Detrusor underactivity and the underactive bladder: Symptoms, function, cause-what do we mean? ICI-RS think tank 2014: Detrusor Underactivity and the Underactive Bladder

How do we make progress in phenotyping patients with lower urinary tract such as overactive bladder and underactive detrusor, including using urine markers and microbiome data, to personalize therapy? ICI-RS 2023-Part 2

INTRODUCTION

Overactive bladder (OAB) and underactive bladder (UAB) could be associated with metabolic syndrome, affective disorders, sex hormone deficiency, changes in urinary microbiota, functional gastrointestinal disorders, or autonomic nervous system dysfunction.

OBJECTIVES

The aim of this Think Tank was to provide a guide on how to investigate OAB and/or detrusor underactivity (DU) patients to better clarify the underlying pathophysiology and possibly personalize the treatment.

METHODS

A compendium of discussion based on the current evidence related to phenotyping patients with OAB or DU using urodynamic tests, functional neuro-imaging, urinary markers, and microbiome.

RESULTS AND CONCLUSIONS

The article emphasizes the critical significance of adopting a comprehensive yet tailored approach to phenotyping patients with lower urinary tract (LUT) symptoms, such as OAB and UAB. The intricate interplay between the LUT and various factors, metabolic, neurological, psychological, and gastrointestinal can define unique LUT profiles, enabling personalized therapies to replace the one-size-fits-all approach.

Summary Paper on Underactive Bladder from the European Association of Urology Guidelines on Non-neurogenic Male Lower Urinary Tract Symptoms

BACKGROUND AND OBJECTIVE

The European Association of Urology (EAU) Guidelines Panel on non-neurogenic male lower urinary tract symptoms (LUTS) aimed to develop a new subchapter on underactive bladder (UAB) in non-neurogenic men to inform health care providers of current best evidence and practice. Here, we present a summary of the UAB subchapter that is incorporated into the 2024 version of the EAU guidelines on non-neurogenic male LUTS.

METHODS

A systematic literature search was conducted from 2002 to 2022, and articles with the highest certainty evidence were selected. A strength rating has been provided for each recommendation according to the EAU Guideline Office methodology.

KEY FINDINGS AND LIMITATIONS

Detrusor underactivity (DU) is a urodynamic diagnosis defined as a contraction of reduced strength and/or duration, resulting in prolonged bladder emptying and/or failure to achieve complete bladder emptying within a normal time span. UAB is a terminology that should be reserved for describing symptoms and clinical features related to DU. Invasive urodynamics is the only widely accepted method for diagnosing DU. In patients with persistently elevated postvoid residual (ie, >300 ml), intermittent catheterization is indicated and preferred to indwelling catheters. Alpha-adrenergic blockers are recommended before more invasive techniques, but the level of evidence is low. In men with DU and concomitant benign prostatic obstruction (BPO), benign prostatic surgery should be considered only after appropriate counseling. In men with DU and no BPO, a test phase of sacral neuromodulation may be considered.

CONCLUSIONS AND CLINICAL IMPLICATIONS

The current text represents a summary of the new subchapter on UAB. For more detailed information, refer to the full-text version available on the EAU website (https://uroweb.org/guidelines/management-of-non-neurogenic-male-luts).

PATIENT SUMMARY

The European Association of Urology guidelines on underactive bladder in non-neurogenic adult men are presented here. Patients must be fully informed of all relevant options and, together with their treating physicians, decide on the most optimal management for them.

Detrusor underactivity is associated with metabolic syndrome in aged primates

Lower urinary tract (LUT) dysfunction is prevalent in the elderly population, and clinical manifestations include urinary retention, incontinence, and recurrent urinary tract infections. Age-associated LUT dysfunction is responsible for significant morbidity, compromised quality of life, and rising healthcare costs in older adults, but its pathophysiology is not well understood. We aimed to investigate the effects of aging on LUT function by urodynamic studies and metabolic markers in non-human primates. Adult (n = 27) and aged (n = 20) female rhesus macaques were evaluated by urodynamic and metabolic studies. Cystometry showed detrusor underactivity (DU) with increased bladder capacity and compliance in aged subjects. Metabolic syndrome indicators were present in the aged subjects, including increased weight, triglycerides, lactate dehydrogenase (LDH), alanine aminotransferase (ALT), and high sensitivity C-reactive protein (hsCRP), whereas aspartate aminotransferase (AST) was unaffected and the AST/ALT ratio reduced. Principal component analysis and paired correlations showed a strong association between DU and metabolic syndrome markers in aged primates with DU but not in aged primates without DU. The findings were unaffected by prior pregnancies, parity, and menopause. Our findings provide insights into possible mechanisms for age-associated DU and may guide new strategies to prevent and treat LUT dysfunction in older adults.

