Human brain region response to distention or cold stimulation of the bladder: a positron emission tomography study

Functional brain networks associated with the urge for action: Implications for pathological urge

Tics in Tourette syndrome (TS) are often preceded by sensory urges that drive the motor and vocal symptoms. Many everyday physiological behaviors are associated with sensory phenomena experienced as an urge for action, which may provide insight into the neural correlates of this pathological urge to tic that remains elusive. This study aimed to identify a brain network common to distinct physiological behaviors in healthy individuals, and in turn, examine whether this network converges with a network we previously localized in TS, using novel 'coordinate network mapping' methods. Systematic searches were conducted to identify functional neuroimaging studies reporting correlates of the urge to micturate, swallow, blink, or cough. Using activation likelihood estimation meta-analysis, we identified an 'urge network' common to these physiological behaviors, involving the bilateral insula/claustrum/inferior frontal gyrus/supplementary motor area, mid-/anterior- cingulate cortex (ACC), right postcentral gyrus, and left thalamus/precentral gyrus. Similarity between the urge and TS networks was identified in the bilateral insula, ACC, and left thalamus/claustrum. The potential role of the insula/ACC as nodes in the network for bodily representations of the urge to tic are discussed.

Anatomy, physiology, and evaluation: Bowel, bladder, and sexual disorders

Our present understanding of bowel and bladder control has changed dramatically with the introduction of functional imagining technologies such as PET, SPECT, fMRI scanning, and near-infrared spectroscopy of the brain. Urologists tend to see control of urination and defecation as processes that occurred at or below the level of the pons for the most part. In this chapter, we examine the control of storing and emptying of urine and stool from what will be a more neurocentric perspective, integrating the frontal lobes into the process and moving beyond the pons on which most of the literature has focused in the past. Utilizing this approach gives us a better understanding of why there is an overlapping of neuropsychiatric problems in many patients with voiding dysfunction.

Intrathecal Baclofen for Spasticity: Is There an Effect on Bladder Function? Report of Three Cases and Review of the Literature

INTRODUCTION

traumatic brain injury (TBI) is very often associated with spasticity. Medical interventions may include medications such as baclofen, a Gamma-Aminobutyric Acid (GABA) -receptor agonist of poor lipid solubility. Intrathecal baclofen (ITB) administration is a contemporary treatment option which minimizes adverse effects in contrast with the oral form of the drug. Regarding low urinary tract dysfunction, TBI, as a suprapontine lesion, results in neurogenic detrusor overactivity. Frequency, urgency and urge incontinence are the predominant signs and symptoms of this condition. Our study aims to report the potential changes in bladder function in patients with spasticity, due to TBI, after the implantation of the baclofen pump and the control of spasticity.

MATERIAL AND METHODS

We report three cases of TBI whose spasticity responded well to ITB. We evaluated our medical reports regarding bladder function retrospectively, before and after baclofen pump implantation. We compared the data of bladder diaries and urodynamic parameters.

RESULTS

Bladder function was improved in all patients. Regarding bladder diaries; the number of incontinence and micturition episodes was decreased and the volume per void was slightly increased. Regarding urodynamic parameters; bladder capacity and reflex volume increased, Pdetmax decreased, PVR was the same and DLPP was slightly decreased.

CONCLUSIONS

Although the baclofen pump is implanted to treat spasticity, detrusor activity may be also affected. Therefore, patients' urologic profiles should also be reevaluated after ITB. Further prospective studies are required to investigate the effect of ITB on bladder function in the clinical field and also at the basic science level.

Abnormal resting-state functional connectivity of hippocampal subregions in children with primary nocturnal enuresis

Objective

Previous neuroimaging studies have shown abnormal brain-bladder control network in children with primary nocturnal enuresis (PNE). The hippocampus, which has long been considered to be an important nerve center for memory and emotion, has also been confirmed to be activating during micturition in several human imaging studies. However, few studies have explored hippocampus-related functional networks of PNE in children. In this study, the whole resting-state functional connectivity (RSFC) of hippocampus was investigated in children with PNE.

Methods

Functional magnetic resonance imaging data of 30 children with PNE and 29 matched healthy controls (HCs) were analyzed in our study. We used the seed-based RSFC method to evaluate the functional connectivity of hippocampal subregions defined according to the Human Brainnetome Atlas. Correlation analyses were also processed to investigate their relationship with disease duration time, bed-wetting frequency, and bladder volume.

Results

Compared with HCs, children with PNE showed abnormal RSFC of the left rostral hippocampus (rHipp) with right fusiform gyrus, right Rolandic operculum, left inferior parietal lobule, and right precentral gyrus, respectively. Moreover, decreased RSFC of the left caudal hippocampus (cHipp) with right fusiform gyrus and right supplementary motor area was discovered in the PNE group. There were no significant results in the right rHipp and cHipp seeds after multiple comparison corrections. In addition, disease duration time was negatively correlated with RSFC of the left rHipp with right Rolandic operculum (r = -0.386, p = 0.035, uncorrected) and the left cHipp with right fusiform gyrus (r = -0.483, p = 0.007, uncorrected) in the PNE group, respectively. In the Receiver Operating Characteristic (ROC) analysis, all the above results of RSFC achieved significant performance.

Conclusions

To our knowledge, this is the first attempt to examine the RSFC patterns of hippocampal subregions in children with PNE. These findings indicated that children with PNE have potential dysfunctions in the limbic network, sensorimotor network, default mode network, and frontoparietal network. These networks may become less efficient with disease duration time, inducing impairments in brain-bladder control, cognition, memory, and emotion. Further prospective research with dynamic observation of brain imaging, bladder function, cognition, memory, and emotion is warranted.

Relationships between overactive bladder and cerebral white matter hyperintensity in outpatients at a memory clinic

AIM

Cerebral small vessel disease and lower urinary tract symptoms are common in older people. However, the association between white matter hyperintensity (WMH) and overactive bladder (OAB) is not fully understood. We aimed to identify the relationship between WMH and OAB.

METHODS

We carried out neuropsychological testing and head magnetic resonance imaging (T2-weighted and fluid-attenuated inversion recovery) of 72 outpatients at a memory clinic and evaluated their Overactive Bladder Symptom Score. WMH was assessed using the Fazekas scale, and WMH volumes were determined using Software for Neuro-Image Processing in Experimental Research. OAB was diagnosed based on a urinary urgency score (the third question of the Overactive Bladder Symptom Score) of two or higher and a total Overactive Bladder Symptom Score of three or higher. Multivariate logistic analysis was carried out, with the presence/absence of overactive bladder as the outcome variable, and age, sex, body mass index and diabetes mellitus as covariates.

