Prepulse inhibition of the startle reflex for differentiation of enuresis in children

Children with enuresis can be classified into those who wet their beds only at night (monosymptomatic enuresis, mE), and those who additionally suffer from daytime symptoms, such as urgency or incontinence (non-monosymptomatic enuresis, nmE). Evidence is growing that enuresis may have a central origin: bedwetting children have lower brainstem reflex control (impaired prepulse inhibition) than normal controls. However, findings on this subject are inconsistent. To date, there has been no study in pediatric patients according to the type of enuresis. With the aim of determining whether mE and nmE children differ in terms of central reflex control, we divided 30 enuretic children into two groups (mE and nmE) based on data recorded in a bladder diary and clinical history (19 with history of diurnal urge, 11 without; age 5-14 years). Prepulse inhibition (PPI) of the startle reflex of the children was measured and compared between groups. A significant difference in PPI was observed between the groups, with the nmE group having a lower median PPI level than the mE group (10 vs. 73%, respectively; p = 0.0002). These findings lead to the assumption that a loss of central control plays a role only in the etiology of nmE. Moreover, they may throw a new light on the classification of enuresis.