Loss of resilience contributes to detrusor underactivity in advanced age

Volume hyposensitivity resulting from impaired sympathetic detrusor relaxation during bladder filling contributes to detrusor underactivity (DU) associated with aging. Detrusor tension regulation provides an adaptive sensory input of bladder volume to the brainstem and is challenged by physiological stressors superimposed upon biological aging. We recently showed that HCN channels have a stabilizing role in detrusor sympathetic relaxation. While mature mice maintain homeostasis in the face of stressors, old mice are not always capable. In old mice, there is a dichotomous phenotype, in which resilient mice adapt and maintain homeostasis, while non-resilient mice fail to maintain physiologic homeostasis. In this DU model, we used cystometry as a stressor to categorize mice as old-responders (old-R, develop a filling/voiding cycle) or old-non-responders (old-NR, fail to develop a filling/voiding cycle; fluctuating high pressures and continuous leaking), while also assessing functional and molecular differences. Lamotrigine (HCN activator)-induced bladder relaxation is diminished in old-NR mice following HCN-blockade. Relaxation responses to NS 1619 were reduced in old-NR mice, with the effect lost following HCN-blockade. However, RNA-sequencing revealed no differences in HCN gene expression and electrophysiology studies showed similar percentage of detrusor myocytes expressing HCN (I_h) current between old-R and old-NR mice. Our murine model of DU further defines a role for HCN, with failure of adaptive recalibration of HCN participation and intensity of HCN-mediated stabilization, while genomic studies show upregulated myofibroblast and fibrosis pathways and downregulated neurotransmitter-degradation pathways in old-NR mice. Thus, the DU phenotype is multifactorial and represents the accumulation of age-associated loss in homeostatic mechanisms.

Age‐related white matter hyperintensities and overactive bladder: A systematic review

INTRODUCTION

Age-related white matter hyperintensities (ARWMHs) on brain magnetic resonance imaging have been associated with lower urinary tract symptoms/dysfunction (LUTS/LUTD), namely overactive bladder (OAB) and detrusor overactivity. We aimed to systematically review existing data on the association between ARWMH and LUTS and which clinical tools have been used for this assessment.

MATERIALS AND METHODS

We searched PubMed/MEDLINE, Cochrane Library, and clinicaltrials.gov (from 1980 to November 2021) and considered original studies reporting data on ARWMH and LUTS/LUTD in patients of both sexes aged 50 or above. The primary outcome was OAB. We calculated the unadjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) for the outcomes of interest using random-effects models.

RESULTS

Fourteen studies were included. LUTS assessment was heterogeneous and mainly based on the use of nonvalidated questionnaires. Urodynamics assessment was reported in five studies. ARWMHs were graded using visual scales in eight studies. Patients with moderate-to-severe ARWMHs were more likely to present with OAB and urgency urinary incontinence (UUI; OR = 1.61; 95% CI: 1.05-2.49, p = 0.03), I²  = 21.3%) when compared to patients with similar age and absent or mild ARWMH.

DISCUSSION AND CONCLUSIONS

High-quality data on the association between ARWMH and OAB is scarce. Patients with moderate to severe ARWMH showed higher levels of OAB symptoms, including UUI, when compared to patients with absent or mild ARWMH. The use of standardized tools to assess both ARWMH and OAB in these patients should be encouraged in future research.

A Preclinical Study of Human Embryonic Stem Cell-Derived Mesenchymal Stem Cells for Treating Detrusor Underactivity by Chronic Bladder Ischemia

Background

The therapeutic effects of human embryonic stem cell-derived multipotent mesenchymal stem cells (M-MSCs) were evaluated for detrusor underactivity (DUA) in a rat model with atherosclerosis-induced chronic bladder ischemia (CBI) and associated mechanisms.

Methods

Sixteen-week-old male Sprague–Dawley rats were divided into five groups (n = 10). The DUA groups underwent 30 bilateral repetitions of endothelial injury to the iliac arteries to induce CBI, while the sham control group underwent a sham operation. All rats used in this study received a 1.25% cholesterol diet for 8 weeks. M-MSCs at a density of 2.5, 5.0, or 10.0 × 10⁵ cells (250 K, 500 K, or 1000 K; K = a thousand) were injected directly into the bladder 7 weeks post-injury, while the sham and DUA group were treated only with vehicle (phosphate buffer solution). One week after M-MSC injection, awake cystometry was performed on the rats. Then, the bladders were harvested, studied in an organ bath, and prepared for histological and gene expression analyses.

Results

CBI by iliac artery injury reproduced voiding defects characteristic of DUA with decreased micturition pressure, increased micturition interval, and a larger residual volume. The pathological DUA properties were improved by M-MSC treatment in a dose-dependent manner, with the 1000 K group producing the best efficacy. Histological analysis revealed that M-MSC therapy reduced CBI-induced injuries including bladder fibrosis, muscular loss, and apoptosis. Transplanted M-MSCs mainly engrafted as vimentin and NG2 positive pericytes rather than myocytes, leading to increased angiogenesis in the CBI bladder. Transcriptomes of the CBI-injured bladders were characterized by the complement system, inflammatory, and ion transport-related pathways, which were restored by M-MSC therapy.