RESULTS

Of the 72 participants, 17 (24%) were diagnosed with OAB. WMH assessed by the visual rating scale was not associated with OAB. However, participants with OAB showed significantly higher WMH volume than those without OAB. Regionally, participants with OAB showed high WMH volume in the frontal, occipital and parietal lobes. Multiple logistic regression analysis showed that WMH was significantly associated with OAB (OR 1.82, 95% CI 1.11-2.98), after adjustment for clinically important confounders.

CONCLUSIONS

Cerebral WMH volume is associated with OAB, independent of age, sex, body mass index and diabetes mellitus. Geriatr Gerontol Int 2021; 21: 996-1002.

The innervation of the bladder, the pelvic floor, and emotion: A review

The innervation of the pelvic region is complex and includes extensive neurologic pathways. The higher centres' organisation determining the pelvic floor and organs' function remains a challenge understanding the physiological and pain mechanisms. Psychological and emotional factors have a profound influence on the pelvic floor and organ dysfunction such as LUTS. LUTS are associated with stress, depression, and anxiety. Neuroception is a subconscious neuronal system for detecting threats and safety and might explain the permanent disturbance of higher brain centres maintaining functional urological and gastrointestinal disorders and sphincter dysfunction.

Brain functional connectivity during storage based on resting state functional magnetic resonance imaging with synchronous urodynamic testing in healthy volunteers

The aim of the study was to elucidate the correlation between spatially distinct brain areas with a full bladder from the perspective of functional connectivity using resting-state functional magnetic resonance imaging (rs-fMRI) with simultaneous urodynamic testing in healthy volunteers. The brain regions with full and empty bladders were reported via rs-fMRI using a 3 T magnetic resonance system. Then, we identified brain regions that are activated during bladder filling by calculating the amplitude of low-frequency fluctuation (ALFF) values using brain imaging software (DPABI and SPM8) and empirically derived six regions of interest (ROI) from analysis of activation were used as seeds for resting-state functional connectivity (rs-FC) analysis with the rest of the brain to examine differences in the two conditions. Statistical analysis was performed with a paired t-test and statistical significance was defined as a P < 0.01. Twenty-two healthy volunteers (11 men and 11 women) 35-64 years of age were enrolled. The rs-fMRI scans of 22 healthy volunteers were analyzed. After motion correction, two subjects were excluded. Meaningful data were obtained on 20 of these subjects. Compared with an empty bladder, functional connection enhancement was noted mainly in the right inferior orbitofrontal cortex and bilateral calcarine gyrus, the left lingual gyrus, left fusiform gyrus, left superior occipital gyrus, right insula, right inferior temporal gyrus, superior parietal lobe, left insula, right lingual gyrus, right fusiform gyrus, left parahippocampal gyrus, right inferior temporal gyrus, superior parietal lobe, left calcarine gyrus, bilateral lingual gyrus, prefrontal cortex, including the middle frontal gyrus and superior frontal gyrus, the right middle temporal gyrus, bilateral posterior cingulate cortex, and right precuneus. The decrease in functional connection was mainly located in the right inferior orbitofrontal cortex, prefrontal cortex, including the superior frontal gyrus, orbitofrontal cortex, and anterior cingulate cortex, the left inferior orbitofrontal cortex, right insula, middle occipital gyrus, angular gyrus, inferior frontal gyrus, right insula, middle temporal gyrus, inferior parietal lobe, middle occipital gyrus, supplementary motor area, superior frontal gyrus, left insula, bilateral posterior cingulate cortex, bilateral precuneus, middle occipital gyrus, and right middle temporal lobe. There were significant changes in the functional connectivity of the brain between full and empty bladders in healthy volunteers, which suggests that the central neural processes involved in storage needs brain areas with integrated control. These findings are strong evidence for physicians to consider brain responses in urine storage and offer the provision of some normative data.

Considering non-bladder aetiologies of overactive bladder: a functional neuroimaging study

OBJECTIVES

To better understand the neuropathophysiology of overactive bladder (OAB) in women by characterising supraspinal activity in response to bladder distention and cold stimulation.

SUBJECTS/PATIENTS AND METHODS

We recruited 24 female participants, 12 with OAB (median [interquartile range, IQR] age 40 [32-42] years) and 12 healthy controls (HCs) without lower urinary tract (LUT) symptoms (median [IQR] age 34 [28-44] years), and assessed LUT and cognitive function through neuro-urological examination, 3-day bladder diary, urodynamic investigation, and questionnaires. Functional magnetic resonance (MR) imaging using a 3-T scanner was performed in all participants during automated, repetitive bladder filling and draining (block design) with 100 mL body temperature (37 °C) saline using a MR-compatible and MR-synchronised infusion-drainage device until strong desire to void (HIGH-FILLING/DRAINING) and bladder filling with cold saline (4 °C, i.e. COLD). Whole-brain and region-of-interest analyses were conducted using Statistical Parametric Mapping, version 12.

RESULTS

Significant between-group differences were found for 3-day bladder diary variables (i.e. voiding frequency/24 h, P < 0.001; voided volume/void, P = 0.04; and urinary incontinence [UI] episodes/24 h, P = 0.007), questionnaire scores (International Consultation on Incontinence Questionnaire-Female LUT symptoms [overall, filling, and UI scores, all P < 0.001]; the Overactive Bladder Questionnaire short form [symptoms and quality-of-life scores, both P < 0.001]; the Hospital Anxiety and Depression Scale [anxiety P = 0.004 and depression P = 0.003 scores]), as well as urodynamic variables (strong desire to void, P = 0.02; maximum cystometric capacity, P = 0.007; and presence of detrusor overactivity, P = 0.002). Age, weight and cognitive function (i.e. Mini-Mental State Examination, P = 1.0) were similar between groups (P > 0.05). In patients with OAB, the HIGH task elicited activity in the superior temporal gyrus, ventrolateral prefrontal cortex (VLPFC), and mid-cingulate cortex; and the COLD task elicited activity in the VLPFC, cerebellum, and basal ganglia. Compared to HCs, patients with OAB showed significantly stronger cerebellar activity during HIGH-FILLING and significantly less activity in the insula and VLPFC during HIGH-DRAINING.

CONCLUSIONS

The present findings suggest a sensory processing and modulation deficiency in our OAB group, probably as part of their underlying pathophysiology, as they lacked activity in essential sensory processing areas, such as the insula. Instead, accessory areas, such as the cerebellum, showed significantly stronger activation compared to HCs, presumably supporting pelvic-floor motor activity to prevent UI. The novel findings of the present study provide physiological evidence of the necessity to consider non-bladder aetiologies of bladder symptoms.

