Sensory urgency: how full is your bladder?

A Comprehensive Review of Overactive Bladder Pathophysiology: On the Way to Tailored Treatment

CONTEXT

Current literature suggests that several pathophysiological factors and mechanisms might be responsible for the nonspecific symptom complex of overactive bladder (OAB).

OBJECTIVE

To provide a comprehensive analysis of the potential pathophysiology underlying detrusor overactivity (DO) and OAB.

EVIDENCE ACQUISITION

A PubMed-based literature search was conducted in April 2018, to identify randomised controlled trials, prospective and retrospective series, animal model studies, and reviews.

EVIDENCE SYNTHESIS

OAB is a nonspecific storage symptom complex with poorly defined pathophysiology. OAB was historically thought to be caused by DO, which was either "myogenic" (urgency initiated from autonomous contraction of the detrusor muscle) or "neurogenic" (urgency signalled from the central nervous system, which initiates a detrusor contraction). Patients with OAB are often found to not have objective evidence of DO on urodynamic studies; therefore, alternative mechanisms for the development of OAB have been postulated. Increasing evidence on the role of urothelium/suburothelium and bladder afferent signalling arose in the early 2000s, emphasising an afferent "urotheliogenic" hypothesis, namely, that urgency is initiated from the urothelium/suburothelium. The urethra has also recently been regarded as a possible afferent origin of OAB-the "urethrogenic" hypothesis. Several other pathophysiological factors have been implicated, including metabolic syndrome, affective disorders, sex hormone deficiency, urinary microbiota, gastrointestinal functional disorders, and subclinical autonomic nervous system dysfunctions. These various possible mechanisms should be considered as contributing to diagnostic and treatment algorithms.

CONCLUSIONS

There is a temptation to label OAB as "idiopathic" without obvious causation, given the poorly understood nature of its pathophysiology. OAB should be seen as a complex, multifactorial symptom syndrome, resulting from multiple potential pathophysiological mechanisms. Identification of the underlying causes on an individual basis may lead to the definition of OAB phenotypes, paving the way for personalised medical care.

PATIENT SUMMARY

Overactive bladder (OAB) is a storage symptom syndrome with multiple possible causes. Identification of the mechanisms causing a patient to experience OAB symptoms may help tailor treatment to individual patients and improve outcomes.

Clinical and urodynamic differences among women with overactive bladder according to the presence of detrusor overactivity

INTRODUCTION AND HYPOTHESIS

We tried to determine whether clinical and urodynamic differences exist between women with and without detrusor overactivity (DO) using a large database of overactive bladder (OAB) patients.

METHODS

We reviewed the medical records of 513 women who underwent urodynamic studies for OAB symptoms without neurogenic or anatomical conditions that affect micturition function. Clinical symptoms were evaluated using a 3-day frequency-volume chart (FVC) including the Urinary Sensation Scale and American Urological Association Symptom Index (AUA-SI). All clinical and urodynamic findings were compared between women with and without DO.

RESULTS

The patients' mean age was 58.9 years. DO was identified urodynamically in 167 (32.6 %) women. Those with DO were older (62.9 vs 57.0 years, p < 0.001); however, no differences in AUA-SI, episodes of daytime voiding, and episodes of nocturia were observed between the groups. Functional bladder capacity was smaller in women with DO; however, this difference did not reach statistical significance. Women with DO had significantly more urgency incontinence symptoms than those without DO (55.1 vs 29.5 %, p < 0.001). In urodynamic parameters, the volumes at first desire to void and strong desire to void and maximum cystometric capacity were significantly smaller, and detrusor pressure at the opening was significantly higher in women with DO compared to subjects without DO (26.2 vs 21.2 cmH(2)O, p = 0.004).

CONCLUSIONS

Our findings suggest a more severe disturbance of bladder function when DO exists, although no differences were observed in symptom scores and 3-day FVC parameters among women with OAB symptoms according to the presence of DO.

Which method is the most reliable in determination of bladder capacity in children with idiopathic overactive bladder? A comparison of maximum voided volume, uroflowmetry and maximum cystometric capacity

OBJECTIVE

To compare uroflowmetry, maximum cystometric capacity and maximum voided volume in terms of bladder capacity (BC) estimation in children with idiopathic overactive bladder.

