Bladder reduction surgery accelerates the appearance of spontaneous voiding in neonatal rats

Altered resting-state functional connectivity of insula in children with primary nocturnal enuresis

Objective

Primary nocturnal enuresis (PNE) is a common developmental condition in school-aged children. The objective is to better understand the pathophysiology of PNE by using insula-centered resting-state functional connectivity (rsFC).

Methods

We recruited 66 right-handed participants in our analysis, 33 with PNE and 33 healthy control (HC) children without enuresis matched for gender and age. Functional and structural MRI data were obtained from all the children. Seed-based rsFC was used to examine differences in insular functional connectivity between the PNE and HC groups. Correlation analyses were carried out to explore the relationship between abnormal insula-centered functional connectivity and clinical characteristics in the PNE group.

Results

Compared with HC children, the children with PNE demonstrated decreased left and right insular rsFC with the right medial superior frontal gyrus (SFG). In addition, the bilateral dorsal anterior insula (dAI) seeds also indicated the reduced rsFC with right medial SFG. Furthermore, the right posterior insula (PI) seed showed the weaker rsFC with the right medial SFG, while the left PI seed displayed the weaker rsFC with the right SFG. No statistically significant correlations were detected between aberrant insular rsFC and clinical variables (e.g., micturition desire awakening, bed-wetting frequency, and bladder volume) in results without global signal regression (GSR) in the PNE group. However, before and after setting age as a covariate, significant and positive correlations between bladder volume and the rsFC of the left dAI with right medial SFG and the rsFC of the right PI with right medial SFG were found in results with GSR in the PNE group.

Conclusion

To the best of our knowledge, this study explored the rsFC patterns of the insula in children with PNE for the first time. These results uncovered the abnormal rsFC of the insula with the medial prefrontal cortex without and with GSR in the PNE group, suggesting that dysconnectivity of the salience network (SN)-default mode network (DMN) may involve in the underlying pathophysiology of children with PNE. However, the inconsistent associations between bladder volume and dysconnectivity of the SN-DMN in results without and with GSR need further studies.

Sex differences in neonatal and young adult rat lower urinary tract function caused by bladder reduction

INTRODUCTION

Pediatric urinary incontinence has been proposed as a cause for adult urinary incontinence, yet animal models mimic the findings of overactive bladder more closely than dysfunctional voiding. We used the bladder reduction (BR) model to study the effects of early external urethral sphincter (EUS) dysfunction on the maturation of lower urinary tract function in neonatal and young adult rats of both sexes.

OBJECTIVE

To determine long-term alterations in bladder and EUS function in young adult rats caused by neonatal BR.

MATERIALS AND METHODS

46 Sprague-Dawley rats underwent BR and 52 underwent sham surgery at 1 week of age. At 3, 6, and 9 weeks of life, cystometry was carried out, 8-OH-DPAT (serotonergic receptor agonist) and WAY 100,635 (serotonergic receptor antagonist) were administered intravenously. Pressure threshold (PT), volume threshold (VT), storage tonic AUC, contraction area under the curve (AUC), EUS burst amplitude and burst duration were measured at baseline and after administration of serotonergic agents.

RESULTS

PT increased in 3-week BR females compared with shams (31.1 vs. 22.7 cm H2O, p < 0.01), in conjunction with less efficient EUS emptying, as burst amplitude was suppressed (BR 0.04 vs. sham 0.07 mV, p < 0.05). VT subsequently increased in 9-week BR females compared with shams (0.81 vs. 0.36 mL, p < 0.05). Although 3-week BR males also experienced suppressed burst amplitude (BR 0.17 vs. sham 0.28 mV, p < 0.05), they showed no difference in PT at 3 weeks or VT at 9 weeks compared with sham males. The burst amplitude returned to normal in 6- and 9-week BR animals of both sexes, confirming a spontaneous recovery of EUS function over time. The thresholds for voiding in male rats are not as sensitive to early changes in EUS function compared with female rats. The response to serotonergic agents was identical between BR and sham animals. In the female animals, 8-OH-DPAT increased storage tonic AUC and burst duration, whereas in male animals, 8-OH-DPAT increased contraction AUC, burst amplitude, and burst duration. WAY 100,635 reversed the enhancements of EUS function caused by 8-OH-DPAT.

