Pathophysiology of idiopathic overactive bladder and the success of treatment: a systematic review from ICI-RS 2013

Time of onset and factors associated with delayed response post intradetrusor injection of onabotulinumtoxin a in patients with neurogenic and idiopathic overactive bladder syndrome

Objective

The objective of this study was to determine risk factors for delayed response in patients with neurogenic and idiopathic overactive bladder (OAB) after intradetrusor onabotulinumtoxin A injection.

Subjects and Methods

This is a retrospective study that included 87 patients who underwent onabotulinumtoxin A intradetrusor injection from October 2011 to November 2019. Patients were followed up at 2, 4, and 12 weeks post intervention in the outpatient clinic and over the phone. The data of patients with early response were compared with those with late response using univariate and multivariate analyses.

Results

The study included 87 patients. The mean age was 41 ± 15.3 standard deviation, and 69% of the participants were female. Fifty-one percent were diagnosed with neurogenic OAB. A median response time to onabotulinumtoxin A injection of 7 days was demonstrated, and patients who responded during the first 7 days post procedure were considered early responders. Independent predictors for late response include diabetes (Relative risk: 3.89, P = 0.018, and 95% confidence interval [CI]: 1.26-11.98), >1 BTX-A session (Relative risk: 4, P = 0.011, and 95% CI: 1.38-11.6), and wet OAB (RR: 9.94, P = 0.002, and 95% CI: 2.31-42.17).

Conclusions

The median time of onset post intradetrusor injection of onabotulinumtoxin A was found to be 7 days. Diabetes mellitus, wet OAB, and <1 Botox sessions were independent risk factors for late onset of response.

Efficacy and safety of mirabegron in the treatment of overactive bladder syndrome after radical prostatectomy: a prospective randomized controlled study

Objectives

To evaluate the effects of mirabegron in the treatment of overactive bladder syndrome (OAB) after radical prostatectomy (RP).

Patients and methods

A total of 108 post-operative RP patients were randomly assigned to either the mirabegron (study) or the placebo (control) group. The Overactive Bladder Syndrome Self-Assessment Scale (OABSS) was selected as the primary endpoint, and the International Prostate Symptom Score (IPSS) and Quality of Life (QOL) score were selected as secondary endpoints. Statistical analysis was performed using IBM SPSS Statistics 26, and the treatment effects were compared between the two groups using independent samples t-test.

Results

In total, 55 patients were included in the study group and 53 patients in the control group. The mean age was(70.08 ± 7.54)years. There was no statistical difference in the baseline data between the two groups. OABSS scores decreased significantly in the study group compared to the control group during drug treatment (6.67 ± 1.06 vs. 9.14 ± 1.83, p < 0.01) and were better than the control group during the follow-up at week 8 and week 12. In addition, the decrease in IPSS scores (11.29 ± 3.89 and 15.34 ± 3.54, p<0.01) and the increase in QOL scores (2.40 ± 0.81 vs. 3.20 ± 1.00) were statistically significant in the study group. And the patients in the study group had better improvement in voiding symptoms and quality of life than the control group during the follow-up period.

Conclusion

Daily administration of 50 mg mirabegron after RP surgery significantly improved the symptoms of OAB after surgery with fewer side effects. Additional randomized controlled trials should be conducted in the future to further evaluate the efficacy and safety of mirabegron.

Evaluation of the effect of 100U of Onabotulinum toxin A on detrusor contractility in women with idiopathic OAB: A multicentre prospective study

Aims

Intradetrusor injection of Onabotulinum Toxin A (BTX‐A) is a third‐line treatment for overactive bladder (OAB). Voiding dysfunction and the need for intermittent catheterization are potential complications, consequent to bladder contractility (BC) decrement.

Primary aim: to evaluate BC variation after BTX‐A detrusor injection in women with idiopathic OAB.