MATERIALS AND METHODS

A total of 84 children with idiopathic overactive bladder were enrolled. Bladder diaries were kept by parents to measure maximum voided volume. The sum of voided volume and post-void residual urine represented uroflowmetric BC. Maximum cystometric capacity was recorded for each patient. Patients with and without urge incontinence and both sexes were compared, and correlations were tested between estimated capacities, patient age and continence status.

RESULTS

Mean age was 10.88 (range 6-16) years. There were 52 females and 32 males. A total of 48 patients had urge incontinence (group 1), and the remaining 36 (group 2) did not. Mean bladder capacities were 165.44ml for uroflowmetry, 204.37ml for cystometry and 260.07ml for bladder diary. Maximum cystometric capacity and capacity in terms of maximum voided volume by diary were significantly higher in patients without urge incontinence. There were significant correlations between age and all other variables, and between the presence of urge incontinence and all variables except maximum cystometric capacity. There were significant differences between bladder capacities estimated by the three methods; however, on age-adjusted re-analysis this significance was lost.

CONCLUSION

There is no significant difference between BCs estimated by uroflowmetry, maximum cystometric capacity and maximum voided volume in children with idiopathic overactive bladder. Bladder diary is a reliable and non-invasive way of estimating BC in this patient population.

Defining overactive bladder as hypersensitivity

Overactive bladder (OAB), according to the International Continence Society (ICS) definition, is a symptom syndrome, with urgency as the cornerstone symptom. However, the word 'urgency' and its definition continue to be the subject of much debate and confusion. It is generally difficult for patients to differentiate urgency from normal urge, particularly when the desire to void is strong. To investigate the micturition behavior associated with OAB, we conducted a Patient Trust Study in 21 intelligent (i.e., to be 'trusted') female patients who could clearly and accurately discriminate between urgency and urge. The results showed that in 43% of patients seeking medical care, urgency episodes occurred less than once/day, and some patients had days without urgency. Our patients deferred voiding until bladder sensation was relatively strong, suggesting that coping was not common among these patients. Four of the 21 patients studied experienced spontaneous resolution of several urgency episodes. At volumes exceeding 40% of the maximum bladder volume (MBV), urgency episodes occurred frequently and independently of the bladder volume, indicating that 40% of the MBV may be a threshold of bladder volume to induce urgency. A linear relationship was observed between bladder volume and increasing bladder sensation. However, compared with normal subjects, urge sensation increased markedly at any given bladder volume among patients with OAB in our study. This hypersensitivity was observed in our patients regardless of urgency episodes. We therefore hypothesized that OAB may be more accurately defined as a hypersensitivity disorder rather than a syndrome characterized by urgency.

A case series to pilot cognitive behaviour therapy for women with urinary incontinence

OBJECTIVE

Psychological factors have been identified with respect to female urinary incontinence. However, there is limited research regarding psychological interventions. The effectiveness of cognitive behaviour therapy (CBT) as a treatment for women with urinary incontinence was investigated.

DESIGN

The study adopted an AB case series design with a follow-up phase.

METHODS

Ten women with urinary incontinence each attended individual sessions. The Hospital anxiety and depression scale (HADS) and Incontinence Quality of Life (I-QOL) were administered pre-treatment, post-treatment, and 3-months post-treatment. Participants kept weekly records of bladder functioning. An unstandardized client satisfaction questionnaire was administered at 3-months post-treatment.

RESULTS

Anxiety and depression, as measured by the HADS did not show any significant changes. Improvements in incontinence-related quality of life reached statistical significance at the post-treatment administration and were maintained at the 3-months post-treatment follow-up. Significant changes in bladder functioning were not apparent until the 3-month post-treatment follow-up. The satisfaction questionnaires suggest that the participants found the intervention of value.

CONCLUSIONS

The findings of this study tentatively suggest that incontinence-related quality of life might be improved by involvement in a CBT intervention. Some modest improvements occurred in bladder functioning. Further research is required to confirm these findings.

Is sensory urgency part of the same spectrum of bladder dysfunction as detrusor overactivity?

