Nighttime bedwetting is most often caused by nocturnal enuresis. The diagnosis is made by excluding any other cause for bedwetting. Most children who present with primary enuresis have never had a prolonged period of dryness. In some, enuresis may be secondary to stress or illness. When daytime incontinence also occurs, bladder dysfunction is most commonly responsible, followed by urinary tract abnormalities or nerve disorders. Evans reviewed the treatment choices for nocturnal enuresis (see accompanying table).

Treatments have been compared in two recent systematic reviews. Alarms that waken children during the night when they are wetting can have good success, but the relapse rate is high. Dry-bed training, a routine of enuresis alarms, waking routines, and training with rewards (star charts), is as effective as the use of an alarm alone. To be effective, enuresis alarms must be used for several months.

Drug therapy can be effective, but it can also have serious side effects. Desmopressin successfully decreases wet nights and promotes consistent dryness, but relapse is frequent after the drug is stopped. Imipramine also can be successful during administration. A small comparison study demonstrated that these two drugs are equally efficacious. Treatment decisions can then be made on the basis of side effect profile. Tricyclic antidepressants appear to have more frequent side effects than desmopressin. Tricyclics can cause drowsiness, lethargy, depression, agitation, sleep disturbance, and gastrointestinal upset, while desmopressin can result in nasal irritation or nosebleed, as well as the rare but serious effect of water intoxication, resulting in severe neurologic disturbance. The effectiveness of monotherapy with oxybutynin is uncertain, but the drug may benefit children with bladder instability when taken in combination with desmopressin. Together, desmopressin and an enuresis alarm can provide better results than the alarm alone.

Evans concludes that children with primary nocturnal enuresis who are in a supportive environment and do not have bladder instability or dysfunction will do best with either desmopressin or the alarm.

editor's note: Desmopressin is useful in the management of nocturnal enuresis but requires close supervision. In a case reported in 1999, a 6-year-old child developed water intoxication–induced convulsions and coma following unsupervised excessive intranasal usage. Parents and children are highly embarrassed by nighttime bedwetting, and there is a tendency to think that if a prescribed amount of medication is good, a bit more might be better. The initial presentation of these overdosed children may include seizures or mental status changes. Most recover easily and quickly if they stop taking the medication. Intranasal desmopressin should be administered under the observation of parents who are well-informed about the potential side effects and risks of increased fluid intake.—r.s.