Conclusions

Single injection of M-MSCs directly into the bladder of a CBI-induced DUA rat model improved voiding profiles and repaired the bladder muscle atrophy in a dose-dependent manner.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s12015-021-10204-z.

Frequency-Dependent Effects on Bladder Reflex by Saphenous Nerve Stimulation and a Possible Action Mechanism of Tibial Nerve Stimulation in Cats

Purpose

The present study determined the effects of saphenous nerve stimulation (SNS) at different stimulation frequencies on bladder reflex and explored a possible action mechanism of tibial nerve stimulation (TNS) on bladder activity in cats.

Methods

Two bipolar nerve cuff electrodes were implanted on the saphenous nerve and the contralateral tibial nerve in 13 cats, respectively. Multiple cystometrograms were obtained to determine the effects of single SNS at different frequencies and that of combined SNS and TNS on the micturition reflex by infusing normal saline.

Results

SNS at 1 Hz significantly reduced the bladder capacity (BC) to 59.8%±7.7% and 59.3%±5.8% of the control level at the intensity threshold (T) and 2T, respectively (P<0.05), while that at 20 Hz significantly increased the BC to 130.6%±4.2% of the control level at 6T (P<0.05). The TNS and SNS at 20 Hz did not significantly change the BCs at 1T (P>0.05), while combined stimulation at 1T significantly increased the BC to 122.7%±1.9% of the control level and induced an inhibitory effect which was similar to that TNS at 2T.

Conclusions

The current study revealed that SNS reduced and increased BC depending on different stimulation frequencies. The combined SNS and TNS maximized the clinical efficacy at a low intensity. Also, SNS may be a potential therapeutic mechanism of TNS.

Bladder underactivity induced by prolonged pudendal afferent activity in cats

The purpose of this study was to determine the effects of pudendal nerve stimulation (PNS) on reflex bladder activity and develop an animal model of underactive bladder (UAB). In six anesthetized cats, a bladder catheter was inserted via the urethra to infuse saline and measure pressure. A cuff electrode was implanted on the pudendal nerve. After determination of the threshold intensity (T) for PNS to induce an anal twitch, PNS (5 Hz, 0.2 ms, 2 T or 4 T) was applied during cystometrograms (CMGs). PNS (4-6 T) of 30-min duration was then applied repeatedly until bladder underactivity was produced. Following stimulation, control CMGs were performed over 1.5-2 h to determine the duration of bladder underactivity. When applied during CMGs, PNS (2 T and 4 T) significantly (P < 0.05) increased bladder capacity while PNS at 4 T also significantly (P < 0.05) reduced bladder contraction amplitude, duration, and area under contraction curve. Repeated application of 30-min PNS for a cumulative period of 3-8 h produced bladder underactivity exhibiting a significantly (P < 0.05) increased bladder capacity (173 ± 14% of control) and a significantly (P < 0.05) reduced contraction amplitude (50 ± 7% of control). The bladder underactivity lasted more than 1.5-2 h after termination of the prolonged PNS. These results provide basic science evidence supporting the proposal that abnormal afferent activity from external urethral/anal sphincter could produce central inhibition that underlies nonobstructive urinary retention (NOUR) in Fowler's syndrome. This cat model of UAB may be useful to investigate the mechanism by which sacral neuromodulation reverses NOUR in Fowler's syndrome.

The role of bladder wall thickness in the evaluation of detrusor underactivity: Development of a clinical nomogram

AIMS

The aim of our study was to investigate noninvasive predictors for detrusor underactivity (DUA) in male patients with lower urinary tract symptoms (LUTS) and benign prostatic enlargement (BPE).

METHODS

A consecutive series of patients aged 45 years or older with non-neurogenic LUTS were prospectively enrolled. Patients underwent standard diagnostic assessment including International Prostatic Symptoms Score, uroflowmetry, urodynamic studies (cystometry and pressure-flow studies), transrectal ultrasound of the prostate, and ultrasound measurements of the bladder wall thickness (BWT). Logistic regression analysis was used to investigate predictors of DUA, defined as a bladder contractility index < 100 mm H₂ O. A nomogram was developed based on the multivariable logistic regression model.

RESULTS

Overall 448 patients with a mean age of 66 ± 11 years were enrolled. In a multivariable logistic age-adjusted regression model BWT (odds ratio [OR]: 0.50 per mm; 95% confidence interval [CI], 0.30-0-66; P = .001) and Qmax (OR: 0.75 per mL/s; 95% CI, 0.70-0.81; P = .001) were significant predictors for DUA. The nomogram based on the model presented good discrimination (area under the curve [AUC]: 0.82), good calibration (Hosmer-Lemeshow test, P > .05) and a net benefit in the range of probabilities between 10% and 80%.