It has been suggested that the urogynecological diagnosis of sensory urgency is an early form of detrusor overactivity and may be just earlier in the spectrum of disease. The former term is generally defined as increased perceived bladder sensation during filling, a low first desire to void and low bladder capacity in the absence of recorded urinary tract infection (UTI) or detrusor overactivity. The aims of this study are to determine the prevalence and associations of sensory urgency in comparison with detrusor overactivity, and whether sensory urgency is shown to be in the same spectrum of bladder dysfunction as detrusor overactivity. Five hundred and ninety-two women attending for an initial urogynecological/urodynamic assessment took part in this prospective study. In addition to a full clinical assessment, all women underwent free uroflowmetry, residual urine volume measurement (by vaginal ultrasound) and multichannel filling and voiding cystometry. Data were separated into those having (1) sensory urgency or (2) detrusor overactivity. Apart from prevalence figures, comparative associations were sought for (3) age; (4) parity; (5) presenting symptoms; (6) presence of at least one (medically) documented UTI in the previous 12 months; (7) two or more (recurrent) documented UTIs in the previous 12 months; (8) prior hysterectomy; (9) prior continence surgery; (10) menopause; (11) menopause and HRT use; (12) sign of clinical stress leakage; (13) retroverted uterus; (14) anterior vaginal wall prolapse; (15) uterine prolapse; (16) posterior vaginal wall prolapse; (17) apical vaginal prolapse; (18, 19) maximum, average urine flow rate (MUFR, AUFR) centiles, Liverpool Nomograms; (20) median residual urine volume (RUV) in milliliters; (21, 22) voiding difficulty: VD1,VD2 (MUFR, AUFR under 10th centile Liverpool Nomogram and/or RUV >30 ml); (23) diagnosis of urodynamic stress incontinence and (24) diagnosis of uterine and/or vaginal prolapse (grade >0). The prevalence of sensory urgency was 13%. The only differences in the clinical and urodynamic profiles of it and detrusor overactivity were (1) significantly increased prevalence of the symptom of urge incontinence and (2) (by definition) abnormal detrusor contractions during filling cystometry in women with detrusor overactivity. Overall, sensory urgency and detrusor overactivity appear to be part of the same spectrum of bladder dysfunction.

Stress incontinence surgery for patients presenting with mixed incontinence and a normal cystometrogram

OBJECTIVE

To evaluate the outcome of surgery for stress urinary incontinence (SUI) in patients presenting with a combination of stress and sensory urge UI.

PATIENTS AND METHODS

The study comprised 75 women presenting with mixed incontinence; the most important inclusion criterion was a negative cystometrogram for detrusor overactivity. Based on random selection, a third of the patients received a 6-month course of anticholinergic treatment (group 1) and 50 (group 2) had surgery for SUI. The surgical procedure depended on the Valsalva leak-point pressure (VLPP); those with a VLPP of > or = 90 cmH2O underwent Burch retropubic bladder neck suspension (group 2a, 24 patients) while 26 (group 2b) with a VLPP of < 90 cmH2O had pubovaginal sling (PVS) surgery. A further group of 20 patients with pure SUI (no urge UI) underwent surgery (PVS in 12 and Burch in eight) as a control group (group 3). After at least 6 months of follow-up (mean 9.3, sd 1.7), 68 patients were evaluable; they were assessed subjectively and objectively for dryness, and by a urodynamic evaluation and quantitative assessment using the SEAPI scoring system.

RESULTS

In group 1 none of the patients became completely dry; there was persistent stress with and without urge UI in nine (43%) and 12 (57%) of the available 21 patients, respectively. Only three of those who had persistent SUI with no urge in the whole study group were satisfied and chose to continue anticholinergic therapy despite SUI. In this group the mean (sd) improvement in the subjective and objective SEAPI score was 3.4 (1.0) and 2.3 (3.8), respectively. In group 2a, 20 of the available 23 patients (87%) became completely dry (both stress and urge continent). The mean improvement in the SEAPI scores was 7.8 (0.9) and 7.8 (1.3), respectively. In group 2b, 20 of the 24 patients (83%) became completely dry, with mean improvements in SEAPI scores of 8.2 (0.4) and 7.9 (0.3), respectively. The improvement was statistically significant after surgery, vs anticholinergic therapy, for all variables (P < 0.05). The incidence of persistent urge UI was highest in group 1 (43%), being 13% in group 2 (13% and 12% in 2a and b, respectively). In group 3 there was de novo urge UI in four of the 20 patients, and not significantly different from that in group 2.