Overactive Bladder in Frail Older Adults

Overactive bladder (OAB) and frailty are multidimensional syndromes, and the prevalence of both increases with age. Little evidence exists for a direct association between OAB and frailty, but urinary urgency may well be a precursor of frailty in older people. Frail older adults are no less deserving of treatment than fit older adults, and lifestyle, behavioral, and pharmacological interventions remain the primary options for treatment, with some evidence for efficacy. Data on onabotulinumtoxinA therapy or percutaneous tibial nerve stimulation in frail older adults are sparse. Frail older adults are often excluded from drug trials, but evidence is accumulating that antimuscarinics and, to a lesser extent, beta-adrenergic agonists are safe, well-tolerated, and effective in older adults. Cognitive impairment associated with frailty should not be used as justification for avoiding the use of antimuscarinics. More studies are required to better understand the association between OAB and frailty, as both are associated with poor outcomes and may be amenable to intervention. Drug trials for OAB treatments should be encouraged to include frail older adults, as this population is highly affected yet often excluded.

Regional brain atrophy in overactive bladder syndrome: a voxel based morphometry study

OBJECTIVES

To investigate whether patients with overactive bladder syndrome (OAB) have brain volume changes using voxel-based morphometry (VBM) and correlations with clinical tests.

METHODS

With institutional review board approval and after obtaining written informed consent, structural magnetic resonance imaging data were prospectively acquired in 28 patients and 28 control subjects. OAB symptoms were assessed using the OAB symptom score (OABSS) scale. The gray matter volume (GMV) of each voxel was compared between the two groups while controlling for the effects of age, sex, and education level. Correlation analysis was performed to identify correlations between abnormal GMV regions and OABSS scores in patients. Multiple comparisons were corrected using a false discovery rate (FDR) method.

RESULTS

Patients with OAB exhibited a GMV reduction in the right cerebellum, bilateral hippocampus, left insula, right superior temporal gyrus, left anterior cingulate gyrus, bilateral caudate nucleus and right middle frontal gyrus. Furthermore, there was a significant negative correlation between the local GMV of the right cerebellar hemisphere and OABSS score.

CONCLUSIONS

Patients with OAB have abnormal GMV in brain regions localized within the brain-bladder control network. It deepens our understanding of the structural changes in the brain area of the network. The patterns of structural reorganization in patients with OAB may provide useful information in the neuropathological mechanisms of the OAB.

Impact of Intravesical Cold Sensation on Functional Network Connectivity Estimated Using ICA at Rest & During Interoceptive Task

Afferent nerves that carry interoceptive signals from the viscera to the brain include Aδ and C-fibers. Previously, we examined the effects of detrusor distention (conveyed mainly by Aδ fibers) on the static functional network connectivity (FNC) of the brain using independent component analysis (ICA) of fMRI time series. In the present study, we investigate the impact of intravesical cold sensation (thought to be conveyed by C-fibers) on brain FNC using similar ICA approach. Thirteen healthy women were scanned on a 3.0T MRI scanner during a resting state scan and an intravesical cold sensation task fMRI. High dimensional ICA (n = 75) were used to decompose the fMRI data into several intrinsic connectivity networks (ICNs) including the default-mode (DMN), subcortical (SCN; amygdala, thalamus), salience (SN), central executive (CEN), sensorimotor (SMN), and cerebellar/brainstem (CBN) networks. Results demonstrate significant FNC differences in several ICN pairs primarily between the SCN and cognitive networks such as CEN, as well as between SN and CBN and DMN when intravesical cold water condition was compared to rest (FDR-corrected p-value of 0.05). Significant increases in FNC between CBN and between SMN were also observed during interoceptive condition. The results indicate significant impact of Aδ and C-fiber-originated interoceptive signals on the brain connectivity when compared to the baseline rest.

Serotonin in the rat prefrontal cortex controls the micturition reflex through 5-hydroxytryptamine 2A and 5-hydroxytryptamine 7 receptors

Objectives

To identify the types of serotonin (5‐hydroxytryptamine) receptors of the prefrontal cortex related to the micturition reflex.

Methods

Female Sprague–Dawley rats and a microinjection method were used for this study. Stainless steel guide cannulas were implanted bilaterally into the prefrontal cortex, and a polyethylene catheter was inserted into the bladder. Cystometric parameters (intercontraction interval and maximum voiding pressure) were measured before and after injection of any one of six specific antagonists of 5‐hydroxytriptamine receptors (5‐hydroxytryptamine 1A, 5‐hydroxytryptamine 2A, 5‐hydroxytryptamine 2C, 5‐hydroxytryptamine 3, 5‐hydroxytryptamine 4 and 5‐hydroxytryptamine 7) into the prefrontal cortex. The prefrontal cortex was divided into two regions, namely the prelimbic cortex and the infralimbic cortex. The experiments were carried out in conscious and free‐moving rats.

Results

The intercontraction interval value increased significantly after injection of the 5‐hydroxytriptamine 2A receptor antagonist, MDL11939, into the prelimbic cortex of the rat prefrontal cortex (7.68 ± 1.28 vs 9.02 ± 1.41 min, P < 0.05), whereas the intercontraction interval value decreased significantly after injection of the 5‐hydroxytriptamine 7 antagonist SB269970 into the prelimbic cortex (9.42 ± 0.39 vs 8.14 ± 0.71 min, P < 0.05). The intercontraction interval was unaffected by injection of either of these two antagonists into the infralimbic cortex. The other four antagonists (5‐hydroxytryptamine 1A, 5‐hydroxytryptamine 2C, 5‐hydroxytryptamine 3 and 5‐hydroxytryptamine 4) had no effect on the intercontraction interval after injection into the prelimbic cortex and the infralimbic cortex. The maximum voiding pressure was unaffected by injection of any one of the six 5‐hydroxytriptamine antagonists into the prelimbic cortex and infralimbic cortex.

Conclusions

In the rat prefrontal cortex5‐hydroxytryptamine 2A receptors excite the micturition reflex, whereas 5‐hydroxytryptamine 7 receptors inhibit this reflex.

Clinical Impact of Deep Brain Stimulation on the Autonomic System in Patients with Parkinson's Disease

Background

The role of deep brain stimulation (DBS) in the management of motor symptoms in patients with Parkinson's disease is well defined. However, it is becoming increasingly clear that DBS can either improve or worsen a number of non-motor phenomena.

Objectives

We examined the published literature to better understand the effects on autonomic symptoms following DBS of the subthalamic nucleus and the globus pallidus interna.

Methods

We conducted a PubMed search of studies regarding the effects of DBS on the autonomic system published from January 2001. We searched for the following terms and their combinations: Parkinson's disease, deep brain stimulation, subthalamic nucleus, globus pallidus interna, autonomic dysfunction.

Results

Most studies reported in the literature focus on DBS targeting the subthalamic nucleus, with particular emphasis on favorable outcomes regarding gastrointestinal function and bladder control. However, the emergence or worsening of autonomic symptoms in subgroups of patients has also been documented. More controversial is the effect of stimulation on the cardiovascular, pulmonary, and thermo-regulatory systems as well as sexual functioning. Data regarding the influence of DBS on the autonomic system when the target is the globus pallidus interna is less forthcoming, with target selection varying according to centre and clinical indication.

