Pathophysiology: the varieties of bladder overactivity

Comparison of Pelvic Floor Muscle Training With Connective Tissue Massage to Pelvic Floor Muscle Training Alone in Women With Overactive Bladder: A Randomized Controlled Study

OBJECTIVE

The purpose of this study was to compare the effects of a 6-week program of pelvic floor muscle training (PFMT) plus connective tissue massage (CTM) to PFMT alone in women with overactive bladder (OAB) symptoms on those symptoms, pelvic floor muscle strength, and quality of life.

METHODS

Thirty-four participants were randomly divided into PFMT+CTM (n = 17) and PFMT (n = 17) groups. PFMT was applied every day and CTM was applied 3 days a week for 6 weeks. Before treatment, at week 3, and after treatment (week 6), we assessed pelvic floor muscle strength (with a perineometer), bladder symptoms (with a urine diary), OAB symptom severity (with the 8-item Overactive Bladder Questionnaire [OAB-V8]), urgency (with the Patient Perception of Intensity of Urgency Scale [PPIUS]), and quality of life (with King's Health Questionnaire [KHQ]). The Mann-Whitney U test, χ² test, Friedman test, and Dunn multiple comparison test were used for analysis.

RESULTS

In both groups, pelvic floor muscle strength increased, whereas OAB symptoms and PPIUS and KHQ scores decreased after treatment (P < .05). Although the OAB-V8, PPIUS, and KHQ scores decreased at week 3, frequency, OAB-V8, and PPIUS scores, in addition to some parameters of the KHQ, decreased after treatment in the PFMT+CTM group compared to the PFMT group (P < .05).

CONCLUSION

Compared to PFMT alone, PFMT+CTM achieved superior outcomes in reducing OAB symptoms in the early and late periods.

The risk factors for recurrence of febrile urinary tract infection and renal scarring in children with functional urinary incontinence

OBJECTIVES

Functional urinary incontinence is often associated with recurrent urinary tract infection (UTI), vesicoureteral reflux (VUR), and renal scarring. This study aims to evaluate the correlations between urodynamic findings and recurrence of UTI, VUR, and renal scarring in children with functional incontinence.

METHODS

In this retrospective observational study, data on the presence of VUR, urodynamics and 99Tc-dimercaptosuccinic acid scintigraphy findings, and episodes of febrile UTI were obtained from patients' records. The patients had at least 3 years of follow-up.

RESULTS

There were significant associations between recurrence of UTI and decreased bladder capacity (hazard ratio: 1.321, P = .028). The receiver operator characteristic curve analysis showed a cutoff value for compliance of 13.25 mL/cmH₂ O for renal scarring (P = .000). There was a significant association between bladder wall thickening and VUR (odds ratio: 2.311, P = .008). The compliance had a cutoff value of 14.7 mL/cm H₂ O (P = .023) for severe VUR. The frequency of renal scarring was higher in patients with severe VUR and dysfunctional voiding (P = .001 and P = .041, respectively). The independent risk factors for renal scarring were low compliance, severe VUR, and dysfunctional voiding in children with functional incontinence, but recurrence of febrile UTI was not a risk factor for renal scarring. Decreased bladder capacity was a risk factor for recurrence of febrile UTI.

CONCLUSIONS

The present study suggests that low compliance, severe VUR, and dysfunctional voiding, but not the recurrence of febrile UTI, are the independent risk factors for renal scarring in children with functional incontinence, and decreased bladder capacity is the risk factor for the recurrence of febrile UTI.

Increased expression of neuregulin 1 in the urothelium of rat bladder with partial bladder outlet obstruction

Background

This study determined whether changes in the expression of neuregulin (NRG) 1, erbB2 tyrosine kinase (ErbB2) and the M2 muscarinic receptor in the urothelium and detrusor muscle of the rat bladder were associated with partial bladder outlet obstruction (PBOO).

Methods

Male Sprague-Dawley rats (body weight 250–300 g) were used and subdivided into control (n = 10) and PBOO groups (n = 20). PBOO was induced for 21 days, and the expression of NRG1, ErbB2 and M2 muscarinic receptor mRNA and protein was evaluated using reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting, respectively.

Results

In the urothelium of rat bladder samples, protein expression and mRNA expression of NRG1, ErbB2 and M2 muscarinic receptor were significantly increased in the PBOO group compared to the control group (p < 0.05). Only mRNA expression levels of NRG1/ ErbB2 were higher in the detrusor muscle of the PBOO group compared to the control group (p < 0.05).

Conclusions

Our study demonstrated remarkable changes in the expression of NRG1/ErbB2 receptor mRNA and protein in the urothelium and muscle layer. These results suggest that NRG1 overexpression plays some kind of role against the PBOO-induced upregulated muscarinic receptors in detrusor overactivity.