CONCLUSION

Most patients with mixed stress and urge UI and a normal cystometrogram were cured of both symptoms by surgery. The incidence of residual urge in such patients was no higher than that of de novo urge after surgery in patients with genuine SUI.

Estrous influences on micturition thresholds of the female rat before and after bladder inflammation

Recent evidence suggests that lower urinary tract functions may be influenced by reproductive status, particularly under pathophysiological conditions. This study used repeated cystometrograms via a transurethral catheter to investigate the influence of estrous stage on micturition thresholds before and after turpentine-induced bladder inflammation in urethane-anesthetized female rats. Whereas there were no estrous influences on micturition threshold in the uninflamed bladder, micturition thresholds after bladder inflammation were significantly lower in rats in proestrus or estrus than in rats in metestrus or diestrus. Furthermore, the risk that the initial urethral catheterization and preinflammation cystometrogram would produce hematuria was significantly lower in estrus than in the other stages. These estrous influences are not readily explicable by levels of ovarian hormones at the time of testing and may relate instead to dynamic interactions between these hormones and other neuroactive molecules. In addition, the results here have relevance to interpretations of cystometrographic findings in the clinic and basic research.

Brain responses to changes in bladder volume and urge to void in healthy men

Knowledge of how changes in bladder volume and the urge to void affect brain activity is important for understanding brain mechanisms that control urinary continence and micturition. This study used PET to evaluate brain activity associated with different levels of passive bladder filling and the urge to void. Eleven healthy male subjects (three left- and eight right-handed) aged 19-54 years were catheterized and the bladder filled retrogradely per urethra. Twelve PET scans were obtained during two repetitions of each of six bladder volumes, with the subjects rating their perception of urge to void prior to and after each scan. Increased brain activity related to increasing bladder volume was seen in the periaqueductal grey matter (PAG), in the midline pons, in the mid-cingulate cortex and bilaterally in the frontal lobe area. Increased brain activity relating to decreased urge to void was seen in a different portion of the cingulate cortex, in premotor cortex and in the hypothalamus. Both activation patterns were predominantly bilaterally symmetric and none of the effects could be attributed to the presence of the catheter. However, in some subjects, mostly those reporting intrusive sensations from the urethral catheter, there was a discrepancy between filling volume and urge so that they reported high urge with low volumes. As this 'mismatch' decreased, activation increased bilaterally in the somatosensory cortex. Our findings support the hypothesis that the PAG receives information about bladder fullness and relays this information to areas involved in the control of bladder storage. Our results also show that the network of brain regions involved in modulating the perception of the urge to void is distinct from that associated with the appreciation of bladder fullness.

Mixed symptomatology

Mixed symptomatology, i.e. both stress and urge incontinence, is reported by patients, either of their own accord or in response to a questionnaire. Our understanding of motor urge incontinence, detrusor instability, stress incontinence and sensory urge incontinence is changing. Detrusor instability is now known to be a urodynamic observation of uncertain clinical significance. Symptoms reported by patients are not equivalent to a urodynamic diagnosis but the problem seems to be more in the urodynamics than in the symptoms. Evidence shows that sensory urge incontinence and motor urge incontinence are probably gradations of the same condition. The relationship between stress incontinence and an overactive bladder is complex. For example, neither detrusor instability nor urge incontinence appear to adversely influence the outcome of surgical treatment for stress incontinence; however, this treatment does not have a good success rate. At present, it is not clear whether this poor outcome reflects a lack of efficacy of the operations used, or their application to inappropriate patients.

Diagnosis and significance of idiopathic overactive bladder

OBJECTIVES

To offer a critical overview of the basis for the International Continence Society (ICS) classification of detrusor instability, to summarize current diagnostic methodologies, and to outline the etiologic factors that should be excluded in the diagnosis of idiopathic overactive bladder.