CONCLUSIONS

According to our results, BWT and Qmax can noninvasively predict the presence of DUA in patients with LUTS and BPE. Although our study should be confirmed in a larger prospective cohort, we present the first available nomogram for the prediction of DUA in patients with LUTS.

Do the definitions of the underactive bladder and detrusor underactivity help in managing patients: International Consultation on Incontinence Research Society (ICI-RS) Think Tank 2017?

AIMS

The Think Tank aimed to discuss the pitfalls and advantages of current definitions in terms of research and management of underactive bladder (UAB). UAB broadly defines a symptom complex of bladder emptying problems and does not indicate a specific pathology. Detrusor underactivity (DU) is a urodynamic diagnosis from pressure-flow studies. The correlation of UAB with DU remains to be precisely determined.

METHODS

The presentations and subsequent discussion, leading to research recommendations during the Think Tank of the International Consultation on Incontinence Research Society in Bristol, 2017, are summarized.

RESULTS

To develop more specific individualized management strategies, the Think Tank panel proposed (i) that, since defining a single type of index patient to represent all UAB will not fulfill all clinical research needs, several index patients should be defined by phenotyping of patients with UAB, including, children, young men and women, elderly male and female patients with co-existing DU and detrusor overactivity, and neurological patients with UAB; (ii) prospective longitudinal studies to assess the natural history of UAB, in the different target populations, based on different UAB phenotypes, should be initiated; (iii) DU should be precisely defined by urodynamic parameters; and (iv) work to develop validated specific questionnaires combined with non-invasive tests for screening, diagnosis and follow up, needs to be continued.

CONCLUSIONS

The precise relationship of UAB to DU remains to be defined. Phenotyping patients with UAB/DU, performing prospective trials of natural history, and developing symptom questionnaires and diagnostic investigations will improve our ability to identify and treat UAB/DU.

Bladder overactivity and post-void residual: Which relates more to systemic atherosclerotic markers?

OBJECTIVE

Several studies have shown relationship between the lower urinary tract dysfunction (LUTD) and atherosclerosis. However, no study is available to see which LUTD relates more to atherosclerosis, among detrusor overactivity and post-void residual. In order to answer this question, we present data of urodynamic and atherosclerosis tests.

METHODS

We performed standard urodynamics and two atherosclerosis tests, i.e., a cardio-ankle vascular stiffness index (CAVI) test and a duplex carotid ultrasonography.

PATIENTS

We have 183 patients; 109 men (mean age 66.3 years), 74 women (mean age 66.4 years); all age > 60 years.

RESULTS

Detrusor overactivity is related with high CAVI value (p < 0.05) but not with carotid intima-media thickness. Post-void residuals did not show such relation.

CONCLUSION

Urodynamic LUTD, particularly detrusor overactivity that may indicate central etiology is positively related with systemic atherosclerosis as measured by CAVI. Post-void residuals that may indicate peripheral etiology did not show such relation.

Novel symptom questionnaire for the differential diagnosis of detrusor underactivity and bladder outlet obstruction in men

OBJECTIVE

To develop a questionnaire for the differential diagnosis of detrusor underactivity (DUA) and bladder outlet obstruction (BOO) without performing invasive pressure flow studies.

STUDY DESIGN AND METHODS

Symptoms of men with DUA were analyzed and compared with those of men with BOO using eight questions from the developing questionnaire. Patients with DUA have a bladder contractility index (PdetQmax+5xQmax) less than 100, whereas those with BOO have a BOO index (PdetQmax-2xQmax) greater than 40 in urodynamic studies (UDS). Men with detrusor overactivity in UDS and neurogenic issues were excluded from the analysis. One urologist reviewed patients' medical records, and responded to eight questions without using information from UDS. Scores in the developing questionnaire were then compared to make a differential diagnosis between DUA and BOO.

RESULTS

Overall, 318 men who underwent UDS were included. Symptoms were compared in patients diagnosed with DUA without BOO (n = 165) and BOO without DUA (n = 153). Questions 1, 2, 4, 5, 6, and 7 were significantly different between groups. The sensitivity and specificity of the questionnaire were 95.8% and 95.4%, respectively, for predicting DUA in patients with scores greater than 45 points (cutoff value).

CONCLUSIONS

Men with DUA and BOO may be distinguished using a developing questionnaire without invasive evaluation. Men with scores greater than 45 points would be expected to have DUA but not BOO.

Lumbosacral radicular pain during micturition, defecation or orgasm

BACKGROUND

The objective of this study was to describe, in a cohort of patients followed for bladder, bowel or sexual dysfunctions, the occurrence of radicular pain during micturition, defecation and/or orgasm.