Conclusions

DBS appears to affect the autonomic nervous system, with varying degrees of influence, which may or may not be clinically beneficial for the patient. A better understanding of these effects could help personalize stimulation for individual patients with autonomic disorders and/or avoid autonomic symptoms in susceptible patients.

Regions of the brain activated in bladder filling vs rectal distention in healthy adults: A meta-analysis of neuroimaging studies

AIMS

Adults with pelvic floor disorders commonly present with overlapping bladder and bowel symptoms; however, the relationship between urinary and defecatory dysfunction is not well understood. Our aim was to compare and determine if overlapping brain regions are activated during bladder filling and rectal distention in healthy adults.

METHODS

We conducted separate Pubmed searches for neuroimaging studies investigating the effects of rectal distention and bladder filling on brain activation in healthy subjects. Coordinates of activated regions were extracted with cluster-level threshold P < .05 and compared using the activation likelihood estimate approach. Results from the various studies were pooled and a contrast analysis was performed to identify any common areas of activation between bladder filling and rectal distension.

RESULTS

We identified 96 foci of activation from 14 neuroimaging studies on bladder filling and 182 foci from 17 studies on rectal distension in healthy adults. Regions activated during bladder filling included right insula, right and left thalamus, and right periaqueductal grey. Regions activated during rectal distention included right and left insula, right and left thalamus, left postcentral gyrus, and right inferior parietal lobule. Contrast analysis revealed common activation of the right insula with both rectal distention and bladder filling.

CONCLUSION

Bladder filling and rectal distention activate several separate areas of the brain involved in sensory processing in healthy adults. The common activation of the insula, the region responsible for interoception, in these two conditions may offer an explanation for the coexistence of bladder and defecatory symptoms in pelvic floor disorders.

Is the strong desire to void a source of diverted attention in healthy adult volunteers?

AIMS

The strong desire to void (SDV) induces changes in both cognition and gait. This may be due to the sensation of urinary urge acting as a source of diverted attention. This exploratory study examined the influence of SDV and a standardized distracting task on the performance of two measures of cognition, a simple reaction time (SRT) test and the trail making B test (TMT-B).

METHODS

18 volunteers, 8 male and 10 female, without lower urinary tract symptoms (LUTS) (mean age: 20.5, range: 20-47), performed a test of SRT and the TMT-B under three conditions; undistracted with an empty bladder, while experiencing SDV, and when performing a simultaneous distracting task, the auditory n back test.

RESULTS

A statistically significant increase in SRT was found when experiencing SDV and when distracted compared with the undistracted, bladder empty condition. The time taken to compete the TMT-B significantly increased with distraction but was not affected by SDV.

CONCLUSION

SDV induced a similar but smaller change in reaction time when compared with a distracting task, suggesting that SDV may act as a source of diverted attention in continent, healthy volunteers.

Association of autonomic symptoms with presynaptic striatal dopamine depletion in drug-naive Parkinson's disease: An analysis of the PPMI data

While the involvement of the central and peripheral autonomic networks is thought to play an integral role in the development of autonomic symptoms in Parkinson's disease (PD), there is little evidence for an association between autonomic symptoms and striatal dopaminergic depletion. We compared dopamine transporter activity in striatal subregions with various autonomic symptoms covered by the SCOPA-AUT domains including gastrointestinal, urinary, cardiovascular, thermoregulatory, pupillomotor, and sexual symptoms in 418 untreated patients with PD. We found evidence for a dopaminergic association with only urinary symptoms. Moreover, dopaminergic denervation in the putamen but not in the caudate may underlie these symptoms.

The association between lower urinary tract symptoms and falls: Forming a theoretical model for a research agenda

BACKGROUND

There is a well-recognised association between falls and lower urinary tract symptoms (LUTS) in older adults, with estimates of odd ratios for falls in the presence of LUTS ranging between 1.5 and 2.3. Falls and LUTS are both highly prevalent among older people and both are markers of frailty, with significant associated morbidity, mortality, and healthcare resource cost. This association is not well examined or explained in the literature.

AIMS

We aimed to outline current knowledge of the association between falls and lower urinary tract symptoms and suggest a research program to further investigate this.

MATERIALS AND METHODS

A consensus conference of experts in the field was convened to review the current literature and brainstorm potential future investigative avenues.

RESULTS AND DISCUSSION

Despite the recognition of this association, there has been little research to examine its potential causes, and no intervention trial has established if reducing LUTS or urinary incontinence can reduce the risk of falls. The commonly held assumption that urgency causes falls through rushing to the toilet is likely incorrect. Falls and LUTS are both symptoms of frailty and have many common causes. Gait, balance, and continence are all processes requiring cognitive input, and the concept of dual tasking may be a further link.

CONCLUSION

The significant association between lower urinary tract symptoms and falls is currently unexplained, and further research into the potential causes of this association is needed.

The use of imaging techniques in understanding lower urinary tract (dys)function

The ability to store urine in the bladder and to void at an appropriate time depends on several complex mechanisms in the lower urinary tract (LUT) and its neural control. Normal LUT function requires coordination of the urinary bladder, urethra, pelvic floor, efferent and afferent neurons and specific spinal cord and brain areas. These structures can be visualised using different imaging modalities, such as ultrasound, X-ray and magnetic resonance imaging. The supraspinal neural control of the LUT can be studied using functional brain imaging. During the last two decades, the many technological improvements of these imaging techniques have increased our knowledge of voiding dysfunction. Here, we review the different imaging modalities of the LUT and its neural control and discuss their importance for diagnosing and understanding voiding dysfunction.

Brain activation in response to bladder filling in healthy adults: An activation likelihood estimation meta-analysis of neuroimaging studies

AIMS

Recent studies have used different neuroimaging techniques and identified various brain regions that are activated during bladder filling. However, there is a lack of consensus regarding which of these brain regions regulate the process of urine storage. The aim of this meta-analysis is to identify brain regions that are commonly activated during bladder filling in healthy adults across different studies.

METHODS

PubMed was searched for neuroimaging studies investigating the effects of bladder filling on regional brain activation. Studies were excluded if they did not report brain activation differences from whole-brain group analysis by comparing the state of bladder filling with the state of bladder rest. The current version of the activation likelihood estimation (ALE) approach was used for meta-analysis.

RESULTS

We identified 14 neuroimaging studies examining brain activation in response to experimental bladder filling in 181 healthy subjects, which reported 89 foci for ALE analysis. The meta-analysis revealed significant activation in multiple brain regions including thalamus (bilaterally), right insula, cerebellum, and brainstem (bilaterally).

CONCLUSIONS

Several key brain regions involved in sensory processing are commonly activated during bladder filling in healthy adults across different studies. Neurourol. Urodynam. 36:960-965, 2017. © 2016 Wiley Periodicals, Inc.