Intravesical Sodium Chondroitin Sulphate to Treat Overactive Bladder: Preliminary Result

Purpose:

This study aimed to verify the efficacy and safety of intravesical treatment with sodium chondroitin sulfate (CS) in patients with overactive bladder (OAB) who are refractory to previous antimuscarinic treatment.

Methods:

This study was performed between June 2012 and January 2015 and included 31 consecutive women (mean age, 42.10±7.34 years) with OAB who had been previously treated with two types of antimuscarinic drugs. The results of gynecologic and cystoscopic examinations were normal, and OAB comorbidity was absent. Treatment with intravesical instillations containing 40 mL CS (0.2%; 2 mg/mL) was administered for 6 weeks; after weekly treatments, monthly treatments were administered. The OAB-validated 8 (OAB-V8) symptom scores, nocturia, frequency, urgency, urge incontinence, and urinary volumes measured by uroflowmetry were evaluated for all the patients. The values obtained before the treatment were statistically compared with those obtained six months after the treatment.

Results:

The duration of the symptoms was 18.36±6.19 months. A statistically significant improvement of the patients’ conditions was observed in terms of the OAB-V8 symptom scores, nocturia, frequency, urgency, urge incontinence, and urinary volumes measured by uroflowmetry after the treatment.

Conclusions:

Despite the limitations of this study, the outcomes confirmed that CS therapy is safe and effective for the treatment of OAB.

A survey on the management of overactive bladder by Indonesian urologists

Background: Overactive bladder (OAB) is a clinical syndrome consisting of symptom complex of urgency, with or without incontinence which has significant effects on quality of life and has to be managed properly. The aim of this study was to review the management of OAB by Indonesian urologists.Methods: A self-constructed questionnaires containing diagnostic and treatment options of OAB patients were distributed to Indonesian urologists. This was a cross-sectional study and descriptive analysis method was used to analyze the data.Results: 129 Indonesian urologists participated in this study. Most of them faced more than 20 OAB cases per year with the most common type was OAB without incontinence or dry OAB (57.4%). Most urologists (34.1%) ordered at least three diagnostic tools to determine OAB. They were bladder diary, urinalysis and scoring system. The most used scoring system (48.9%) was the overactive bladder symptoms score (OABSS). Thirty-five point seven percents (35.7%) of urologists used antimuscarinic and behavioral therapy as initial therapy. Solifenacin 5 mg/day was the most common antimuscarinic prescribed as the first line therapy (48%). Most common items commonly evaluated for follow-up: symptoms (96.9%), bladder diary (72.9%); and drug’s side effect (58.1%). When initial therapy had failed, most of the urologists (54.3%) chose to increase the dose of antimuscarinic. None of them chose bladder botulinum toxin injection as their additional therapy.Conclusion: OAB is a frequent disorder which remains a challenge for urologists. The management of patients with OAB by Indonesian urologists has been suitable with the previous studies and guidelines.

The Impact of Increased Bladder Blood Flow on Storage Symptoms after Holmium Laser Enucleation of the Prostate

In order to investigate how holmium laser enucleation of the prostate (HoLEP) improves urinary storage symptoms, we assessed blood flow in the urinary bladder mucosa of patients with benign prostatic hyperplasia (BPH) before and after laser surgery. Seventy-four consecutive patients with BPH (median age 69 years, range; 53–88) underwent HoLEP at our institution and are included in this study. We prospectively assessed the International Prostate Symptom Score (IPSS), IPSS-QOL Score, the Overactive Bladder Symptom Score (OABSS), uroflowmetry, and blood flow in the urinary bladder, before and after surgery. Blood flow in the bladder mucosa was measured using the OMEGA FLOW (OMEGAWAVE, Tokyo, Japan) laser Doppler flowmeter. The median volume of the enucleated adenomas was 45.0 g (range: 25.0 to 83.2). The median IPSS improved significantly from 20 (range: 6–35) to 3 (0–22) (p<0.001; Wilcoxon signed-rank test), as did the storage symptoms score, which decreased from 13 (2–20) to 3 (1–8) (p<0.001). Median bladder blood flow increased at the trigone from 9.57±0.83 ml/sec to 17.60±1.08 ml/sec. Multiple regression analysis for the improved storage symptom score eliminated all explanatory variables except increased bladder perfusion. The data suggest that HoLEP improves blood flow in the bladder mucosa, which independently leads to the improvement of storage symptoms.

A comprehensive non-clinical evaluation of the CNS penetration potential of antimuscarinic agents for the treatment of overactive bladder

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

This study provides antimuscarinic agents for overactive bladder (OAB) display variable association with side effects mediated by the central nervous system (CNS), which may be of particular concern in the elderly. Adverse effects on CNS functioning are related to muscarinic receptor subtype selectivity and the ability of the agent to cross the blood-brain barrier, where P-gp plays a role in limiting permeability.