METHODS

The study included all patients referred in our neuro-urology department and who suffered from radicular pain before, during or after micturition, defecation and/or orgasm. Data included demographic and medical variables, urodynamic and perineal electromyographic diagnosis.

RESULTS

A total of 30 patients (men: 70%, mean age 45.4 ± 11.8,) complained of radicular pain before, during or after orgasm (51.4%), micturition (34.3%), or defecation (14.3%). In 30% of cases, radiculopathy was found and was predicted by micturition pain. Other pathologies were as follows: vertebral (16.5%), pelvis and sacral (16.5%), inflammatory central nervous system (10%) lesions and peripheral neuropathies (6.7%). Neurological level of injury was between the lumbar and the sacral level. All spinal cord lesions were lesions of the conus medullaris. Patients also complained of lower urinary tract symptoms (70%), sexual (63.3%) and bowel (60%) disorders. In most cases, the urodynamic diagnosis was neurogenic bladder with peripheral abnormalities and the electromyographic diagnosis was distal neuropathy.

CONCLUSION

Radicular pain occurring during micturition, defecation or orgasm is a rare condition. The most common underlying lesion seems to be radiculopathy, from lumbar to sacral spine. The presence of these symptoms, in the absence of any known neurological condition, should suggest the practitioner a radiculopathy in most of the cases. In consequence, appropriate additional tests should be offered to these patients.

SIGNIFICANCE

Few data are available on sciatica during micturition, defecation or orgasm. This study underlines the need for appropriate tests if a patient complaint from this type of symptom. Indeed, the most common underlying lesion is a radiculopathy but can also be a lesion of conus medullaris.

Bladder underactivity after prolonged stimulation of somatic afferent axons in the tibial nerve in cats

AIMS

To establish an animal model of bladder underactivity induced by prolonged and intense stimulation of somatic afferent axons in the tibial nerve.

METHODS

In seven cats under α-chloralose anesthesia, tibial nerve stimulation (TNS) of 30-min duration was repeatedly (3-8 times) applied at 4-6 times threshold (T) intensity for inducing a toe twitch to produce bladder underactivity determined by cystometry. Naloxone (1 mg/kg, i.v.) was administered to examine the role of opioid receptors in TNS-induced bladder underactivity.

RESULTS

After prolonged (1.5-4 h) and intense (4-6T) TNS, a complete suppression of the micturition reflex occurred in six cats and an increase in bladder capacity to about 150% of control and a decrease in the micturition contraction amplitude to 50% of control occurred in one cat. The bladder underactivity was maintained for at least 1-1.5 h. Naloxone reversed the bladder underactivity, but an additional 30-min TNS removed the naloxone effect.

CONCLUSIONS

The results indicate that prolonged and intense activation of somatic afferent axons in the tibial nerve can suppress the central reflex mechanisms controlling micturition. This animal model may be useful for examining the pathophysiology of neurogenic bladder underactivity and for development of new treatments for underactive bladder symptoms.

Recent advances in the understanding and management of underactive bladder

Underactive bladder (UAB) is an important and complex urological condition resulting from the urodynamic finding of detrusor underactivity. It can manifest in a wide range of lower urinary tract symptoms, from voiding to storage complaints, and can overlap with other conditions, including overactive bladder and bladder outlet obstruction. However, UAB continues to be poorly understood and inadequately researched. In this article, we review the contemporary literature pertaining to recent advances in defining, understanding, and managing UAB.

Early Surgical Intervention May Be More Likely to Cause Complications in Patients with Male Lower Urinary Tract Symptoms than To Prevent Them

There is no evidence that early surgical intervention will prevent complications due to bladder outlet obstruction, and a high likelihood that the surgery will bring its own complications.

Frailty and Lower Urinary Tract Symptoms

The incidence of both frailty and lower urinary tract symptoms, including urinary incontinence, overactive bladder, underactive bladder, and benign prostatic hyperplasia, increases with age. However, our understanding of the relationship between frailty and lower urinary tract symptoms, both in terms of pathophysiology and in terms of the evaluation and management of such symptoms, is greatly lacking. This brief review will summarize definitions and measurement tools associated with frailty and will also review the existing state of the literature on frailty and lower urinary tract symptoms in older individuals.

Male Incontinence: The Etiology or Basis of Treatment

CONTEXT

Elderly men are an increasing proportion of the aging population in the 21st century. Urinary incontinence reduces the quality of life and increases the burden of care for the aging population.

OBJECTIVE

The primary objective of this review is to explore the etiopathology of common causes of incontinence in aging male patients. The focus is on the algorithm of the initial evaluation of these patients from both a primary care and a urologic standpoint.

EVIDENCE ACQUISITION

A nonsystematic review of the literature was performed in September 2017. The data and evidence of this paper have been obtained by a PubMed search, and through official statements and recommendations from the International Consultation on Incontinence. Our search incorporated terms such as elderly, urinary incontinence, male, urodynamics, bladder outlet obstruction, BPH, neurologic, urethral stricture, spinal shock, and urethral sphincter injury.