Pathophysiological and Therapeutic Considerations for Non-Neurogenic Lower Urinary Tract Dysfunction in Children

Non-neurogenic lower urinary tract dysfunction (LUTD) in children is very common in clinical practice and is important as an underlying cause of lower urinary tract symptoms, urinary tract infection and vesicoureteral reflux in affected children. LUTD in children is caused by multiple factors and might be related with a delay in functional maturation of the lower urinary tract. Behavioral and psychological problems often co-exist in children with LUTD and bowel dysfunction. Recent findings in functional brain imaging suggest that bladder bowel dysfunction and behavioral and psychiatric disorders in children might share common pathophysiological factors in the brain. Children with suspected LUTD should be evaluated properly by detailed history taking, validated questionnaire on voiding and defecation, voiding and bowel diary, urinalysis, screening ultrasound, uroflowmetry and post-void residual measurement. Invasive urodynamic study such as videourodynamics should be reserved for children in whom standard treatment fails. Initial treatment of non-neurogenic LUTD is standard urotherapy comprising education of the child and family, regular optimal voiding regimens and bowel programs. Pelvic floor muscle awareness, biofeedback and neuromodulation can be used as a supplementary purpose. Antimuscarinics and α-blockers are safely used for overactive bladder and dysfunctional voiding, respectively. For refractory cases, botulinum toxin A injection is a viable treatment option. Prudent use of urotherapy and pharmacotherapy for non-neurogenic LUTD should have a better chance to cure various problems and improve self-esteem and quality of life in affected children.

Urinary dysfunction and motor symptoms in untreated Parkinson's disease

OBJECTIVES

The aim of the present study was to determine the associations of motor symptoms in untreated Parkinson's disease (PD) with urinary dysfunction. We therefore examined the association between the overactive bladder symptom score (OABSS) and Unified Parkinson's Disease Rating Scale (UPDRS).

PATIENTS AND METHODS

Thirty-one untreated PD patients without dementia (12 men and 19 women with a mean age of 72.0±6.7years) were included in this study. Their urinary tract dysfunctions were rated using the OABSS. The motor symptoms of all patients were also assessed using UPDRS.

RESULTS

OABSS had significant correlations with UPDRS motor score (Spearman's rho=0.39, p=0.03) and akinetic-rigid score (Spearman's rho=0.47, p=0.01). However, OABSS showed no significant correlation with tremor score, age, or duration of PD.

CONCLUSIONS

Higher OABSS was consistently associated with increase in severity of motor disorders, especially akinetic-rigid score, in the study participants.

Differences in neurotransmitter systems of ventrolateral periaqueductal gray between the micturition reflex and nociceptive regulation: An in vivo microdialysis study

OBJECTIVES

To elucidate the possible involvement of glutamate and serotonin (5-hydroxytryptamine) neurons in the ventrolateral midbrain periaqueductal gray during noxious stimulation.

METHODS

The study was carried out by evoking a noxious stimulation by acetic acid in an animal model of cystitis. Changes in glutamate and 5-hydroxytryptamine in the periaqueductal gray during the micturition reflex and acetic acid-induced cystitis were determined using in vivo microdialysis combined with cystometry in rats.

RESULTS

Extracellular glutamate levels slightly, but significantly, increased during the micturition reflex induced by saline infusion into the bladder. Intravesical infusion of acetic acid facilitated the micturition reflex characterized by increases in voiding pressure and decreases in the intercontraction interval. Glutamate levels were markedly increased by acetic acid, and this enhancement was sustained for at least 3 h. 5-Hydroxytryptamine levels, which were not altered during the micturition reflex, were increased after intravesical infusion of acetic acid.

CONCLUSION

The results suggest that periaqueductal gray glutamate and 5-hydroxytryptamine neurons differentially participate in the modulation of both nociception and the micturition reflex. Furthermore, periaqueductal gray 5-hydroxytryptamine levels appear to reflect the nociceptive stimuli.

Urinary Retention Associated with Stroke

Patients often exhibit urinary retention following a stroke. Various neuropathological and animal studies have implicated the medulla oblongata, pons, limbic system, frontal lobe as areas responsible for micturition control, although the exact area responsible for urinary retention after stroke is not clear. The purpose of this study was to identify the stroke area responsible for urinary retention by localizing the areas where strokes occur. We assessed 110 patients with cerebral infarction and 27 patients with cerebral hemorrhage (78 men, 59 women; mean age, 73.0 years) who had been admitted to our hospital between October, 2012 and September, 2013. We used computed tomography (CT) and magnetic resonance imaging (MRI) to investigate the stroke location, and evaluated whether post-stroke urinary retention occurred. Twelve (8.8%) of the 137 patients (7 men, 5 women; mean age, 78.8 years) exhibited urinary retention after a stroke. Stroke occurred in the right/left dominant hemisphere in 7 patients; nondominant hemisphere in 1; cerebellum in 3; and brainstem in 1. Strokes in the dominant hemisphere were associated with urinary retention (P = 0.0314), particularly in the area of the insula (P < 0.01). We concluded that stroke affecting the insula of the dominant hemisphere tends to cause urinary retention.

Neural control of micturition in humans: a working model

Results from functional brain scanning have shown that neural control of the bladder involves many different regions. Yet, many aspects of this complex system can be simplified to a working model in which a few forebrain circuits, acting mainly on the midbrain periaqueductal grey (PAG), advance or delay the triggering of the voiding reflex and generate bladder sensations according to the volume of urine in the bladder, the safety of voiding and the emotional and social propriety of doing so. Understanding these circuits seems to offer a route to treatment of conditions, such as urgency incontinence or overactive bladder, in patients without overt neurological disease. Two of these circuits include, respectively, the medial prefrontal cortex and the parahippocampal complex, as well as the PAG. These circuits belong to a well-known network that is active at rest and deactivated when attention is required. Another circuit, comprising the insula and the midcingulate or dorsal anterior cingulate cortex, is activated by bladder filling and belongs to a salience network that generates sensations such as the desire to void. Behavioural treatments of urgency incontinence lead to changes in brain function that support the working model and suggest the mechanism of this type of treatment.

Role of the Anterior Cingulate Cortex in the Control of Micturition Reflex in a Rat Model of Parkinson's Disease

PURPOSE

In the current study we examined dynamic changes in neural activity of the anterior cingulate cortex and the midbrain periaqueductal gray during the micturition reflex in a Parkinson's disease model as well as the effects of direct stimulation of the anterior cingulate cortex on the micturition reflex.

MATERIALS AND METHODS

Electrodes were inserted in the anterior cingulate cortex or the periaqueductal gray. The effects of intravenous administration of the adenosine A2A receptor antagonist ZM24138 on pelvic nerve evoked field potentials were examined. The effect of electrical stimulation of the anterior cingulate cortex was also examined.