WHAT THIS STUDY ADDS

This study provides a parallel investigation of CNS penetration of antimuscarinic OAB agents in vivo and assessment of physical properties and permeability in cell monolayers in vitro. It adds further understanding of the roles of passive transcellular permeability and P-gp in determining CNS penetration of antimuscarinic OAB agents. It also enables a comparison of CNS side-effect profiles of OAB agents with preclinical CNS penetration data.

AIMS

To assess and compare the mechanisms of central nervous system (CNS) penetration of antimuscarinic overactive bladder (OAB) agents.

METHODS

Physical properties were computed or compiled from the literature. Rats were administered 5-hydroxymethyl tolterodine (HMT), darifenacin, oxybutynin, solifenacin, tolterodine or trospium subcutaneously. At 1 h postdose, plasma, brain and cerebrospinal fluid (CSF) concentrations were determined using LC-MS/MS assays. Brain and plasma protein binding were determined in vitro. Permeability in the presence and absence of the efflux transporter P-glycoprotein (P-gp) was assessed in RRCK and MDCK-MDR1 transwell assays.

RESULTS

Oxybutynin displayed extensive CNS penetration, with brain:plasma ratios (B:P), unbound brain:unbound plasma ratios (Kp,free) and CSF:free plasma ratios each >1. Tolterodine (B:P = 2.95, Kp,free = 0.23 and CSF:free plasma = 0.16) and solifenacin (B:P = 3.04, Kp,free = 0.28 and CSF:free plasma = 1.41) showed significant CNS penetration but with some restriction from CNS as indicated by Kp,free values significantly <1. 5-HMT, darifenacin and trospium displayed much lower B:P (0.03-0.16), Kp,free (0.01-0.04) and CSF:free plasma (0.004-0.06), consistent with poor CNS penetration. Permeability in RRCK cells was low for trospium (0.63 × 10(-6) cm s(-1) ), moderate for 5-HMT (11.7 × 10(-6) cm s(-1) ) and high for darifenacin, solifenacin, tolterodine and oxybutynin (21.5-38.2 × 10(-6) cm s(-1) ). In MDCK-MDR1 cells 5-HMT, darifenacin and trospium, were P-gp substrates, whereas oxybutynin, solifenacin and tolterodine were not P-gp substrates.

CONCLUSIONS

Brain penetration was low for antimuscarinics that are P-gp substrates (5-HMT, darifenacin and trospium), and significant for those that are not P-gp substrates (oxybutynin, solifenacin and tolterodine). CNS adverse events reported in randomized controlled clinical trials show general alignment with the preclinical data described in this study.

Characterization of overactive bladder in women in a primary care setting

BACKGROUND

Overactive bladder (OAB) represents a disorder with overall increasing prevalence in the American population. However, gender-specific characteristics of OAB and how it relates to the general practitioner are not well described. We sought to determine the distribution and characteristics of OAB in women in a primary care setting.

METHODS

Self-administered questionnaires were distributed to patients visiting a family medicine outpatient center. The modified questionnaire included eight questions on evidence of lower urinary tract symptoms (LUTS, OAB-validated 8-question screener [OAB-V8]), two questions on stress urinary incontinence, and one question on incomplete emptying. The questionnaire included demographic characteristics and relevant medical and surgical history. Body mass index was calculated based on weight and height. Chi-square test and risk ratio analysis were used to analyze the relationship between OAB and other independent variables.

RESULTS

Of 1025 questionnaires administered, 386 were completed. Patients ranged from 16 to 97 years, the majority were African American (78.2%), and 49.7% were premenopausal while 50.3% were postmenopausal. OAB was present in 46.4% of premenopausal women and 41.7% of postmenopausal women. OAB was significantly associated with overweight status (body mass index 25.0-29.9, P = 0.042) and obesity (body mass index ≥30, P < 0.001). Overall, obese women were twice as likely to have OAB (relative risk = 1.99, 1.31-3.04) than women with normal weight. OAB was not shown to correlate with race, cigarette use, history of hysterectomy, or parity.

CONCLUSION

OAB was evident in 44% of all female patients surveyed, which is much higher than previously reported estimates. In addition, overweight women were more likely to have OAB. Increased awareness of OAB in the primary care setting should be considered for women's general health.

Role of TREK-1 potassium channel in bladder overactivity after partial bladder outlet obstruction in mouse

PURPOSE

Mouse models of partial bladder outlet obstruction cause bladder hypertrophy. Expression of a number of ion channels is altered in hypertrophic detrusor muscle, resulting in bladder dysfunction. We determined whether mechanosensitive TREK-1 channels are present in the murine bladder and whether their expression is altered in partial bladder outlet obstruction, resulting in abnormal filling responses.

MATERIALS AND METHODS

Partial bladder outlet obstruction was surgically induced in CD-1 mice and the mice recovered for 14 days. Cystometry was done to evaluate bladder pressure responses during filling at 25 microl per minute in partial bladder outlet obstruction mice and sham operated controls. TREK-1 channel expression was determined at the mRNA and protein levels by quantitative reverse transcriptase-polymerase chain reaction and Western blotting, respectively, and localized in the bladder wall using immunohistochemistry.