EVIDENCE SYNTHESIS

A total of 7204 papers were identified; 6838 were excluded for female populations and populations <65 yr. A broad differential diagnosis exists for urinary incontinence in aging male patients, and many patients will be found to have multifactorial incontinence, compounding the issue. Neurologic etiologies common in this population include cerebrovascular accidents, Parkinson's disease, and dementia. Spinal cord injuries and multiple sclerosis are less common. In this analysis, non-neurologic etiologies leading to incontinence are broadly grouped under bladder outlet obstruction, sphincter injury, overactive bladder, underactive bladder, polypharmacy, and urinary tract infections.

CONCLUSIONS

We provide a review of the differential diagnosis of incontinence in an elderly male patient. There is a need for understanding etiopathology and recognizing that many patients may have a combination of the above. The assessment algorithm, modified from the International Continence Society, provides a pathway for the provider in evaluating and treating elderly patients.

PATIENT SUMMARY

In this review, we have identified the sources of urinary incontinence in elderly male patients by neurologic and non-neurologic causes. We also discuss the basic evaluation and workup of an incontinent patient.

Phenotyping the detrusor underactivity: Is it more important than categorizing the symptomatic presentation of detrusor underactivity?

AIMS

Recently, [Brown et al Neurourol Urodyn. 36:1151-1154, 2017] reported a remarkable study regarding detrusor underactivity (DU) by categorizing the possible phenotypes. Although this study presents novel findings on the possible phenotypes, several points need to be clarified further for a better understanding.

METHODS

The methodology, especially regarding categorizing the phenotypes has been reviewed and comments have been added for better understanding of their study.

RESULTS

To better understand novel results of their study, several points have to be considered, which include cluster analysis and categorization according to symptomatic presentations.

CONCLUSIONS

Phenotyping by either etiologies or covariates and by syndromic presentations is not easy. Due to the aging features, multiple factors are needed during interpretation of the categorized phenotypes. Considering the advantage of the clinical benefit from the patient's viewpoint, categorization of syndromic symptomatic presentation using multiple validated tools including patient-reported outcomes is needed.

Epidemiology of underactive bladder: Common but underresearched

Detrusor underactivity (DU) or underactive bladder is a common cause of lower urinary tract symptoms (LUTS), but it is still poorly understood and underresearched. Although there has been a proposed definition by International Continence Society in 2002, no widely accepted diagnostic criteria have been established for this entity in clinical practice. Therefore, it has been rare to identify community-based researches on the epidemiology of DU until now. Only certain studies have reported the prevalence of DU in community-dwelling cohorts with significant LUTS using arbitrary urodynamic criteria for DU and these investigations have indicated that DU accounts for 25%–48% and 12%–24% of elderly men and women, respectively. However, these prevalence data based on the urodynamic definition apparently are limited in their extrapolation to the general population. Despite the clinical ambiguity of DU, its clinical effects on quality of life are quite significant, especially in the elderly population. An overall and proper comprehension of epidemiologic studies of DU may be crucial for better insight into DU, relevant decision making, and a more reasonable allocation of health resources. Therefore, researchers should find clues to the solution for the clinical diagnosis of this specific condition of LUTS from contemporary epidemiologic studies and try to develop a possible definition of ‘clinical’ DU from further studies.

Saphenous nerve stimulation normalizes bladder underactivity induced by tibial nerve stimulation in cats

This study in α-chloralose-anesthetized cats aimed at investigating the bladder responses to saphenous nerve stimulation (SNS). A urethral catheter was used to infuse the bladder with saline and to record changes in bladder pressure. With the bladder fully distended, SNS at 1-Hz frequency and an intensity slightly below the threshold (T) for inducing an observable motor response of the hindlimb muscles induced large amplitude (40-150 cmH₂O) bladder contractions. Application of SNS (1 Hz, 2-4T) during cystometrograms (CMGs), when the bladder was slowly (1-3 ml/min) infused with saline, significantly ( P < 0.05) increased the duration of the micturition contraction to >200% of the control without changing bladder capacity or contraction amplitude. Repeated application (1-8 times) of intense (4-8T intensity) 30-min tibial nerve stimulation (TNS) produced prolonged post-TNS inhibition that significantly ( P < 0.01) increased bladder capacity to 135.9 ± 7.6% and decreased the contraction amplitude to 44.1 ± 16.5% of the pre-TNS control level. During the period of post-TNS inhibition, SNS (1 Hz, 2-4T) applied during CMGs completely restored the bladder capacity and the contraction amplitude to the pre-TNS control level and almost doubled the duration of the micturition contraction. These results indicate that SNS at 1 Hz can facilitate the normal micturition reflex and normalize the reflex when it is suppressed during post-TNS inhibition. This study provides an opportunity to develop a novel neuromodulation therapy for underactive bladder using SNS.