RESULTS

Rats with Parkinson's disease showed bladder overactivity as evidenced by a significant decrease in the intercontraction interval compared with sham operated rats. Intravenous administration of ZM24138 increased the intercontraction interval in both groups with the inhibitory effects greater in rats with Parkinson's disease. It dose dependently increased the amplitude of evoked potentials in the anterior cingulate cortex of rats with Parkinson's disease but not in sham operated rats. Intravenous administration of ZM24138 decreased evoked potential amplitude in the periaqueductal gray of both groups with the inhibitory effects greater in Parkinson's disease vs sham operated rats. Electrical stimulation of the anterior cingulate cortex significantly increased the intercontraction interval.

CONCLUSIONS

These results suggest that anterior cingulate cortex neurons have an inhibitory role in bladder control. Neural activity in the anterior cingulate cortex was significantly increased along with suppression of bladder overactivity after ZM241385 administration in the Parkinson's disease model and the stimulation of the anterior cingulate cortex inhibited the micturition reflex. Understanding the roles of the anterior cingulate cortex in the modulation of micturition could provide further insights into the pathophysiology of overactive bladder.

(18F)FDG-PET brain imaging during the micturition cycle in rats detects regions involved in bladder afferent signalling

BACKGROUND

This feasibility study established an experimental protocol to evaluate brain activation patterns using fluorodeoxyglucose positron emission tomography ((18F)FDG-PET) during volume-induced voiding and isovolumetric bladder contractions in rats.

METHODS

Female Sprague-Dawley rats were anaesthetized with urethane and underwent either volume-induced voiding cystometry or isovolumetric cystometry and simultaneous functional PET brain imaging after injection of (18F)FDG in the tail vein. Brain glucose metabolism in both groups was compared to their respective control conditions (empty bladder). Relative glucose metabolism images were anatomically standardized to Paxinos space and analysed voxel-wise using Statistical Parametric Mapping 12 (SPM12).

RESULTS

During volume-induced voiding, glucose hypermetabolism was observed in the insular cortex while uptake was decreased in a cerebellar cluster and the dorsal midbrain. Relative glucose metabolism during isovolumetric bladder contractions increased in the insular and cingulate cortices and decreased in the cerebellum.

CONCLUSIONS

Our findings demonstrate that volume-induced voiding as well as isovolumetric bladder contractions in rats provokes changes in brain metabolism, including activation of the insular and cingulate cortices, which is consistent with their role in the mapping of bladder afferent activity. These findings are in line with human studies. Our results provide a basis for further research into the brain control of the lower urinary tract in small laboratory animals.

Differential functional brain network connectivity during visceral interoception as revealed by independent component analysis of fMRI TIME-series

Influential theories of brain-viscera interactions propose a central role for interoception in basic motivational and affective feeling states. Recent neuroimaging studies have underlined the insula, anterior cingulate, and ventral prefrontal cortices as the neural correlates of interoception. However, the relationships between these distributed brain regions remain unclear. In this study, we used spatial independent component analysis (ICA) and functional network connectivity (FNC) approaches to investigate time course correlations across the brain regions during visceral interoception. Functional magnetic resonance imaging (fMRI) was performed in thirteen healthy females who underwent viscerosensory stimulation of bladder as a representative internal organ at different prefill levels, i.e., no prefill, low prefill (100 ml saline), and high prefill (individually adapted to the sensations of persistent strong desire to void), and with different infusion temperatures, i.e., body warm (∼37°C) or ice cold (4-8°C) saline solution. During Increased distention pressure on the viscera, the insula, striatum, anterior cingulate, ventromedial prefrontal cortex, amygdalo-hippocampus, thalamus, brainstem, and cerebellar components showed increased activation. A second group of components encompassing the insula and anterior cingulate, dorsolateral prefrontal and posterior parietal cortices and temporal-parietal junction showed increased activity with innocuous temperature stimulation of bladder mucosa. Significant differences in the FNC were found between the insula and amygdalo-hippocampus, the insula and ventromedial prefrontal cortex, and the ventromedial prefrontal cortex and temporal-parietal junction as the distention pressure on the viscera increased. These results provide new insight into the supraspinal processing of visceral interoception originating from an internal organ.

A novel intracerebral hemorrhage-induced rat model of neurogenic voiding dysfunction: Analysis of lower urinary tract function

Neurogenic lower urinary tract dysfunction (NLUTD) is a major problem in patients with various neurological disorders, and may result in debilitating symptoms and serious complications, including chronic renal failure and recurrent urinary tract infections. Clinically, stroke is associated with voiding dysfunction. However, lower urinary tract function evaluation in an intracerebral hemorrhage (ICH) model has not, to the best of our knowledge, been reported. Therefore, in the present study, lower urinary tract function in ICH-induced rats was investigated and the results were compared with those obtained in normal rats. The effects of ICH on peripheral bladder function and central micturition centers [medial preoptic area, ventrolateral gray, pontaine micturition center and spinal cord (lumbar 4 (L4)-L5)] were also examined. Adult female Sprague-Dawley rats were divided into two groups: Control ICH-induced. Induction of ICH in the hippocampal CA1 region was performed using a stereotaxic frame and type IV collagenase. The effects of ICH on the central micturition centers were investigated by simultaneously determining the extent of neuronal activation (c-Fos) and nerve growth factor (NGF) expression, and assessing voiding function (urodynamically using cystometry). The results revealed that induction of ICH significantly enhanced bladder contraction pressure and time, while simultaneously reducing voiding pressure and time. Furthermore, the c-Fos and NGF expression levels in the neuronal voiding centers were significantly increased in the rats with induced ICH as compared with the control rats. Therefore, this ICH-induced NLUTD rat model may be a more appropriate method to analyze NLUTD in stroke patients than a cerebral infarction model, as the former more accurately reflects the nature of the hemorrhage in the two types of stroke.

Restoring susceptibility induced MRI signal loss in rat brain at 9.4 T: A step towards whole brain functional connectivity imaging

The aural cavity magnetic susceptibility artifact leads to significant echo planar imaging (EPI) signal dropout in rat deep brain that limits acquisition of functional connectivity fcMRI data. In this study, we provide a method that recovers much of the EPI signal in deep brain. Needle puncture introduction of a liquid-phase fluorocarbon into the middle ear allows acquisition of rat fcMRI data without signal dropout. We demonstrate that with seeds chosen from previously unavailable areas, including the amygdala and the insular cortex, we are able to acquire large scale networks, including the limbic system. This tool allows EPI-based neuroscience and pharmaceutical research in rat brain using fcMRI that was previously not feasible.