RESULTS

Obstructed bladders showed about a 2-fold increase in weight vs sham operated bladders. TREK-1 channel protein expression on Western blots from bladder smooth muscle strip homogenates was significantly decreased in obstructed mice. Immunohistochemistry revealed a significant decrease in TREK-1 channel immunoreactivity in detrusor smooth muscle in obstructed mice. On cystometry the TREK-1 channel blocker L-methioninol induced a significant increase in premature contractions during filling in sham operated mice. L-methioninol had no significant effect in obstructed mice, which showed an overactive detrusor phenotype.

CONCLUSIONS

TREK-1 channel down-regulation in detrusor myocytes is associated with bladder overactivity in a murine model of partial bladder outlet obstruction.

Prevalence, evaluation and management of overactive bladder in primary care

Background

Patients with overactive bladder (OAB) are under-diagnosed in the primary care setting. Primary care physicians (PCP) approach to the patient and appropriate patient disclosure may contribute to under-diagnosis.

Methods

An outpatient primary care setting was used to determine the prevalence and characteristics of OAB. Patients who visited the family medicine outpatient clinic were invited to answer a self-administered questionnaire. It included questions on evidence of lower urinary tract symptoms (modified Overactive Bladder-Validated 8-question Screener [OAB-V8]), relevant medical and surgical history, and demographic data. Relationship between OAB and other independent variables were analyzed using chi-square and risk ratio (RR) analysis.

Results

Of 325 questionnaires distributed, 311 were returned completed. Patients ranged from 18 to 97 years, the majority women (74.0%) and African American (74.3%). OAB was present in 60.5% of men and 48.3% of women (p = 0.058). OAB was significantly associated with obesity (BMI > = 30) in women (p = 0.018, RR = 1.72), specifically obese premenopausal women (age < 55 years) (p = 0.011, RR = 1.98).

Conclusion

OAB prevalence is more than double and higher in men than previously reported. The relative risk for OAB is significantly greater in obese premenopausal women.

Bladder control, urgency, and urge incontinence: evidence from functional brain imaging

AIM

To review brain imaging studies of bladder control in subjects with normal control and urge incontinence; to define a simple model of supraspinal bladder control; and to propose a neural correlate of urgency and possible origins of urge incontinence.

METHODS

Review of published reports of brain imaging relevant to urine storage, and secondary analyses of our own recent observations.

RESULTS

In a simple model of normal urine storage, bladder and urethral afferents received in the periaqueductal gray (PAG) are mapped in the insula, forming the basis of sensation; the anterior cingulate gyrus (ACG) provides monitoring and control; the prefrontal cortex makes voiding decisions. The net result, as the bladder fills, is inhibition of the pontine micturition center (PMC) and of voiding, together with gradual increase in insular response, corresponding to increasing desire to void. In urge-incontinent subjects, brain responses differ. At large bladder volumes and strong sensation, but without detrusor overactivity (DO), most cortical responses become exaggerated, especially in ACG. This may be both a learned reaction to previous incontinence episodes and the neural correlate of urgency. The neural signature of DO itself seems to be prefrontal deactivation. Possible causes of urge incontinence include dysfunction of prefrontal cortex or limbic system, suggested by weak responses and/or deactivation, as well as abnormal afferent signals or re-emergence of infantile reflexes.

CONCLUSIONS

Bladder control depends on an extensive network of brain regions. Dysfunction in various parts may contribute to urge incontinence, suggesting that there are different phenotypes requiring different treatments.

Risk factors for renal scarring in children and adolescents with lower urinary tract dysfunction

Risk factors for renal scarring in children with lower urinary tract dysfunction (LUTD) were evaluated. The medical records of 120 patients were assessed concerning gender, presence of vesicoureteric reflux (VUR), bladder capacity, detrusor overactivity, residual urine, febrile urinary tract infection (UTI), bacteriuria, constipation, detrusor sphincter incoordination (DSI), high detrusor pressure at maximal cystometric capacity (PMCC), low compliance, and thickness and trabeculation of the bladder wall. Renal scarring was diagnosed by (99m)technetium-dimercaptosuccinic acid renal scan (DMSA). Renal scarring was detected in 38 patients (31%). VUR, UTI, decreased bladder capacity, urinary residue, and trabeculated and thick bladder wall were associated with scarring at univariate analysis. Multivariate analysis showed VUR (P < 0.0001) as the independent risk factor for renal scarring. Thickness of the bladder wall was a marginal risk factor (P = 0.07). Although UTI was not a risk factor, it was associated with VUR (P = 0.03). In our analysis, VUR was the main risk factor; however, renal scarring was probably due to multifactorial causes, as VUR was associated with UTI.