An excitatory reflex from the superficial peroneal nerve to the bladder in cats

This study in α-chloralose-anesthetized cats discovered an excitatory peroneal nerve-to-bladder reflex. A urethral catheter was used to infuse the bladder with saline and record bladder pressure changes. Electrical stimulation was applied to the superficial peroneal nerve to trigger reflex bladder activity. With the bladder distended at a volume ~90% of bladder capacity, superficial peroneal nerve stimulation (PNS) at 1-3 Hz and threshold (T) intensity for inducing muscle twitching on the posterior thigh induced large-amplitude (40-150 cmH₂O) bladder contractions. PNS (1-3 Hz, 1-2T) applied during cystometrograms (CMGs) when the bladder was slowly (1-3 ml/min) infused with saline significantly (P < 0.01) reduced bladder capacity to ~80% of the control capacity and significantly (P < 0.05) enhanced reflex bladder contractions. To determine the impact of PNS on tibial nerve stimulation (TNS)-induced changes in bladder function, PNS was delivered following TNS. TNS of 30-min duration produced long-lasting poststimulation inhibition and significantly (P < 0.01) increased bladder capacity to 140.5 ± 7.6% of the control capacity. During the post-TNS inhibition period, PNS (1-3 Hz, 1-4T) applied during CMGs completely restored bladder capacity to the control level and significantly (P < 0.05) increased the duration of reflex bladder contractions to ~200% of control. The excitatory peroneal nerve-to-bladder reflex could also be activated by transcutaneous PNS using skin surface electrodes attached to the dorsal surface of the foot. These results raise the possibility of developing novel neuromodulation therapies to treat underactive bladder and nonobstructive urinary retention.

Pathophysiology of the Underactive Bladder: Evolving New Concepts

PURPOSE OF REVIEW

Underactive Bladder (UAB) is an emerging concept of voiding dysfunction, building on a tradition of often overlapping and confusing terminologies describing the patient experience, urodynamic function, and pathophysiology. This confusion of symptoms with function with pathology has hampered development of an effective disease model.

RECENT FINDINGS

As with other urinary symptoms, the relationship of voiding symptoms to urodynamic dysfunction is variable. Efforts are underway to formally define UAB as a collection of symptoms related to voiding. Defined as voiding symptoms, UAB cannot be reliably linked to detrusor underactivity (DU) nor to detrusor weakness.

SUMMARY

Progress will be made by characterizing the functional disorders underlying UAB symptoms, examining the biology of these linkages, re-conceptualizing urinary control as one part of a more global biologic adaptive physiology, and determining the relationships of central and peripheral pathologies leading to disrupted control mechanisms.

Non-neurogenic Chronic Urinary Retention: What Are We Treating?

PURPOSE OF REVIEW

This review examines current terminology used to define non-neurogenic chronic urinary retention (CUR), describes the pathophysiology of urinary retention, and highlights contemporary diagnostic and treatment algorithms.

RECENT FINDINGS

There is no standardized definition for the condition, but volumes >300 ml are commonly used to describe CUR. It is a clinical diagnosis which does not require urodynamics. Pathophysiologic causes of CUR be from myogenic, neurogenic, bladder outlet obstruction, or a combination of these sources. Treatment algorithms recommend stratifying patients with chronic urinary retention by risk and by symptoms before initiating treatment. Common CUR outcome endpoints need to be better utilized so that treatment modalities can be compared. Non-neurogenic CUR is a heterogeneous condition that has multiple definitions, underlying physiologies, and possible endpoints. Standardization is needed to better understand and treat CUR.

Changes in Adenosine Triphosphate and Nitric Oxide in the Urothelium of Patients with Benign Prostatic Hyperplasia and Detrusor Underactivity

PURPOSE

We investigated changes in the levels of adenosine triphosphate and nitric oxide in the urothelium of men with detrusor underactivity and benign prostatic hyperplasia.

MATERIALS AND METHODS

We prospectively enrolled in study 30 men who planned to undergo surgical treatment for benign prostatic hyperplasia. The 15 patients with a bladder contractility index less than 100 were assigned to the detrusor underactivity group while the 15 with a bladder contractility index more than 100 were assigned to the no detrusor underactivity group. Bladder mucosal specimens were collected at surgical prostate resection, and adenosine triphosphate and endothelial nitric oxide synthase were analyzed in these specimens. The levels of adenosine triphosphate and endothelial nitric oxide synthase were compared between the 2 groups. The correlation of urodynamic parameters with adenosine triphosphate and endothelial nitric oxide synthase was assessed in all patients.

