The annual congress of the International Children’s Continence Society took place in Gdansk, Poland from the 12th to the 14th of September. More than 180 paediatricians, paediatric urologists, paediatric nephrologists, and urotherapists were gathered to present and discuss the latest research in the field of childhood incontinence. Nocturnal enuresis traditionally occupies a large part of the scientific program. This year, too, a number of high-quality studies concerning bedwetting were discussed. Biomarkers as predictors of treatment and sleep as pathophysiological factor in nocturnal enuresis were this year’s areas of research which attracted the most attention. A selection of the most important studies discussed.
A prospective study from Croatia (1) evaluated the first morning urine osmolality as a predictor of desmopressin response. It was conducted on a rather large sample of patients (332). The authors provided data showing poor response to desmopressin in children who shared higher urine osmolalities. The hypothesis is that children who already maximally concentrate their urine during the night may not benefit from desmopressin, since further reduction in urine volumes is not possible. The authors conclude that other treatment modalities ought to be applied to these children. Measuring the first morning urine osmolality is rather easy and a non-invasive method of assessing the renal concentrating capacity. It seems a promising predictor of treatment efficacy. However, as the parameters show significant variation even within an individual child, its role as a predictor of treatment response needs further studying.
In the same line of research, a Japanese group (2) assessed AQP2 as a possible predictor of treatment response. AQP2 is the arginine-vasopressin-regulated water channel in the renal tubuli, which is largely responsible for water conservation and thus urine concentration. The authors assessed the AQP2 concentration in the first morning urine of 52 children with evident nocturnal polyuria. They found that children with lower AQP2 levels in their urine were exhibiting better response to desmopressin over a period of 6 months. The hypothesis is that these children with lower AQP2 levels share lower arginine vasopressin levels overnight and thus a higher urine output due to the excretion of excess water. These children are thought to be good candidates for desmopressin treatment. The fact that children with high AQP2 levels do not respond to desmopressin indicates that factors beyond the renal water handling are of importance in these children. This hypothesis has previously been suggested by a number of studies showing excess sodium and osmotic excretion in these children.
We cannot discuss nocturnal enuresis without discussing sleep and its characteristics. Sleep is not easy to assess or measure in children. In addition, sleep physiology is particularly complex. This makes any conclusions on the role of sleep in enuresis difficult. However, new tools such as smart phones, activity trackers, and smart watches are emerging. These tools can be used to evaluate sleep parameters in a less invasive way than the golden standard of sleep evaluation, which is polysomnography. A German team of researchers (3) employed such a device to assess not only sleep quality, but also daytime activity in children with nocturnal enuresis. This is an ongoing study; as a result of this, the researchers provided us with preliminary data measured by actigraphy. This data showed no significant differences in sleep quality between children with bedwetting and a matched control group. Simultaneously, enuretic children appeared more active during daytime — but this may relate to comorbid psychiatric disorders such as ADHD. We are looking forward to discussing the final results of the study during the next ICCS meeting.
The same group of researchers presented perhaps the most discussed paper (4) of the enuresis session, in which olfactory performance in children with incontinence was evaluated. This was the very first study that discussed the ability of children with incontinence to detect and differentiate smells. Interestingly, olfactory dysfunction occurs in diseases such as Alzheimer and Parkinson as well as ADHD and autism. Since central nervous system functions have also to do with incontinence, the aim of the study was to examine olfactory functions as a potential neurobiological correlate of incontinence. The authors found that children with incontinence including nocturnal enuresis have a lower olfactory threshold. As olfactory function may reflect frontal lobe function, it remains to be elucidated whether these findings indicate frontal lobe dysfunction in children with incontinence.
A lot of attention has been drawn to rapid maxillary expansion as a treatment modality for nocturnal enuresis. Case series and uncontrolled studies have previously indicated that a number of children undergoing expansion for orthodontic purposes may experience improvement in bedwetting. As rapid maxillary expansion widens the palate, it increases airway size and thus may improve breathing during sleep; the rationale behind bedwetting. A Swedish group of researchers (5) performed a placebo-controlled study on rapid maxillary expansion in children who are not in need of orthodontic treatment. The group found no effect of the intervention on the frequency of enuresis episodes. The discussion is whether such a treatment modality only improves bedwetting in children with small palates who need orthodontic treatment.
The next ICCS meeting is scheduled to take place in Dubai in October 2020.