Cerebral control of the bladder in normal and urge-incontinent women

AIM

To identify age-related changes in the normal brain/bladder control system, and differences between urge incontinence in younger and older women, as shown by brain responses to bladder filling; and to use age, bladder volume, urge incontinence and detrusor overactivity (DO) as probes to reveal control system function. Functional MRI was used to examine regional brain responses to bladder infusion in 21 females (26-85 years): 11 "cases" with urge incontinence and DO (proven previously) and 10 normal "controls". Responses and their age dependence were determined at small and large bladder volumes, in whole brain and in regions of interest representing right insula and anterior cingulate (ACG). In "controls", increasing bladder volume/sensation led to increasing insular responses; with increasing age, insular responses became weaker. In younger "cases", ACG responded abnormally strongly at large bladder volumes/strong sensation. Elderly "cases" showed strong ACG responses even at small bladder volume but more moderate responses at larger volumes; if DO occurred, pontine micturition center (PMC) activation did not increase.

CONCLUSION

Among normal "controls", increasing age leads to decreased responses in brain regions involved in bladder control, including right insula, consistent with its role in mapping normal bladder sensations. Strong ACG activation occurs in urge-incontinent "cases" and may be a sign of urgency, indicating recruitment of alternative pathways when loss of bladder control is feared. Easier ACG provocation in older "cases" reflects lack of physiological reserve or different etiology. ACG responses seem associated with PMC inhibition: reduced ACG activity accompanies failure of inhibition (DO).

Sacral neuromodulation as a functional treatment of bladder overactivity

Sacral neuromodulation, namely the electrical stimulation of the sacral nerves has become an alternative treatment for cases of idiopathic bladder overactivity. The mechanism of action in this type of spinal cord modulation is only partially understood but it seems to involve stimulation of inhibitory interneurons. Temporary sacral nerve stimulation is the first step. It consists of the temporary application of neurostimulation as a diagnostic test in order to check the integrity of the sacral root and determine the best location for the implant. If the test stimulation is successful, a permanent device is implanted. In experienced hands, this is a safe procedure. When the patients are selected on the basis of sound criteria, more than three-quarters of them show a clinically significant improvement with a reduction in the frequency of incontinence episodes by more than 50%; however, the results vary according to each author's method of evaluation. The application of this technique should be combined with careful follow-up and attentive adjustments of the stimulation parameters in order to optimize the coordination of activity between the neurological systems involved.

A mechanical model for adjustable passive stiffness in rabbit detrusor

Strips of rabbit detrusor smooth muscle (DSM) exhibit adjustable passive stiffness characterized by strain softening: a loss of stiffness on stretch to a new length distinct from viscoelastic behavior. At the molecular level, strain softening appears to be caused by cross-link breakage and is essentially irreversible when DSM is maintained under passive conditions (i.e., when cross bridges are not cycling to produce active force). However, on DSM activation, strain softening is reversible and likely due to cross-link reformation. Thus DSM displays adjustable passive stiffness that is dependent on the history of both muscle strain and activation. The present study provides empirical data showing that, in DSM, 1) passive isometric force relaxation includes a very slow component requiring hours to approach steady state, 2) the level of passive force maintained at steady state is less if the tissue has previously been strain softened, and 3) tissues subjected to a quick-release protocol exhibit a biphasic response consisting of passive force redevelopment followed by force relaxation. To explain these and previously identified characteristics, a mechanical model for adjustable passive stiffness is proposed based on the addition of a novel cross-linking element to a hybrid Kelvin/Voigt viscoelastic model.

Effectiveness and tolerability of extended-release oxybutynin vs extended-release tolterodine in women with or without prior anticholinergic treatment for overactive bladder

The efficacy and the tolerability of extended-release oxybutynin chloride, 10 mg daily, and extended-release tolterodine tartrate, 4 mg daily, in women with or without prior anticholinergic treatment for overactive bladder (OAB) were compared in a post-hoc analysis of data from the Overactive Bladder: Performance of Extended Release Agents (OPERA) trial. The patient population and study methods have been described previously (Diokno et al., for the OPERA Study Group, Mayo Clin Proc 78:687-695, 2003). Among the group with anticholinergic experience, extended-release oxybutynin was significantly more effective than extended-release tolterodine in reducing micturition frequency at last observation (p=0.052). Complete freedom from urge incontinence was reported by significantly more patients taking oxybutynin than tolterodine at last observation (23.6 vs 15.1%, p=0.038). In addition, among patients completing a full 12 weeks of oxybutynin treatment, significantly greater reductions were observed compared with those taking tolterodine on the primary efficacy variable, number of urge incontinence episodes (p=0.049), and the combined total of urge and non-urge episodes (p=0.012), although the differences between treatment groups were not significant at last observation. In the anticholinergic-naïve group, efficacy and tolerability outcomes were similar across treatments, except that oxybutynin was associated with a significantly lower frequency of micturition at last observation (p=0.035). No efficacy differences favoring tolterodine were observed, and tolerability of the treatments was comparable. Dry mouth (mostly mild to moderate in severity) was reported significantly more often among participants taking extended-release oxybutynin than extended-release tolterodine (32.2 vs 19.2%, p=0.004), but only among those with previous anticholinergic experience. Discontinuation rates were comparably low across groups. The results demonstrate the appropriateness of initiating treatment for OAB with extended-release oxybutynin, particularly in women presenting with incontinence.