CONCLUSIONS

BR caused a temporary impairment of EUS emptying at 3 weeks of life, similar to dysfunctional voiding, while serotonergic agonists remained effective at enhancing EUS emptying in BR animals. Although EUS emptying spontaneously improved, the increase in VT in female young adult rats suggests that timely treatment of EUS dysfunction is required to decrease the risk of long-term bladder dysfunction.

Is there still a role for desmopressin in children with primary monosymptomatic nocturnal enuresis?: a focus on safety issues

It has recently became apparent that severe primary monosymptomatic nocturnal enuresis (MNE) has a worse prognosis than generally believed, and may have major consequences on the well-being of the child, thus making treatment mandatory. Desmopressin is one of the most widely prescribed medications for MNE, and in this current opinion article we discuss the safety of desmopressin in children with this condition. Following a US FDA request in December 2007 that the prescribing information for desmopressin nasal spray be updated, desmopressin spray is no longer indicated for the treatment of MNE or for use in patients at risk for hyponatraemia. Multiple reports of hyponatraemia in patients with nocturia (mainly the elderly) led to an increased awareness of the risks associated with desmopressin. While the pathogenesis of hyponatraemia in those over 65 years of age relates more to changing renal water and solute handling, we believe that in the young, overdosing and insufficient fluid restriction are usually the major causes. Hyponatraemia is most frequently reported when desmopressin is administered by nasal spray compared with the tablet formulation. This may simply reflect the fact that for more than 10 years the spray was the only available mode of administration in many countries. However, it may also reflect the higher biodisponibility and/or intraindividual variability of pharmacokinetics of the spray compared with the tablet. There are few serious adverse events reported for the melt formulation (oral lyophilisate), but as it has only recently become available on the market, it would be premature to conclude that it has a better safety profile. We believe that desmopressin in all formulations has a good safety profile in children with MNE, provided that treatment is properly prescribed and monitored; improving the training of doctors and patients in the dose-response kinetics of the drug, teaching appropriate restriction of fluid intake and by encouraging the use of desmopressin within a narrow dose range (10-20 microg spray, 120-240 microg melt and 200-400 microg tablet) when used in primary-care settings. Titrating higher doses in therapy-resistant patients should probably be carried out in a specialized enuresis centre, and only after documenting adequate morning urinary diluting capacity. In summary, the risk of hyponatraemia is exacerbated by misuse of the drug rather than an inherent danger associated with the drug, which in our opinion should be addressed with better education rather than withdrawal of a medication that has the potential to benefit children with nocturnal enuresis.

Achieving urinary continence in children

Achievement of urinary continence is an important developmental step that most children attain with the assistance of their parents and caregivers. Debate continues as to the best time to toilet train; in some Asian and African cultures children are trained as infants, while training at age 2-3 years is more typical in Western cultures. Infant voiding is not merely a spinal reflex, as the sensation of bladder filling is relayed to the brain. However, the ability of the brain to inhibit bladder contractions, and to achieve coordinated bladder contraction with sphincter relaxation, matures over time. While there is a concern that later toilet training may be responsible for an increase in urinary incontinence in children, no controlled studies on early versus late toilet training exist to evaluate this hypothesis. A number of medical conditions such as spina bifida, posterior urethral valves, cerebral palsy and autism can cause incontinence and difficulties in toilet training. The decision to start toilet training a child should take into account both the parents' expectation of how independent the child will be in terms of toileting, and the child's developmental readiness, so that a realistic time course for toilet training can be implemented.