Methods

A prospective multi‐institutional observational study was conducted. Medical history, bladder diary, 24‐h pad test, and invasive urodynamic parameters were recorded before and 4–6 weeks after BTX‐A 100U administration. BC was measured as Modified Projected Isovolumetric Pressure (PIP1), that is, maximum flow rate (Qmax) + detrusor pressure at Qmax (PdetQmax).

Continuous variables were expressed as median and interquartile range. We compared continuous variables using Wilcoxon test and proportions between two times with Fisher exact test.

Results

No changes in PIP1 were observed (p > 0.05) in 45 women enrolled between January 2018 and September 2019. Median age was 54.6 years. At baseline, 91.1% had urge urinary incontinence, with 4.9 ± 2.6 daily pads used and a 24‐h pad test of 205.4 ± 70.8 g. Baseline detrusor contractility was normal in all the patients.

Postoperatively, an improvement in the 24‐h pad test (p < 0.01), daily voids (p < 0.01), and nocturia (p < 0.01) occurred. Urodynamics pointed out a significant reduction of detrusor overactivity rate (p < 0.01) and an increase of median maximum cystometric capacity (p < 0.01). No difference was observed in median Qmax (p > 0.05), PdetQmax (p > 0.05), and PVR (p > 0.05). No patient needed postoperative catheterization.

Conclusions

The current series provides evidence that detrusor injection of botulinum toxin is an effective option for treating OAB, without causing voiding dysfunction and BC impairment.

Cognitive components of behavioral therapy for overactive bladder: a systematic review

INTRODUCTION AND HYPOTHESIS

Behavioral therapy is the first-line treatment for overactive bladder (OAB); however, the cognitive components of behavioral therapy for OAB have not been evaluated. The purposes of this systematic review were to describe the cognitive components of behavioral therapy for OAB and evaluate their effectiveness as well as to describe their rationale and origins.

METHODS

Searches were conducted on the PubMed, CINAHL, Web of Science, Cochrane and PEDro databases. Inclusion criteria were single-arm or randomized controlled trials on OAB treatment that utilized behavioral therapy, with a description of a cognitive component of the behavioral therapy. Study participants were neurologically intact adults (n = 1169). Study methodological quality was assessed with the PEDro and Newcastle-Ottawa scales.

RESULTS

Five studies were included, published between 2009 and 2020. Methodological quality was variable. All studies reported a reduction of symptoms in participants receiving behavioral therapy. Cognitive components of behavioral therapy were not extensively described. Distraction was the most common cognitive strategy for managing urgency. The relative impact of the cognitive aspect of behavioral therapy could not be evaluated, and the cognitive aspects of behavioral therapy appear to be accepted wisdom, traceable to several key authors, that has not been subjected to scientific investigation.

CONCLUSIONS

Behavioral therapy for OAB appears useful, but its cognitive components are not well described, their relative importance has not been evaluated or ascertained, nor have they been rigorously studied.

A Preliminary Study on the Impact of Detrusor Overactivity on the Efficacy of Selective Bladder Denervation for the Treatment of Female Refractory Overactive Bladder

OBJECTIVE

To determine whether the presence of detrusor overactivity (DO) is associated with the 12-week and 12-month clinical outcomes of selective bladder denervation (SBD) in women with refractory overactive bladder (OAB).

METHODS

Prospective single institutional study of refractory OAB females who underwent a urodynamic study and were categorized according to DO status (DO- vs DO+) prior to receiving SBD.

RESULTS

Among the 23 patients, 10 were DO- and 13 were DO+. Both groups reported improvement at 12 weeks on the 24-hour pad weight test, in urgency urinary incontinence (UUI) and urgency. At 12 months, both groups still reported improvement in urgency, but only the DO- group reported reduction on the pad weight test and only the DO+ group maintained improvement in the UUI rate. Clinical success (≥50% reduction in UUI) was achieved by all DO- and by 69% of DO+ patients at 12 weeks, and by 60% of DO- and 92% of DO+ patients at 12 months. Treatment benefit (Treatment Benefit Scale ≤2) was reported in 90% of DO- and 85% of DO+ patients at 12 weeks, and in 60% of DO- and 85% of DO+ patients at 12 months. When directly comparing both group outcomes, the only significant difference was the greater reduction of UUI in the DO- group at 12 weeks (-9.0 vs -6.5; P = .045).