Diagnosis and management of patients with overactive bladder syndrome and abnormal detrusor activity

Overactive bladder syndrome (OABS) is a widely recognized syndrome with symptoms that can include urinary urgency, frequency, nocturia, and incontinence. Although there may be several causative factors for OABS, detrusor overactivity is the most common. In addition, urinary incontinence can also be due to a distinct but equally bothersome condition underactive bladder syndrome, or detrusor underactivity. The incomplete bladder emptying that characterizes detrusor underactivity often arises from impaired contractile function of the detrusor muscle. The variations in etiologies of the two syndromes necessitate patient evaluations tailored to individual symptom presentation. Increased awareness of the differences between the manifestations of OABS and underactive bladder syndrome call for specific approaches to the management of bladder dysfunction.

A Shifted Paradigm for the Further Understanding, Evaluation, and Treatment of Lower Urinary Tract Symptoms in Men: Focus on the Bladder

Lower urinary tract symptoms (LUTS) are highly prevalent among older men and have a negative impact on health-related quality of life. Frequent comorbidity with potential prostatic disease adds complexity to the management of male LUTS. In this review, we discuss the pathophysiological conditions that underlie male LUTS, and examine the relationship between symptoms and urodynamic findings. The contribution of bladder dysfunction to male LUTS, with a particular emphasis on overactive bladder (OAB) symptoms, is explored. We also consider pharmacotherapeutic options for male LUTS. Pharmacotherapies that target the prostate (alpha1-receptor antagonists and 5alpha-reductase inhibitors) often fail to alleviate OAB symptoms, and may not be the most appropriate therapy for men with storage LUTS. Multiple studies have suggested that antimuscarinic therapy alone or in combination with alpha1-receptor antagonists improve OAB symptoms in men with and without bladder outlet obstruction. Although these agents may represent appropriate first-line therapies for men with OAB symptoms, the therapeutic potential of antimuscarinics alone or in combination with alpha1-receptor antagonists in this population should be evaluated in large-scale, well-designed clinical trials.

The Causes and Consequences of Overactive Bladder

Overactive bladder (OAB) is a syndrome characterized by symptoms of urinary urgency with or without urgency urinary incontinence (UUI), usually with frequency and nocturia. OAB affects approximately 17% of women in the United States and Europe. The causes of OAB, as with many bladder disorders, are multifactorial and are not completely understood. The primary functions of the lower urinary tract (bladder and bladder outlet mechanism) are storage and evacuation of urine. The bladder and the micturition cycle are under complex neural control involving both the sympathetic and parasympathetic nervous systems. Micturition may occur in response to the activation of receptors in the bladder muscle and detection of chemical stimuli by receptors within the bladder lining. Neurogenic or myogenic bladder dysfunction can lead to the symptoms of urgency, frequency, and UUI that characterize OAB. The consequences of this condition are far-reaching and include direct medical consequences and coping strategies that adversely affect quality of life. Although the prevalence of OAB increases with age, it is not a normal consequence of aging. Antimuscarinic agents (e.g., oxybutynin, tolterodine, trospium, solifenacin, and darifenacin) have demonstrated efficacy for the treatment of OAB symptoms in multiple clinical trials. This review explores the physiological basis for OAB, the effects of OAB on health-related quality of life, and the pharmacotherapies that may provide relief to patients with this distressing condition.

Sacral neuromodulation in lower urinary tract dysfunction

Vesico-urethral dysfunction is a major problem in daily medical practice due to its psychological disturbances, its social costs and its high impact on quality of life. Recently, sacral neuromodulation, namely the electrical stimulation of the sacral nerves, appears to have become an alternative for radical bladder surgery particularly in cases of idiopathic bladder overactivity. The mechanism of action is only partially understood but it seems to involve a modulation in the spinal cord due to stimulation of inhibitory interneurons. Temporary sacral nerve stimulation is the first step. It comprises the temporary application of neuromodulation as a diagnostic test to determine the best location for the implant and to control the integrity of the sacral root. If test stimulation is successful, a permanent device is implanted. This procedure is safe in experienced hands. So-called idiopathic bladder overactivity still the major indication for this technique. Patients not likely to benefit from the procedure were those with complete or almost complete spinal lesions, but incomplete spinal lesions seemed to be a potential indication. This technique is now also indicated in the case of idiopathic chronic retention and chronic pelvic pain syndrome. When selection is performed, more than three-quarters of the patients showed a clinically significant response with 50% or more reduction in the frequency of incontinent episodes, but the results vary according to the author's mode of evaluation. From the economic point of view, the initial investment in the device is amortized in the mid-term by savings related to lower urinary tract dysfunction. Finally, this technique requires an attentive follow-up and adjustments to the electric parameters so as to optimize the equilibrium between the neurological systems.