Bladder dysfunction and quality of life for people with multiple sclerosis

PURPOSE

Bladder dysfunction affects 75% of people with multiple sclerosis (MS). People with MS are reluctant to seek treatment for this distressing symptom. This is the first-known study to explore in depth how bladder dysfunction interferes with quality of life for people with MS.

METHODS

Nineteen individual semi-structured interviews were conducted (M = 8, F = 11). Participants had a definite diagnosis of MS, aged between 37 and 64 years and had at least one bladder dysfunction symptom. The audio-recorded interviews lasted up to 90 min and were transcribed verbatim.

RESULTS

Thematic analysis within NVivo10 yielded two key themes: (1) Disruptions and loss and (2) ways of knowing. "Disruptions and Loss" explores how bladder dysfunction interrupted daily living activities and how this contributed to experiencing loss. "Ways of knowing" portrays the types of knowledge that existed around bladder dysfunction. Participants described using their experiential knowledge to self-manage bladder symptoms without advice from healthcare providers.

CONCLUSIONS

Bladder dysfunction imposes major disruptions on daily life. People with MS attempt to self-manage their bladder symptoms, despite current barriers to navigating existing healthcare infrastructure. Understanding these barriers and the individual strategies employed by people with MS are the first steps in facilitating independent management of bladder dysfunction. Implications for Rehabilitation Each individual's experience of bladder dysfunction is unique. Healthcare professionals must be prepared to discuss all disruptions and losses associated with bladder dysfunction for people with MS. People with MS have a vast range of knowledge in relation to their own bladder symptoms and healthcare professionals need to explore their existing self-management strategies during assessment. People with MS and healthcare professionals need to be educated on the wider health implications relating to bladder dysfunction.

Neural control of the lower urinary tract

This article summarizes anatomical, neurophysiological, pharmacological, and brain imaging studies in humans and animals that have provided insights into the neural circuitry and neurotransmitter mechanisms controlling the lower urinary tract. The functions of the lower urinary tract to store and periodically eliminate urine are regulated by a complex neural control system in the brain, spinal cord, and peripheral autonomic ganglia that coordinates the activity of smooth and striated muscles of the bladder and urethral outlet. The neural control of micturition is organized as a hierarchical system in which spinal storage mechanisms are in turn regulated by circuitry in the rostral brain stem that initiates reflex voiding. Input from the forebrain triggers voluntary voiding by modulating the brain stem circuitry. Many neural circuits controlling the lower urinary tract exhibit switch-like patterns of activity that turn on and off in an all-or-none manner. The major component of the micturition switching circuit is a spinobulbospinal parasympathetic reflex pathway that has essential connections in the periaqueductal gray and pontine micturition center. A computer model of this circuit that mimics the switching functions of the bladder and urethra at the onset of micturition is described. Micturition occurs involuntarily in infants and young children until the age of 3 to 5 years, after which it is regulated voluntarily. Diseases or injuries of the nervous system in adults can cause the re-emergence of involuntary micturition, leading to urinary incontinence. Neuroplasticity underlying these developmental and pathological changes in voiding function is discussed.

Functional imaging of structures involved in neural control of the lower urinary tract

Recent functional brain imaging studies, building on earlier observations, suggest a working model of brain control of the lower urinary tract. It comprises a few cerebral neural circuits that, during the storage phase, act on the midbrain periaqueductal gray to inhibit the long-loop, spinobulbospinal voiding reflex, thus promoting continence. Circuit 1, centered on the medial prefrontal cortex, appears to be concerned with conscious control of both continence and voiding. Circuit 2, centered on the dorsal anterior cingulate (midcingulate) and supplementary motor area, is concerned with emotional aspects of bladder control: desire to void or urgency with concomitant urethral sphincter activation to delay leakage. A subcortical circuit 3 has been less well studied. Circuit 1 is bilateral with a right-sided preference. Scattered studies of the connectivity of the control network suggest that white-matter damage may contribute to urinary incontinence. A few studies confirm that isolated cerebral lesions, if in the medial prefrontal cortex or its connecting pathways, may lead to incontinence. Lower urinary tract dysfunction in other neurologic diseases (normal-pressure hydrocephalus, Parkinson's disease, and multiple systems atrophy) appears consistent with the working model, and even spinal or peripheral lesions have central effects. However, this model omits the contributions of brain regions already observed in some imaging studies and therefore is certainly oversimplified.

Etiology, triggers and neurochemical circuits associated with unexpected, expected, and laboratory-induced panic attacks

Panic disorder (PD) is a severe anxiety disorder that is characterized by recurrent panic attacks (PA), which can be unexpected (uPA, i.e., no clear identifiable trigger) or expected (ePA). Panic typically involves an abrupt feeling of catastrophic fear or distress accompanied by physiological symptoms such as palpitations, racing heart, thermal sensations, and sweating. Recurrent uPA and ePA can also lead to agoraphobia, where subjects with PD avoid situations that were associated with PA. Here we will review recent developments in our understanding of PD, which includes discussions on: symptoms and signs associated with uPA and ePAs; Diagnosis of PD and the new DSM-V; biological etiology such as heritability and gene×environment and gene×hormonal development interactions; comparisons between laboratory and naturally occurring uPAs and ePAs; neurochemical systems that are associated with clinical PAs (e.g. gene associations; targets for triggering or treating PAs), adaptive fear and panic response concepts in the context of new NIH RDoc approach; and finally strengths and weaknesses of translational animal models of adaptive and pathological panic states.

New horizons: urinary incontinence in older people

Urinary incontinence is a common complaint in older people, and is associated with significant impact on the individual, their carers and the wider healthcare system. As the numbers of frail elderly people increase, so will the burden of incontinence. This review examines recent developments in research into the aetiology, physiology, pathology and treatment of urinary incontinence and lower urinary tract symptoms in older people, and explores potential future developments which might reduce or ameliorate both urinary incontinence and its effects on frail older people. These include increasing understanding of the importance of central control of continence, the role of the urothelium as a sensory organ, novel targets for pharmacological treatments and surgical and invasive interventions.

[Micturition and cognition]

PURPOSE

The physiopathology of the voiding and urinary continence was one of the hot topic of research these last few years. Unfortunately, anyone have already found a unique cause which could explain urinary incontinence (urge or stress). The concept of cognitive function highlights new ways of research to show the fundamental role of the cortex and the sub-cortex in these diseases.

METHODS

A comprehensive literature review using Pubmed, Medline, Embase and Cochrane: "cognition, urinary tract, urinary continence, neuroimaging, IRMf, micturition, urge, brain factor and cognitive therapy". In all the articles, 72 really dealt with micturition and cognition.

RESULTS

New imaging techniques allowed to show the relationship between the different brain area involved in the bladder control such as the periaqueductal gray, the hypothalamus, the insula, the anterior cingulated cortex and the prefrontal cortex. These cortical area are equally involved in cognition. An alteration of urinary continence implies a modification of activation of these cortical areas.