RESULTS

Mean ± SEM endothelial nitric oxide synthase did not significantly differ between the detrusor underactivity and no underactivity groups (3.393 ± 0.969 vs 1.941 ± 0.377 IU/ml, p = 0.247). However, the mean level of adenosine triphosphate in the detrusor underactivity group was significantly lower than in the no detrusor underactivity group (1.289 ± 0.320 vs 9.262 ± 3.285 pmol, p = 0.011). In addition, in all patients adenosine triphosphate positively correlated with the bladder contractility index (r = 0.478, p = 0.018) and with detrusor pressure on maximal flow (r = 0.411, p = 0.046).

CONCLUSIONS

Adenosine triphosphate was significantly decreased in the urothelium in men with detrusor underactivity and benign prostatic hyperplasia, reflecting the change in detrusor function.

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.

Phenotyping women with detrusor underactivity by presumed etiology: Is it plausible?

AIMS

Underactive bladder (UAB) is a symptom complex with poorly characterized causation. The aim of this study was to determine if clinical and UDS parameters differed between categories of presumed detrusor underactivity (DU) etiologies.

METHODS

A retrospective review was performed at a single institution from 2011 to 2015 to identify patients with symptoms of UAB. Patients were excluded if they were male, had anti-incontinence, or pelvic organ prolapse (POP) surgery within 1 year, or the UDS did not demonstrate DU as defined within. Subjects were stratified by etiology into four cohorts: cardiovascular disease manifestations (CV), cardiac risk factors (CVR), neurologic (N), or idiopathic (I). Patient demographics, comorbidities, symptomatology, physical exam, and UDS parameters were compared.

RESULTS

A total of 200 patients met inclusion criteria (CV: n = 53 [26.5%], CVR: n = 44 [22%] N: n = 81 [40.5%], I: n = 22 [11%]). Women in the CV cohort were significantly older and more likely to be post-menopausal (P < 0.001). There were no differences between cohorts for BMI (P = 0.48), recurrent UTI (P = 0.63), history of urinary retention (AUR) (P = 0.65), POP (0.49), American Urological Association Symptom Score (AUA-SS) (P = 0.06), presenting symptomatology [urgency, frequency, urgency urinary incontinence, AUR, incomplete emptying, hesitancy, UTI (P = 0.97)], or UDS parameters (first sensation [P = 0.25], normal desire [P = 0.80], strong desire [P = 0.58], capacity [P = 0.11], Qmax [P = 0.50], Pdet at Qmax [P = 0.22], post-void residual [P = 0.82]).

CONCLUSIONS

Though differences were observed between cohorts for age and menopausal status, clinical or urodynamic parameters did not demonstrate distinct differences across presumed categories of etiology, suggesting that the etiology of DU may be multifactorial. Neurourol. Urodynam. 36:1151-1154, 2017. © 2016 Wiley Periodicals, Inc.

Addressing challenges in underactive bladder: recommendations and insights from the Congress on Underactive Bladder (CURE-UAB)

Underactive bladder (UAB) is an expanding troublesome health issue, exerting a major influence on the health and independence of older people with a disproportionally low level of attention received. The 2nd International Congress on Underactive Bladder (CURE-UAB 2) convened in Denver, CO on December 3 and 4, 2015, and comprised of top clinicians, scientists, and other stakeholders to address the challenges in UAB. A series of workshops aimed to define UAB and its phenotype, define detrusor underactivity (DU) and create a subtyping of DU, evaluate existing animal models for DU, and lastly to establish research priorities for UAB.

Urothelial ATP signaling: what is its role in bladder sensation?

AIM

Bladder functional disorders are common health problems; however, their pathologies are poorly understood. Adenosine triphosphate (ATP) released from the urothelium has been suggested to have an essential role in the micturition reflex, and its involvement in bladder functional disorders has been intensively investigated. Here, we review the latest advances in research on urothelial ATP signaling.

METHODS

We reviewed research articles on the role of the urothelium and urothelial ATP release in bladder function.

RESULTS

Mice lacking purinergic receptors have been reported to exhibit marked bladder hyporeflexia. Based on this observation, it was commonly believed, according to the widely held ATP urothelial signaling theory, that stretch-induced urothelial ATP release mediates the sensation of bladder filling via purinergic receptors. However, recent studies employing novel experimental methods and approaches have demonstrated that there are no significant differences in bladder function between wild-type and purinergic receptor knockout mice under physiological conditions. Nonetheless, under pathological conditions, inhibition of purinergic receptors has been shown to improve bladder hyperactivity. Moreover, enhanced urothelial ATP release has been reported in patients with bladder functional disorders.

CONCLUSIONS

Recently, conflicting evidence has led us to question the role of urothelial ATP signaling in normal micturition reflex. In contrast, under pathological conditions, it seems likely that enhanced urothelial ATP signaling mediates bladder hyperactivity. These recent findings suggest that the urothelial ATP signaling pathway is a potential therapeutic target for bladder functional disorders.