Alpha1 adrenoceptor subtypes in human urinary bladder: sex and regional comparison

A detailed study of the presence of alpha1 AR binding sites and alpha1 AR subtype mRNA expression in human urinary bladder areas involved in the micturition (i.e. detrusor, trigone and neck) is reported here, investigating whether or not there are differences between sexes. Results obtained indicated that alpha1 AR proteins were detectable in each bladder area. In both sexes, the detrusor and the neck expressed similar levels of alpha1 ARs: respectively, detrusor: 14.6 +/- 1.2 in men and 13.1 +/- 1.1 fmol/mg prot in women; neck: 16.9 +/- 3.2 in men and 17.5 +/- 4.1 fmol/mg prot in women. In the trigone, significantly higher alpha1ARs were found in women compared to men (20.6 +/- 1.1 vs 11.7 +/- 0.7 fmol/mg prot). Subtype analysis indicated that in women, each area was endowed with mRNA encoding for each alpha1 AR subtype. The men detrusor expressed alpha1a and alpha1d ARs, while in the trigone and the neck, each subtype was present. Since the detrusor muscle hypertrophy is a marker of bladder obstructive outlet, the selective alpha1 AR subtype targeting arouses much interest, as evidence indicates that there are differences in signalling pathways among the subtypes. Furthermore, the significance of the alpha1 ARs coexpression is still unknown; interestingly, recent papers demonstrate that alpha1 AR subtypes could dimerize. Thus, in the human urinary bladder it may be suggested a potential level of alpha1 AR complexity that could have an impact on drug development.

DETRUSOR OVERACTIVITY. DOES IT REPRESENT A DIFFERENCE IF PATIENTS FEEL THE INVOLUNTARY CONTRACTIONS?

PURPOSE

We evaluated the differences between patients with overactive bladder (OAB) who felt involuntary detrusor contractions during cystometry (detrusor overactivity [DO]) and those who did not feel them.

MATERIALS AND METHODS

We prospectively studied 45 patients with symptoms of nonneurogenic, nonobstructed overactive bladder and with DO on cystometry. All patients underwent videourodynamics, the ice water test and electrical perception threshold determination. Continence, urodynamic parameters, data from specific sensory evaluation and outcome of drug treatment were examined.

RESULTS

Almost half of our patients did feel the contractions of DO and half did not. The groups differed significantly. Those without DO sensation were more frequently incontinent, had more involuntary detrusor contractions and these occurred earlier during bladder filling. They had involuntary start of voiding more frequently, more pathological sensation of bladder filling and lower electrical sensory thresholds. The results of drug treatment were better in the group who felt DO.

CONCLUSIONS

Contractions of DO are felt by some of the patients and they differ from those patients who do not feel such contractions. It is likely that this finding reflects the existence of different OAB conditions with a different neuropathological cause and a different treatment outcome. Therefore, we suggest that specific tests for the evaluation of sensation in the lower urinary tract should be part of the diagnosis of patients with DO and symptoms of OAB.

Involvement of ryanodine receptors in muscarinic receptor-mediated membrane current oscillation in urinary bladder smooth muscle

The urinary bladder pressure during micturition consists of two components: an initial, phasic component and a subsequent, sustained component. To investigate the excitation mechanisms underlying the sustained pressure, we recorded from membranes of isolated detrusor cells from the pig, which can be used as a model for human micturition. Parasympathomimetic agents promptly evoke a large transient inward current, and subsequently during its continuous presence, oscillating inward currents of relatively small amplitudes are observed. The two types of inward current are considered to cause the phasic and sustained pressure rises, respectively. Ionic substitution and applications of channel blockers revealed that Ca(2+)-activated Cl(-) channels were responsible for the large transient and oscillating inward currents. Furthermore, the inclusion of guanosine 5'-O-(2-thiodiphosphate) in the patch pipette indicates that both inward currents involve G proteins. However, applications of heparin in the patch pipette and of xestospongin C in the bathing solution suggest a signaling pathway other than inositol 1,4,5-trisphosphate (IP(3)) operating in the inward current oscillations, unlike the initial transient inward current. This IP(3)-independent inward current oscillation system required both sustained Ca(2+) influx from the extracellular space and Ca(2+) release from the intracellular stores. These two requirements are presumably SKF-96365-sensitive cation channels and ryanodine receptors, respectively. Experiments with various Ca(2+) concentrations suggested that Ca(2+) influx from the extracellular space plays a major role in pacing the oscillatory rhythm. The fact that distinct mechanisms underlie the two types of inward current may help in development of clinical treatments of, for example, urinary incontinence and residual urine volume control.

