Overactive Bladder

Urinary frequency, urgency and urge incontinence are manifestations of bladder instability. This instability is usually not due to some neurological disorder and often responds quite well to an antispasmodic such as Ditropan, Pro-Banthine or one of the other antispasmodics.

A significant number of children have daytime wetting in addition to their bed wetting problems, requiring evaluation by the pediatric urologist to rule out associated conditions. Children with complicated bed wetting are unlikely to respond to the DDAVP and/or Tofranil unless their bladder instability is treated with an antispasmodic.

All children who have had daytime voiding problems, soiling problems, headaches, thirst problems or an abnormal urinalysis/urine culture demand evaluation.

The most common daytime urinary problems complicating the treatment of bed wetting are urinary frequency, urgency and/or urge incontinence (bladder instability). Evaluation by the pediatric urologist is important to identify the small number of children with bladder instability who may have important causes for complicated wetting.

Children with bladder instability (especially girls) are at risk for urinary tract infections.

All children with a bona fide urinary tract infection demand evaluation, usually through a renal sonogram and VCUG as well as other studies as indicated.

Further evaluation of those with urinary tract infections is important to rule out the 50% of children with an infection who have an underlying cause for their problem such as reflux, hydronephrosis or, in boys, missed posterior urethral valves or strictures. However, these problems can be present without infections.

It is extremely important to remain cognizant of a few unusual causes of complicated bed wetting demanding review:

1. The sacrum should be examined to note sacral dimples and/or other cutaneous manifestations which may suggest sacral dysraphism and a possible tethered cord as a neurogenic cause of bladder instability.
2. Bowel disturbances with soiling are not unusual in children with associated bladder instability. Most children with soiling do not have an associated neurologic cause for their soiling, but this may still need to be considered. Soiling can be treated with periodic oral mineral oil. They may also need evaluation by the pediatric gastroenterologist.
3. In girls, the presence of some wetting day and night and constant dampness without urgency may suggest an ectopic ureter, which can be detected on a carefully performed intravenous pyelogram (IVP) to review kidney anatomy.
4. Increased thirst, fluid intake or amounts of urine may suggest one of the forms of diabetes, such as diabetes mellitus, diabetes insipidus or nephrogenic diabetes. These disorders can be picked up on a careful history, a urinalysis and also by checking the specific gravity.
5. Headaches, etc. rarely may suggest a craniopharyngioma or other CNS cause for bladder instability.

The indications for formal urodynamic assessment are uncommon and usually do not alter the treatment options but may be reasonable in those children who fail to respond to conventional treatment.

PATTERNS OF FUNCTIONAL VOIDING DISORDERS

1. The Daytime Frequency/Urgency Syndrome (No Incontinence)

This is urinary frequency associated with the passage of small volumes frequently, and in the absence of any other significant urinary problem is usually a benign condition. These children usually do not have any voiding disorders and do not have true bladder instability. They usually do not respond to antispasmodic medication, and this problem is usually self-limiting after weeks to months. It is not behavioral.

2. Bladder Instability

Bladder instability because of an overactive bladder muscle manifested through daytime frequency/urgency, urge incontinence and possibly nocturnal enuresis.

Radiological evaluation is usually normal, but urodynamic studies typically demonstrate uninhibited bladder contractions during bladder filling.

Often, the parents can describe the characteristic postures of fidgeting and crossing legs and/or squatting (Vincent’s curtsy) in the child’s effort to prevent urinary leakage during an unstable bladder contraction. Parents often suggest that the child leaks because he or she has waited until the last minute. However, these contractions can occur at any bladder volume and come on quite suddenly and are not behavioral. Rarely there may be an important neurological cause such as spina bifida occulta. Bladder antispasmodics such as Ditropan or Pro-Banthine usually work well in those children who have no cause to their bladder instability.

3. Infrequent Voiding (lazy bladder syndrome).

Children who void infrequently are usually older girls, first seen because of recurrent symptomatic or asymptomatic urinary tract infections with or without some daytime wetting and/or bed wetting. These children often void several hours after getting up and may not void at all while at school. Such increasing bladder capacity can lead to bladder muscle failure, resulting in incomplete bladder emptying and straining to void. Many of these children are also chronically constipated, which also requires treatment.

A significant bladder residual can be documented on a post-void bladder ultrasound, and these children can be treated through a timed and double voiding regimen.

4. Small Capacity Hypertonic Bladders

Children with this anatomy typically have recurrent urinary tract infections in addition to the symptoms of bladder instability. During voiding, the external sphincter may relax incompletely or intermittently and this can be documented on a VCUG, revealing some dilatation of the proximal urethra. Vesicoureteral reflux may also be present. These children often respond to a combination of bladder antispasmodics and prophylactic antibiotics.

5. Non-neurogenic Voiding Dyssynergia

This is an unusual problem in some children, where the bladder contracts against a closed sphincter of neurologically intact children. This set of circumstances can lead to impressive uroradiological findings and, if untreated, can lead to renal failure.

These children typically have longstanding recurrent urinary tract infections and an intermittent urinary stream associated with straining to void. Most also have associated constipation and soiling.

Most of these children will need a combination of treatments involving timed voiding, prophylactic antibiotics, relaxation of the sphincter and bladder neck through Diazepam and alpha adrenergic blockage, biofeedback and/or clean intermittent catheterization in addition to a bowel program and laxatives.

SUMMARY

Isolated wetting during sleep in the absence of any other significant urinary symptoms or findings usually does not need further evaluation and routinely responds well to a bedtime medication such as DDAVP or Tofranil.
However, wetting during sleep in association with daytime voiding problems demands further evaluation and treatment and does not usually respond to a bedtime medication on its own.