and 28 d (n=10) postsurgery, penile tissues and major pelvic ganglia (MPG) were harvested for histology. ADSC were labeled with 5-ethynyl-2-deoxyuridine (EdU) before treatment. Rats in the 28-d groups were examined for erectile function prior to tissue harvest. MEASUREMENTS: IC pressure recording on CN electrostimulation, immunohistochemistry of the penis and the MPG, and number of EdU-positive (EdU+) cells in the injection site and the MPG. RESULTS AND LIMITATIONS: IC, but not perineural, injection of ADSC resulted in significantly improved erectile function. Significantly more EdU+ ADSC appeared in the MPG of animals with CN injury and IC injection of ADSC compared with those injected perineurally and those in the sham group. One day after crush injury, stromal cell-derived factor-1 (SDF-1) was upregulated in the MPG, providing an incentive for ADSC recruitment toward the MPG. Neuroregeneration was observed in the group that underwent IC injection of ADSC, and IC ADSC treatment had beneficial effects on the smooth muscle/collagen ratio in the corpus cavernosum. CONCLUSIONS: CN injury upregulates SDF-1 expression in the MPG and thereby attracts intracavernously injected ADSC. At the MPG, ADSC exert neuroregenerative effects on the cell bodies of injured nerves, resulting in enhanced erectile response.

Models for sensory neurons of dorsal root ganglia and stress urinary incontinence.

AIMS: To discuss (1) animal models for investigating bladder afferent pathways from the spinal cord to the brain and (2) animal models of stress urinary incontinence (SUI) with a special emphasis on functional and histopathological characteristics of each model. METHODS: Literature review of spinal mechanisms of bladder afferent pathways and animal models of SUI. RESULTS: Electrophysiological studies in the rat using pelvic nerve stimulation and recording of evoked potentials in the periaqueductal gray (PAG) prove to be a valuable tool to examine spinal mechanisms of bladder afferent pathways. Animal models of SUI in the rat include vaginal distention as simulated birth trauma, pudendal nerve crush or transection, urethral sphincter injury by electrocauterization, transabdominal urethrolysis, periurethral botulinum-A toxin injection, and pubo-urethral ligament transection. Functional and histopathological changes in the continence mechanism after injury are different between models. CONCLUSIONS: Using animal models for sensory neurons, intrathecal and intravenous administration of certain drugs can be tested whether they affect the bladder afferent pathways from the spinal cord to the PAG. Animal models of SUI can serve as a tool to develop new pharmacologic therapies or periurethral injection therapies using stem cell implants.

Anatomical tracer injections into the lower urinary tract may compromise cystometry and external urethral sphincter electromyography in female rats.

Physiological and anatomical investigations are commonly combined in experimental models. When studying the lower urinary tract (LUT), it is often of interest to perform both urodynamic studies and retrogradely labeled neurons innervating the peripheral target organs. However, it is not known whether the use of anatomical tracers for the labeling of, e.g. spinal cord neurons may interfere with the interpretation of the physiological studies on micturition reflexes. We performed cystometry and external urethral sphincter (EUS) electromyography (EMG) under urethane anesthesia in adult female rats at 5-7 days after injection of a 5% fluorogold (FG) solution or vehicle into the major pelvic ganglia (MPG) or the EUS. FG and vehicle injections into the MPG and EUS resulted in decreased voiding efficiency. MPG injections increased the duration of both bladder contractions and the inter-contractile intervals. EUS injections decreased EUS EMG bursting activity during voiding as well as increased both the duration of bladder contractions and the maximum intravesical pressure. In addition, the bladder weight and size were increased after either MPG or EUS injections in both the FG and vehicle groups. We conclude that the injection of anatomical tracers into the MPG and EUS may compromise the interpretation of subsequent urodynamic studies and suggest investigators to consider experimental designs, which allow for physiological assessments to precede the administration of anatomical tracers into the LUT.

Surgical management of the pelvic plexus and lower abdominal nerves.

OBJECTIVE: Nerves of the pelvic plexus and lower abdominal wall can lead to chronic neuralgias owing to a variety of causes, including iatrogenic injury, trauma, tumors, and primary nerve entrapment. Differentiating among the various neural etiologies can be a challenging task. Here, we present a large series of patients who underwent surgical treatment of these nerves, with an emphasis on diagnostic and therapeutic considerations. METHODS: Between 1970 and 2006, the senior authors (DGK and DHK) surgically treated 264 cases of neuralgia of the pelvic plexus and nerves. A retrospective analysis of the patients' history, physical, diagnostic examinations, and follow-up was performed. RESULTS: Twenty-five cases of solely ilioinguinal neuralgia and 24 cases of combined ilioinguinal neuralgias were treated. Of these, iatrogenic injury was the most common etiology. One hundred forty-five patients underwent surgical exploration for either femoral nerve injury (119 patients) or lateral femoral cutaneous compression (26 patients). Seventy-five percent of patients had femoral nerve injuries attributable to trauma (iatrogenic versus penetrating injuries), and the remaining 25% of patients had cystic masses or tumors. Fifty-two masses of the pelvic plexus were treated, including neurofibromas (68%), schwannomas (18%), malignant nerve sheath tumors (5%), and non-neural sheath tumors (9%). CONCLUSION: Effective surgical management of these complex neuralgias depends on a solid understanding of the surgical anatomy and proper diagnosis. Electromyography and local anesthetic blocks not only can provide insight into the diagnosis but also have predictive value in assessing which patients may benefit from neurectomy or neurolysis.