To Örebro University

Objective: To investigate whether rapid maxillary expansion (RME) is a useful treatment method for nocturnal enuresis (NE) and whether the treatment effect is due to placebo. The study also aimed to identify prognostic variables in patients responding to treatment.

Materials and Methods: Thirty-eight children with therapy-resistant NE were recruited and randomized into two groups: the intervention group or placebo group. Both groups were treated with RME, but the placebo group received treatment with a sham appliance for 2 weeks before having the actual treatment. A medical history focused on micturition habits, previous treatment, heredity, and sleep disorders was taken. Daytime voided volumes and nocturnal urine production during wet nights were recorded before the intervention.

Results: Of the 38 patients recruited, two dropped out as one patient was unable to take dental impressions and one refused to have the appliance fitted. There was a statistically significant reduction of wet nights after the RME treatment (P<.001). No significant reduction was found after the placebo treatment (P<.40). Eleven patients (35%) had their enuresis frequency reduced by >50%. Large voiding volume and a wide maxilla at baseline had a strong association with positive treatment outcome.

Conclusions: RME has a modest effect on children with therapy-resistant NE. The treatment outcome does not seem to be due to a placebo effect of the appliance. A wide maxillary width and large voiding volume at baseline seem to be positive predictors regarding response to treatment.