CONCLUSION

Refractory OAB females appear to be effectively treated by SBD regardless of baseline DO status. DO status does not seem to be associated with the 12-week and 12-month outcomes of SBD.

Management of Overactive Bladder Symptoms After Radical Prostatectomy

PURPOSE OF REVIEW

Post-prostatectomy overactive bladder (OAB) is a common and challenging condition to manage. The aim of the present report was to review the recent evidences regarding OAB symptoms that develop in men after prostatectomy and how to manage them.

RECENT FINDINGS

The prevalence of OAB after radical prostatectomy may range from 15.2 to 37.8%. Recent studies have highlighted the role of the urethrogenic mechanism (facilitation of the urethrovesical reflex due to stress urinary incontinence (SUI)) in the genesis of post-prostatectomy OAB in a significant proportion of patients. Several other pathophysiological factors such as iatrogenic decentralization of the bladder, defunctionalized bladder due to severe SUI, detrusor underactivity, or bladder outlet obstruction might be involved. The evaluation should aim to identify the underlying mechanism to tailor the treatment, which could range from SUI surgery, to fixing a urethral stricture, improving bladder emptying or using the conventional spectrum of OAB therapies. There is a paucity of data for OAB therapies specific to post-prostatectomy patients, with the exception of solifenacin, tolterodine, and botulinum toxin. There is currently no data on how preoperative management or surgical technique may prevent post-prostatectomy OAB.

A prospective study investigating the diagnostic agreement between urodynamics and dynamic cystoscopy in women presenting with mixed urinary incontinence

INTRODUCTION AND HYPOTHESIS

Patient history is often insufficient to identify type of urinary incontinence (UI). Multichannel urodynamic testing (UDS) is often used to clarify the diagnosis. Dynamic cystoscopy (DC) is a novel approach for testing bladder function. The primary objective of this study was to investigate the diagnostic agreement of UDS and DC in evaluating women with mixed urinary incontinence (MUI).

METHODS

Women presenting with MUI were approached for enrollment if UDS and DC were planned for further investigation. Investigators were blinded to history and comparative test results. McNemar's test and kappa coefficient were calculated to assess agreement between UDS and DC. Receiver operating characteristic (ROC) analysis was used to explore the best possible filling sensation cutoffs for DC that would best predict the filling sensation cutoffs from UDS.

RESULTS

Sixty participants were included, of whom, four were excluded for protocol violation. For the primary outcome measure of agreement, UDS and DC were concordant in 44/56 of stress urinary incontinence (SUI) cases (79%) with a κ= 0.54 and in 43/56 of urinary urge incontinence (UUI) cases (77%) with a κ= 0.54, indicating moderate, nearly substantial agreement. ROC analysis identified the best prediction of DC first urge to void as 148 cm³, strong urge 215 cm³, and maximum capacity at 246 cm³. These parameters were used to compare UDS UUI to DC UUI and resulted in a κ = 0.61 (p = 0.37), indicating substantial agreement.

CONCLUSIONS

When compared with UDS, DC shows moderate agreement for detection of SUI and substantial agreement for detection of UUI.

Expressions of urothelial functional proteins in idiopathic detrusor overactivity patients refractory to antimuscarinic therapy with different urodynamic characteristics

AIMS

This study investigated the expressions of PGP9.5, P₂  X ₃ , muscarinic receptor (M3) and beta-3 adrenoreceptor (AR) in idiopathic detrusor overactivity (IDO) patients refractory to antimuscarinic treatment, and analyzed the correlation between protein expressions and clinical symptoms of IDO bladders with different urodynamic characteristics.

METHODS

Specimens of 48 IDO and 10 control patients without lower urinary tract symptoms were included. The levels of these proteins from bladder mucosa were determined by Western blotting.