METHODS

The current ICS definitions of overactive bladder are discussed. Issues related to the diagnosis of detrusor instability (DI) are addressed through a review of the literature.

RESULTS

The term idiopathic overactive bladder reflects the present lack of knowledge concerning vesicourethral function and dysfunction. The term is used to apply to a wide spectrum of different conditions that may have a common final pathophysiologic pathway. This heterogeneous group of conditions could be subdivided on the basis of presumptive etiopathogenesis, urodynamic patterns, and response to treatment. The diagnosis of DI, its rate of detection, and its urodynamic patterns depend on the type of urodynamic test used and the way the test is performed. The ICS definitions of DI have been called into question by the results of studies using urodynamic tests in addition to, or instead of, provocative cystometry--for instance, ambulatory urodynamics, urethrocystometry, the ice-water test, and evaluation of the voiding phase. The literature supports a broadening of the ICS criteria for excluding all known causes of DI when establishing the diagnosis of idiopathic overactive bladder.

CONCLUSIONS

Appropriate longitudinal studies, using contemporary urodynamic tests and knowledge, are needed to improve the identification of subsets of patients with overactive bladder who have different prognoses and outcomes. The ICS definitions and classification should be updated.

Age-associated changes in detrusor sensory function in women with lower urinary tract symptoms

This study examined changes in bladder sensation which occur with age in women. 1381 women (age range 20-95 years, mean 54.9) with symptoms of lower urinary tract dysfunction underwent urodynamic study. The bladder capacity at which they first became aware of the desire to void was taken as a quantitative measure of bladder sensation. Maximum bladder capacity fell in the eighth and ninth decades (H = 95.84, df = 7, P = 0.00), but by contrast bladder capacity at first desire to void rose progressively in association with age, both in the group as a whole (H = 17.13, df = 7, P = 0.017) and in a subgroup with detrusor instability (n = 952, H = 15.42, df = 7, P = 0.032). This rise in capacity points to a decrease in bladder sensation in association with age. This is not due to neurological disease, anti-muscarinic drugs or oestrogens, as the median capacity at first desire to void of these three subgroups did not differ significantly from that of the group as a whole.

Urethral sensitivity in the aetiology of sensory urgency

OBJECTIVE

To investigate urethral hypersensitivity as a cause of sensory urgency.

PATIENTS AND METHODS

Twenty women with sensory urgency and 10 normal controls were enrolled in the study. A urethral conductance catheter was designed comprising three pairs of electrodes. These were accurately located in the urethra using the principle of urethral electrical conductance. The urethral sensory threshold was then measured at three sites along the urethral by applying a stimulatory current across each pair of electrodes in turn.

RESULTS

The women with sensory urgency had significantly higher thresholds for urethral stimulation along the whole urethra when compared with the control group.

CONCLUSION

Urethral hypersensitivity was not found to be a feature of sensory urgency and in fact the converse was demonstrated. This has not been described before. High sensory thresholds may occur with small fibre peripheral neuropathies. Thus, peripheral neuropathy is potentially a factor in the, as yet unknown, aetiology of sensory urgency.

Bladder sensory power factor (BSPF): a novel diagnostic tool

A simple clinical test for assessment of sensory function of the urinary bladder is described. It is performed during urodynamic assessment, consisting of stepwise filling of the bladder by gas. Subjects give numerical description of the perceived magnitude of pressure at each step, using an open-ended ratio scale. Based on Stevens law of psychophysics, the bladder sensory power factor (BSPF) is extracted from these data, reflecting the sensory state of the bladder. A BSPF of 1.01 +/- 0.12 (mean +/- SD) was found for 13 normal subjects. For 20 patients with lower urinary tract complaints who had a lesion of lumbosacral nerve roots, the BSPF was 0.59 +/- 0.23 (P < 0.001, t-test). In 16 (80%) of them BSPF was lower than 0.77 (= normal mean -2 SDs), being markedly more sensitive than the punctual sensory parameters-bladder sensory threshold (25%) or capacity (35%). BSPF is presented as a sensitive and easy to perform test for assessment of the sensory function of the human urinary bladder.