Johan Vande Walle

Voiding Disorders in Children

Voiding problems are often not benign self-limiting conditions resulting from delayed acquirement of continence (daytime incontinence) and enuresis (bedwetting), but are a feature of many conditions at the interface between paediatric nephrology and urology. Voiding disorders include a complex group of conditions in children, caused by abnormalities in bladder function and/or diuresis. Bladder dysfunction is a well-known pathogenic/comorbid factor in urinary tract infections, in many CAKUT abnormalities (uropathies), constipation and neurogenic bladder. The prevalence and importance of bladder dysfunction in children with CKD prior to and after transplantation is underestimated. It is associated with hypertension, sleep disturbances, and cognitive dysfunctions. Deficient concentrating capacity as well as circadian rhythm abnormalities of renal function, have been documented in patients with enuresis, but are also an essential characteristic of glomerular as well as tubular renal pathophysiology. Nocturnal enuresis can be subdivided into monosymptomatic enuresis and non-monosymptomatic enuresis (if lower urinary tract symptoms are present. Monosymptomatic nocturnal enuresis in the majority of patients is caused by a mismatch between nocturnal diuresis and functional bladder capacity overnight in the presence of a deficient arousal. Desmopressin is the treatment of choice in patients with nocturnal polyuria and normal bladder volume, whereas the alarm is superior in patients with low functional bladder capacity and low diuresis volume overnight. Despite EBM therapies, up to 1/3 patients remain refractory to the initial therapy, even when combined. This therapy-resistance coincides with a variety of pathophysiologic mechanisms in kidney, bladder and brain, necessitating individualized therapeutic regimens by multidisciplinary teams. Lower urinary tract symptoms, including daytime symptoms indicate an underlying bladder dysfunction, In these patients neurologic disorders, neurogenic bladder and organic abnormalities of the urinary tract should always be excluded, before diagnosing a functional bladder disorder. Daytime symptoms should be treated before starting the nighttime enuresis-problems. They may characterized according the urine flow patternsduring filling phase and emptying phase. The most frequent is overactivity of the detrusor, where anticholinergics are indicated. Dysfunctional voiding might benefit from more complex regimens, with a major role for urotherarpy and biofeedback training.