ROLE OF C AFFERENT FIBERS AND MONITORING OF INTRAVESICAL RESINIFERATOXIN THERAPY FOR PATIENTS WITH IDIOPATHIC DETRUSOR OVERACTIVITY

PURPOSE

Resiniferatoxin (RTX) is a specific C fiber neurotoxin which produces desensitization. In this study we performed intravesical RTX therapy in patients with idiopathic detrusor overactivity. In addition we measured the current perception threshold of C and A delta fibers before and after treatment to evaluate clinical significance.

MATERIALS AND METHODS

The protocol involved an RTX solution (100 ml of 50 nM) instilled in the bladder for 30 minutes. Four men and 6 women 59 to 75 years old were treated. Effects on bladder function were evaluated before and 30 days after treatment by cystometry and Neurometer (Neurotron, Inc., Baltimore, Maryland). Subjective and objective measures included bladder diaries and quality of life before treatment, and 7, 30 and 90 days subsequently.

RESULTS

Of the 10 patients 5 noted improvement and 2 of them became dry. The other 5 patients were considered to have stationary symptoms. Mean maximal cystometric capacity +/- SD increased from 229 +/- 108 ml at baseline to 271 +/- 99.5 ml at 30 days (p = 0.04). The mean number of daily episodes of urinary incontinence decreased from 3.5 +/- 2.2 to 2.0 +/- 1.6 (p = 0.008) at 7 days, to 1.9 +/- 1.6 (p = 0.018) at 30 days and to 2.5 +/- 1.7 (p = 0.018) at 90 days. Mean current perception threshold values of C and A delta fibers did not change significantly, from 46.9 +/- 35.2 to 56.4 +/- 32.1 (p = 0.161) and from 66.9 +/- 31.7 to 66.4 +/- 25.2 (p = 0.952), respectively. However, values of C fibers increased in all patients who showed improvement from 46.2 +/- 33.2 to 64.0 +/- 36.8 (p = 0.043).

CONCLUSIONS

Intravesical RTX improved bladder capacity and leak episodes in patients with idiopathic detrusor overactivity. Intravesical RTX is a promising treatment for this condition.

The electrovesicogram in the overactive bladder: role in determining pathogenesis and diagnostic significance

We investigated the hypothesis that the abnormal contractility of the smooth musculature of the overactive bladder (OAB) may be due to derangement of its electrical activity. Percutaneous electrovesicography was performed in 22 patients (mean age 46.3 years, 12 men, ten women) with OAB and 14 healthy volunteers (mean age 45.6 years, eight men, six women). Recording was performed with the bladder full and empty. Three electrodes were applied suprapubically and one reference electrode was applied to a lower limb. Reproducible regular triphasic slow waves (SWs) were recorded in the volunteers. The pattern of the full and empty bladder were similar except for the higher amplitude of the waves in the former (P < 0.05). The OAB patients showed a "dysrhythmic" pattern with irregular frequency, amplitude and conduction velocity in both the empty and full bladders. We obtained tachyrhythmic, bradyrhythmic and arrhythmic areas in the same recording. The OAB exhibited a "dysrhythmic" electrical pattern with areas of different electrical activity in the same recording. The tachyrhythmic, bradyrhythmic and arrhythmic areas are suggested to explain the abnormal vesical contractions and clinical manifestations of OAB. Further studies are required to investigate the cause of the dysrhythmic pattern and the electrovesicogram is suggested as an investigative tool in OAB diagnosis.

Alteration in expression of myosin isoforms in detrusor smooth muscle following bladder outlet obstruction

Partial urinary bladder outlet obstruction (PBOO) in men, secondary to benign prostatic hyperplasia, induces detrusor smooth muscle (DSM) hypertrophy. However, despite DSM hypertrophy, some bladders become severely dysfunctional (decompensated). Using a rabbit model of PBOO, we found that although DSM from sham-operated bladders expressed nearly 100% of both the smooth muscle myosin heavy chain isoform SM-B and essential light chain isoform LC17a, DSM from severely dysfunctional bladders expressed as much as 75% SM-A and 40% LC17b (both associated with decreased maximum velocity of shortening). DSM from dysfunctional bladder also exhibited tonic-type contractions, characterized by slow force generation and high force maintenance. Immunofluorescence microscopy showed that decreased SM-B expression in dysfunctional bladders was not due to generation of a new cell population lacking SM-B. Metabolic cage monitoring revealed decreased void volume and increased voiding frequency correlated with overexpression of SM-A and LC17b. Myosin isoform expression and bladder function returned toward normal upon removal of the obstruction, indicating that the levels of expression of these isoforms are markers of the PBOO-induced dysfunctional bladders.