THE PATHOPHYSIOLOGY OF ENURESIS IN CHILDREN AND YOUNG-ADULTS

Bedwetting is the most common urologic complaint among children. Wetti ng frequency at age 7 years varies from 5% to 15%. Treatment has been multimodal: drugs to depress bladder activity, increase urethral resis tance, or modulate sleep; electrophysiologic treatment; and, recently, urine production modulation. All of these approaches reflect a lack o f sufficient knowledge of the underlying- pathophysiology of nocturnal enuresis. Over the last 13 years, enuresis studies at the Institute o f Experimental Clinical Research, the University of Aarhus, Denmark, h ave focused on sleep disturbances, bladder reservoir function, urine o utput, and a combination of the three. Sleep studies indicate that: en uretic patients are normal sleepers; the voiding characteristics of an enuretic episode are similar to those of voluntary voiding during the day; and enuresis can take place during any stage of sleep, but gener ally occurs when the bladder is filled to the equivalent of maximal da ytime functional capacity. Bladder reservoir capacity appears to be no rmal and bladder instability an unimportant factor in the pathology of nocturnal enuresis. However, enuretic patients have been shown to lac k the normal nocturnal increase in antidiuretic hormone levels and had nocturnal urine production up to four times the volume of functional bladder capacity, which explains the need for bladder emptying. These findings open new avenues to the approach to treatment based on antidi uretic therapy.