On the nature of bladder sensation: the concept of sensory modulation

Prevention of Lower Urinary Tract Symptoms Research Consortium Focus Group Study of Habits, Attitudes, Realities, and Experiences of Bladder Health

AIM

The study purpose is to explore adolescent and adult women's experiences, perceptions, beliefs, knowledge and behaviors related to bladder health across the life course using a socioecological perspective. Lower urinary tract symptoms affect between 20-40% of young adult to middle-aged women, with symptoms increasing in incidence and severity with aging. There is limited evidence to address bladder health promotion and prevention of dysfunction. This first study of the Prevention of Lower Urinary Tract Symptoms (PLUS) Research Consortium is designed to address gaps in existing qualitative research in this area.

DESIGN

This focus group study will be implemented across seven geographically diverse United States research centers using a semi-structured focus group guide informed by a conceptual framework based on the socioecological model.

METHODS

The study was approved in July 2017. A total of 44 focus groups composed of 6-8 participants representing six different age categories (ranging from 11 to over 65 years) will be completed. We aim to recruit participants with diverse demographic and personal characteristics including race, ethnicity, education, socioeconomic status, urban/rural residence, physical/health conditions and urinary symptom experience. Up to 10 of these focus groups will be conducted in Spanish. Focus group transcripts will undergo content analysis and data interpretation to identify and classify themes and articulate emerging themes.

DISCUSSION

This foundational qualitative study seeks to develop an evidence base to inform future research on bladder health promotion in adolescent and adult women.

IMPACT

This study has the potential to provide new insights and understanding into adolescent and adult women's lived experience of bladder health, the experience of lower urinary symptoms and knowledge and beliefs across the life course. This article is protected by copyright. All rights reserved.

Correlation between Heart Rate Variability and Bladder Sensations During Filling and Voiding Phase of Urodynamic Study in Patients with Myelopathy

Objective:

The objective of this study was to correlation between heart rate variability (HRV) and bladder sensations during filling and voiding phase of urodynamic study (UDS) in patients with myelopathy.

Materials and Methods:

Myelopathy patients (traumatic and nontraumatic) within 6 months of illness were included in the study. Demographic data, etiopathological diagnosis, and urinary complaints were noted. UDS was performed and simultaneous HRV calculated at each event of filling and voiding phase by recording and calculating standard deviation of normal-to-normal (NN) interval (SDNN), root mean square of successive differences, total power (TP), average heart rate, high frequency (HF), low-frequency (LF) ratio, and data analyzed.

Results:

The study included 30 patients (23 males) with a mean age of 31.2 years (range 18–60 years, standard deviation 11.6). The mean of LF in normalized units showed an increase from 43.6 ± 14.1 at baseline to 48.9 ± 17.4 at strong desire to void (SDV) and at urgency to 44.1 ± 14.5. HF at baseline 40.4 ± 14.1 reduced to 36.4 ± 12.8 at SDV and rose at urgency to 41.2 ± 13.2. LF/HF at baseline was 1.3 ± 0.8, which increased to 1.6 ± 1.1 at SDV and reduced at urgency to 1.2 ± 0.6. Significant change in mean value was seen in TP (P = 0.01) and SDNN (P = 0.009) at first desire to void. Significant positive trend was seen in TP (P = 0.048) and SDNN (P = 0.042) during filling.

Conclusion:

Comparison of HRV measures failed to show significant rise in sympathetic or parasympathetic component in myelopathy patients during UDS and requires more critical evaluation.

An innovative, non-invasive sensation meter allows for a more comprehensive understanding of bladder sensation events: A prospective study in participants with normal bladder function

AIMS

There is currently no standardized method of characterizing changes in bladder sensation during bladder filling outside of the urodynamics laboratory. The purpose of this investigation was to characterize real-time bladder sensation events using a sensation meter during oral hydration in individuals with normal bladder function.

METHODS

Participants enrolled in an accelerated hydration study drank 2 L Gatorade-G2® and utilized a sensation meter to record real-time bladder sensation (0-100%), verbal sensory thresholds, and sensation descriptors of "tense," "pressure," "tingling," "painful," and "other" for two consecutive fill-void cycles.

RESULTS

Data from 21 participants (12 females/9 males) were obtained and demonstrated an average of 8-9 sensation events (significant changes in sensation) per fill with no differences in the total number of sensation events and volume between sensation events (fill 1 vs fill 2). An increased number of sensation events occurred at higher capacity quartiles. Event descriptors of "pressure" and "tingling" were the most commonly chosen descriptors in both fills.

CONCLUSIONS

The innovative sensation meter includes the sensation event descriptors of "tense," "tingling," "pressure," and "painful," to enable a more comprehensive understanding of bladder sensation as well as real-time identification, quantification, and characterization of sensation events. The study demonstrates 8-9 events per fill, acceleration of sensation during filling, and unique sensation event descriptor patterns. This technology may be helpful in the identification of novel sensation patterns associated with overactive bladder (OAB) and aging.

Non-invasive characterization of real-time bladder sensation using accelerated hydration and a novel sensation meter: An initial experience

AIMS

The purpose of this investigation was to develop a non-invasive, objective, and unprompted method to characterize real-time bladder sensation.

METHODS

Volunteers with and without overactive bladder (OAB) were prospectively enrolled in a preliminary accelerated hydration study. Participants drank 2L Gatorade-G2® and recorded real-time sensation (0-100% scale) and standardized verbal sensory thresholds using a novel, touch-screen "sensation meter." 3D bladder ultrasound images were recorded throughout fillings for a subset of participants. Sensation data were recorded for two consecutive complete fill-void cycles.