RESULTS

The expression levels of β3-AR and M3 receptor were similar between IDO patients and controls. When IDO patients were divided into two subgroups, phasic DO and terminal DO, the results showed that β3-AR level in the patients with phasic DO was significantly higher than that of the controls and terminal DO (Both P < 0.05). PGP9.5 and P₂  X ₃ levels were also significantly increased in phasic DO subgroup than controls. P₂  X ₃ receptor was positively correlated with PGP9.5 and β3-AR, and negatively correlated with the first sensation of bladder filling and voided volume in phasic DO.

CONCLUSIONS

Similar expression M3 receptor and increased P₂  X ₃ levels in phasic DO, compared with the controls, indicate that dysregulation of purinergic bladder signaling may contribute to the pathogenesis of phasic DO refractory to antimuscarinics. Elevated expression of β3-AR in phasic DO but not in terminal DO patients may explain the different urodynamic characteristics of DO between the two subgroups. Our findings suggest that β3-AR agonist or P₂  X ₃ antagonist might be a good treatment choice for patients with phasic DO refractory to antimuscarinic therapy.

Does central sensitization help explain idiopathic overactive bladder?

The pathophysiological mechanisms underlying overactive bladder syndrome (OAB) can include dysfunction of sensory pathways of the peripheral and central nervous systems, resulting in bladder hypersensitivity. Central sensitization describes an induced state of spinal hypersensitivity that is associated with a variety of chronic pain disorders that share many attributes with OAB, albeit without the presence of pain. As such, the concept of central sensitization might be relevant to understanding the mechanisms and clinical manifestations of OAB syndrome. An understanding of the pathophysiology and clinical manifestations of central sensitization, and the evidence that supports a role of central sensitization in OAB, including the potential implications of mechanisms of central sensitization for the treatment of patients with OAB could provide a novel approach to the treatment of patients with this disease. Such an approach would be especially relevant to those patients with central sensitization-related comorbidities, and has the potential to improve the outcomes of these patients in particular.

[Prevalence and initial management of overactive bladder in France: A cross-sectional study]

AIMS

To determine the prevalence of overactive bladder (OAB) syndrome in France and gather data about initial patient trajectories in the healthcare system.

METHODS

A dedicated questionnaire (41 questions) has been sent to a 12,000 sample of people representative of the global population. The following data were investigated: social and demographic features, medical history, Urinary Symptom Profile questionnaire, bother, history of symptoms, care seeking and treatments received. Patient were considered having OAB in case if presenting at least two episodes of urgency per week, or being under treatment of OAB. OAB prevalence was the main outcome, and associated factors were characterized by univariate and multivariate analysis.

RESULTS

Based on 8842 available questionnaires, the global prevalence of OAB was estimated to be 14.4%. Prevalence was significantly higher in women, older age groups, as well as obesity, irritable bowel syndrome, urinary tract infections, enuresia, constipation, anxiety/depression, neurological diseases, sleep apnea syndrome, asthma, chronic obstructive pulmonary disease, diabetes and hypertension. Only 34.6% of patients with OAB had visited a health practitioner for this problem. General practitioners were most frequently implicated in patient primary care and evaluation. Seventy-two percent of patients with OAB had had additional investigations (mostly a urine culture) and only 6% of patients had to complete a bladder diary. The most frequent treatment option was oral antimuscarinics. Physical therapy and rehabilitation have been prescribed in 26% of cases, as well as dietary advice.

CONCLUSIONS

OAB is a frequent syndrome. Its prevalence increases with age, and OAB frequently concern elderly frail people with many other associated diseases.

LEVEL OF EVIDENCE

3.