CONCLUSION

A better knowledge of the cognitive side of micturition and urinary continence will allow to improve the treatment of their associated diseases.

Central nervous targets for the treatment of bladder dysfunction

BACKGROUND

The functions of the lower urinary tract, to store and periodically release urine, are dependent on the activity of smooth and striated muscles in the urinary bladder, urethra, and external urethral sphincter. This activity is in turn controlled by neural circuits in the brain, spinal cord, and peripheral ganglia.

AIMS

This paper will review recent advances in our understanding of the pathophysiology of voiding disorders, especially focusing on the central nervous system.

METHODS

Various neurotransmitters, including acetylcholine, norepinephrine, dopamine, serotonin, excitatory and inhibitory amino acids, adenosine triphosphate, nitric oxide, and neuropeptides, have been implicated in the neural regulation of the lower urinary tract.

RESULTS

Injuries or diseases of the nervous system, as well as drugs and disorders of the peripheral organs, can produce voiding dysfunctions such as urinary frequency, urgency, or incontinence.

CONCLUSION

We discuss the potential targets in the central nervous system and new modalities for the treatment of voiding dysfunction.

Brain activity during bladder filling and pelvic floor muscle contractions: a study using functional magnetic resonance imaging and synchronous urodynamics

OBJECTIVES

To map the brain activity during bladder filling by functional magnetic resonance imaging using a refined scanning protocol including synchronous urodynamics and pelvic floor muscle contractions.

METHODS

A total of 23 healthy female volunteers (age 20-68 years) were enrolled. Participants were asked to contract their pelvic floor muscles. This was followed by a urodynamic examination consisting of repeated filling cycles. Brain activity was measured by functional magnetic resonance imaging using a 3T magnetic resonance system. Measurements of brain activity consisted of 120 functional scans during pelvic floor contractions and 210 scans during bladder filling. Each functional magnetic resonance imaging scan covered the brain with 35 slices. Statistical analyses used the general linear model and independent component analysis. Areas of activation were visualized using group statistics.

RESULTS

The following main clusters of activation were observed during pelvic floor muscle contractions: medial surface of the frontal lobe (primary motor area), bilaterally; supplementary motor area, bilaterally; and left gyrus precentralis. During bladder filling, activation was detected in the inferior frontal lobe bordering the frontal cingulum, left gyrus parietalis superior, left central area, right insula, brainstem and thalamus with subcortical gray matter nuclei.

CONCLUSIONS

Our work extends an existing functional magnetic resonance imaging protocol for researching the neural control of the lower urinary tract. The present results are consistent with the available literature and agree with the present hypothetical functional model of lower urinary tract neural control.

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.

The micturition switch and its forebrain influences

Dr DeGroat and Wickens has reviewed the central neural mechanisms controlling the lower urinary tract with a major focus on the brain stem circuitry that mediates the switch-like characteristics of micturition, in particular the periaqueductal grey and the pontine micturition centre (de 2012). The review culminates in a computer model of how the brainstem switch operates in animals in which forebrain influences on micturition have been removed by decerebration. In this complementary paper, we review the mechanisms of forebrain involvement in the voluntary control of human micturition and the maintenance of continence with evidence based heavily on the results of functional brain imaging experiments.

Changes in the brain microstructure of children with primary monosymptomatic nocturnal enuresis: a diffusion tensor imaging study

BACKGROUND

Primary monosymptomatic nocturnal enuresis (PMNE) is a common disorder in school-aged children. Previous studies have suggested that a developmental delay might play a role in the pathology of children with PMNE. However, microstructural abnormalities in the brains of these children have not been thoroughly investigated.

METHODOLOGY/PRINCIPAL FINDINGS

In this work, we evaluated structural changes in the brains of children with PMNE using diffusion tensor imaging (DTI). Two groups consisting of 26 children with PMNE and 26 healthy controls were scanned using magnetic resonance DTI. The diffusion parameters of fractional anisotropy (FA) and mean diffusivity (MD) were subjected to whole-brain, voxel-wise group comparisons using statistical parametric mapping (SPM). When compared to healthy subjects, children with PMNE showed both a decrease in FA and an increase in MD in the thalamus. MD also increased in the frontal lobe, the anterior cingulate cortex and the insula; these areas are all involved in controlling micturition. The significant changes seen in the thalamus could affect both urine storage and arousal from sleep.

CONCLUSIONS/SIGNIFICANCE

The microstructure abnormalities were observed in the thalamus, the medial frontal gyrus, the anterior cingulate cortex and the insula, which are involved in micturition control network. This indicates developmental delay in these areas may be the cause of PMNE.

Neuroimaging of the periaqueductal gray: state of the field

This review and meta-analysis aims at summarizing and integrating the human neuroimaging studies that report periaqueductal gray (PAG) involvement; 250 original manuscripts on human neuroimaging of the PAG were identified. A narrative review and meta-analysis using activation likelihood estimates is included. Behaviors covered include pain and pain modulation, anxiety, bladder and bowel function and autonomic regulation. Methods include structural and functional magnetic resonance imaging, functional connectivity measures, diffusion weighted imaging and positron emission tomography. Human neuroimaging studies in healthy and clinical populations largely confirm the animal literature indicating that the PAG is involved in homeostatic regulation of salient functions such as pain, anxiety and autonomic function. Methodological concerns in the current literature, including resolution constraints, imaging artifacts and imprecise neuroanatomical labeling are discussed, and future directions are proposed. A general conclusion is that PAG neuroimaging is a field with enormous potential to translate animal data onto human behaviors, but with some growing pains that can and need to be addressed in order to add to our understanding of the neurobiology of this key region.

Models for sensory neurons of dorsal root ganglia and stress urinary incontinence

AIMS

To discuss (1) animal models for investigating bladder afferent pathways from the spinal cord to the brain and (2) animal models of stress urinary incontinence (SUI) with a special emphasis on functional and histopathological characteristics of each model.

METHODS

Literature review of spinal mechanisms of bladder afferent pathways and animal models of SUI.

RESULTS

Electrophysiological studies in the rat using pelvic nerve stimulation and recording of evoked potentials in the periaqueductal gray (PAG) prove to be a valuable tool to examine spinal mechanisms of bladder afferent pathways. Animal models of SUI in the rat include vaginal distention as simulated birth trauma, pudendal nerve crush or transection, urethral sphincter injury by electrocauterization, transabdominal urethrolysis, periurethral botulinum-A toxin injection, and pubo-urethral ligament transection. Functional and histopathological changes in the continence mechanism after injury are different between models.

CONCLUSIONS

Using animal models for sensory neurons, intrathecal and intravenous administration of certain drugs can be tested whether they affect the bladder afferent pathways from the spinal cord to the PAG. Animal models of SUI can serve as a tool to develop new pharmacologic therapies or periurethral injection therapies using stem cell implants.