RESULTS

Data from 14 normal and 12 OAB participants were obtained (ICIq-OAB-5a = 0 vs. ≥3). Filling duration decreased in fill2 compared to fill1, but volume did not significantly change. In normals, adjacent verbal sensory thresholds (within fill) showed no overlap, and identical thresholds (between fill) were similar, demonstrating effective differentiation between degrees of %bladder capacity. In OAB, within-fill overlaps and between-fill differences were identified. Real-time %capacity-sensation curves left shifted from fill1 to fill2 in normals, consistent with expected viscoelastic behavior, but unexpectedly right shifted in OAB. 3D ultrasound volume data showed that fill rates started slowly and ramped up with variable end points.

CONCLUSIONS

This study establishes a non-invasive means to evaluate real-time bladder sensation using a two-fill accelerated hydration protocol and a sensation meter. Verbal thresholds were inconsistent in OAB, and the right shift in OAB %capacity-sensation curve suggests potential biomechanical and/or sensitization changes. This methodology could be used to gain valuable information on different forms of OAB in a completely non-invasive way.

Prostatic inflammation induces urinary frequency in adult mice

Lower urinary tract symptoms (LUTS) including urinary frequency and nocturia are common in aging men. Recent studies have revealed a strong association of prostatic inflammation with LUTS. We developed an animal model of bacterial induced, isolated prostatic inflammation and examined the effect of prostatic inflammation on voiding behavior in adult C57BL/6J mice. Prostatic inflammation was induced by transurethral inoculation of uropathogenic E. coli—1677. Bacterial cystitis was prevented by continuous administration of nitrofurantoin. Hematoxylin and eosin (H&E) staining and bacterial culture were preformed to validate our animal model. Voiding behavior was examined by metabolic cage testing on post-instillation day 1 (PID 1), PID 4, PID 7 and PID 14 and both voiding frequency and volume per void were determined. Mice with prostatic inflammation showed significantly increased voiding frequency at PID 1, 7 and 14, and decreased volume per void at all time points, as compared to mice instilled with saline and receiving nitrofurantoin (NTF). Linked analysis of voiding frequency and voided volumes revealed an overwhelming preponderance of high frequency, low volume voiding in mice with prostatic inflammation. These observations suggest that prostatic inflammation may be causal for symptoms of urinary frequency and nocturia.

The concept of peripheral modulation of bladder sensation

It is recognized that, as the bladder fills, there is a corresponding increase in sensation. This awareness of the volume in the bladder is then used in a complex decision making process to determine if there is a need to void. It is also part of everyday experience that, when the bladder is full and sensations strong, these sensations can be suppressed and the desire to void postponed. The obvious explanation for such altered perceptions is that they occur centrally. However, this may not be the only mechanism. There are data to suggest that descending neural influences and local factors might regulate the sensitivity of the systems within the bladder wall generating afferent activity. Specifically, evidence is accumulating to suggest that the motor-sensory system within the bladder wall is influenced in this way. The motor-sensory system, first described over 100 years ago, appears to be a key component in the afferent outflow, the afferent "noise," generated within the bladder wall. However, the presence and possible importance of this complex system in the generation of bladder sensation has been overlooked in recent years. As the bladder fills the motor activity increases, driven by cholinergic inputs and modulated, possibly, by sympathetic inputs. In this way information on bladder volume can be transmitted to the CNS. It can be argued that the ability to alter the sensitivity of the mechanisms generating the motor component of this motor-sensory system represents a possible indirect way to influence afferent activity and so the perception of bladder volume centrally. Furthermore, it is emerging that the apparent modulation of sensation by drugs to alleviate the symptoms of overactive bladder (OAB), the anti-cholinergics and the new generation of drugs the β 3 sympathomimetics, may be the result of their ability to modulate the motor component of the motor sensory system. The possibility of controlling sensation, physiologically and pharmacologically, by influencing afferent firing at its point of origin is a "new" concept in bladder physiology. It is one that deserves careful consideration as it might have wider implications for our understanding of bladder pathology and in the development of new therapeutic drugs. In this overview, evidence for the concept peripheral modulation of bladder afferent outflow is explored.

Brain responses to bladder filling in older women without urgency incontinence

AIMS

To investigate normal brain responses to bladder filling, especially when there is little or no sensation as in much of daily life.

METHODS

We performed an functional magnetic resonance imaging (fMRI) study of brain responses to bladder filling in normal female subjects, evoked by infusion and withdrawal of fluid in and out of the bladder. Using the contrast (infusion-withdrawal), we imaged brain activity at small bladder volumes with weak filling sensation and also with full bladder and strong desire to void.

RESULTS

Eleven women, average age 65 years (range: 60-71 years) were included. With full bladder and strong desire to void, filling provoked a well-known pattern of activation near the right insula and (as a trend) in the dorsal anterior cingulate cortex and supplementary motor area. There was no significant deactivation. With small bladder volume filling provoked widespread apparent deactivation and no significant activation. Apparent deactivation was associated with increased fMRI signal during withdrawal rather than decrease during infusion, suggesting artifact. A correction for global changes in cerebral blood flow eliminated it and revealed significant subcortical activation, although none in frontal or parietal cortex.

CONCLUSIONS

In older women with normal bladder function, infusion into an already full bladder resulted in strong sensation and brain activation near the insula and in the dorsal anterior cingulate/supplementary motor complex. With near-empty bladder and little sensation, the situation during much of daily life, these cortical areas were not detectably activated, but activation in midbrain and parahippocampal regions presumably indicated unconscious monitoring of ascending bladder signals.