Novel regulatory mechanism in human urinary bladder: central role of transient receptor potential melastatin 4 channels in detrusor smooth muscle function

Transient receptor potential melastatin 4 (TRPM4) channels are Ca(2+)-activated nonselective cation channels that have been recently identified as regulators of detrusor smooth muscle (DSM) function in rodents. However, their expression and function in human DSM remain unexplored. We provide insights into the functional role of TRPM4 channels in human DSM under physiological conditions. We used a multidisciplinary experimental approach, including RT-PCR, Western blotting, immunohistochemistry and immunocytochemistry, patch-clamp electrophysiology, and functional studies of DSM contractility. DSM samples were obtained from patients without preoperative overactive bladder symptoms. RT-PCR detected mRNA transcripts for TRPM4 channels in human DSM whole tissue and freshly isolated single cells. Western blotting and immunohistochemistry with confocal microscopy revealed TRPM4 protein expression in human DSM. Immunocytochemistry further detected TRPM4 protein expression in DSM single cells. Patch-clamp experiments showed that 9-phenanthrol, a selective TRPM4 channel inhibitor, significantly decreased the transient inward cation currents and voltage step-induced whole cell currents in freshly isolated human DSM cells. In current-clamp mode, 9-phenanthrol hyperpolarized the human DSM cell membrane potential. Furthermore, 9-phenanthrol attenuated the spontaneous phasic, carbachol-induced and nerve-evoked contractions in human DSM isolated strips. Significant species-related differences in TRPM4 channel activity between human, rat, and guinea pig DSM were revealed, suggesting a more prominent physiological role for the TRPM4 channel in the regulation of DSM function in humans than in rodents. In conclusion, TRPM4 channels regulate human DSM excitability and contractility and are critical determinants of human urinary bladder function. Thus, TRPM4 channels could represent promising novel targets for the pharmacological or genetic control of overactive bladder.

Regulation of Guinea Pig Detrusor Smooth Muscle Excitability by 17β-Estradiol: The Role of the Large Conductance Voltage- and Ca2+-Activated K+ Channels

Estrogen replacement therapies have been suggested to be beneficial in alleviating symptoms of overactive bladder. However, the precise regulatory mechanisms of estrogen in urinary bladder smooth muscle (UBSM) at the cellular level remain unknown. Large conductance voltage- and Ca²⁺-activated K⁺ (BK) channels, which are key regulators of UBSM function, are suggested to be non-genomic targets of estrogens. This study provides an electrophysiological investigation into the role of UBSM BK channels as direct targets for 17β-estradiol, the principle estrogen in human circulation. Single BK channel recordings on inside-out excised membrane patches and perforated whole cell patch-clamp were applied in combination with the BK channel selective inhibitor paxilline to elucidate the mechanism of regulation of BK channel activity by 17β-estradiol in freshly-isolated guinea pig UBSM cells. 17β-Estradiol (100 nM) significantly increased the amplitude of depolarization-induced whole cell steady-state BK currents and the frequency of spontaneous transient BK currents in freshly-isolated UBSM cells. The increase in whole cell BK currents by 17β-estradiol was eliminated upon blocking BK channels with paxilline. 17β-Estradiol (100 nM) significantly increased (~3-fold) the single BK channel open probability, indicating direct 17β-estradiol-BK channel interactions. 17β-Estradiol (100 nM) caused a significant hyperpolarization of the membrane potential of UBSM cells, and this hyperpolarization was reversed by blocking the BK channels with paxilline. 17β-Estradiol (100 nM) had no effects on L-type voltage-gated Ca²⁺ channel currents recorded under perforated patch-clamp conditions. This study reveals a new regulatory mechanism in the urinary bladder whereby BK channels are directly activated by 17β-estradiol to reduce UBSM cell excitability.

BK channel activators and their therapeutic perspectives

The large conductance calcium- and voltage-activated K⁺ channel (KCa1.1, BK, MaxiK) is ubiquitously expressed in the body, and holds the ability to integrate changes in intracellular calcium and membrane potential. This makes the BK channel an important negative feedback system linking increases in intracellular calcium to outward hyperpolarizing potassium currents. Consequently, the channel has many important physiological roles including regulation of smooth muscle tone, neurotransmitter release and neuronal excitability. Additionally, cardioprotective roles have been revealed in recent years. After a short introduction to the structure, function and regulation of BK channels, we review the small organic molecules activating BK channels and how these tool compounds have helped delineate the roles of BK channels in health and disease.