Overactive Bladder in Children Treatment & Management

Although neuromodulation is used more commonly in adults, this treatment approach has been used in children in whom behavioral and pharmacologic therapy fails. The exact mechanism by which neuromodulation affects detrusor overactivity is not fully understood. Sacral nerve stimulation may induce reflex-mediated inhibitory effects on the detrusor through afferent and/or efferent stimulation of the sacral nerves. In addition, stimulation of the somatic fibers of the nerves may activate the pelvic floor muscles, causing further detrusor inhibition.^[27]

The procedure requires surgery; thus, many parents are reluctant to proceed. In addition, the current version of the device is relatively large for a child, so this procedure may be more attractive to parents when a smaller device becomes available.

Transcutaneous stimulation has been used in children. This involves placement of surface electrodes to stimulate the sacral root (S3). Several stimulation frequencies have been used, and stimulation of 2 Hz seems to be sufficient. Researchers have not yet determined the optimal length of each stimulation during a treatment session nor how many sessions the treatment should continue.^[28]

Surgical procedures such as bladder augmentation or autoaugmentation are rarely needed in children with idiopathic OAB but may be indicated in children with neurogenic OAB refractory to medical therapy.

Dietary changes are helpful in some children, particularly those who drink caffeinated or acidic fluids and those with increased fluid intake.

Behavioral therapy is an important component in the management of OAB, and clinicians should ensure that such regimens are being followed for maximal response.

Although the urodynamic effects of anticholinergic agents occur within 24 hours of dosing, the clinical effects tend to take longer. The authors recommend that an individual remain on an anticholinergic agent for at least 2-4 weeks before determining whether the medication is effective. Furthermore, in individuals who note some response to therapy, improvement may increase throughout the first month of therapy. Thus, the effectiveness of the medication should be evaluated.

In children who respond to anticholinergic therapy, the child should remain on therapy for 3-6 months before attempting to wean off the therapy. If the weaning fails, the child should return to the dose that kept his or her symptoms controlled for an additional 3-6 months before attempting another trial of weaning.

In children who are refractory to behavioral therapy and anticholinergic therapy, further evaluation is indicated. Urodynamic studies are helpful to evaluate bladder and sphincteric function in these children. In addition, children who do not respond to therapy should be reassessed to rule out an underlying neurologic etiology.

Initial management of overactive bladder (OAB) involves a behavioral and cognitive approach. The child and caregiver must be educated on normal bladder and sphincter function. Pharmacologic treatment is initiated if behavioral therapy fails or symptoms are severe. Medical comorbidities should be treated. Surgical treatment may be considered if behavioral therapy and pharmacologic therapy fail.

As with adults, older children often institute various coping strategies, including defensive voiding, toilet mapping, and restriction of fluid intake. Thus, the management of OAB must consider not only the detrusor overactivity but also the responses to it.^[18] The volume and types of fluids should be assessed and modifications made to encourage normal fluid intake as well as avoidance of potential bladder irritants and diuretics such as caffeine.

Constipation, if present, must be treated.

Urinary tract infections (UTIs) should be treated and, depending on the child’s age and whether the UTIs have been febrile or nonfebrile, investigated further with renal ultrasonography and voiding cystourethrography (VCUG). In children with recurrent UTIs, antibiotic prophylaxis may be helpful in decreasing the number of infections while voiding and bowel habits are being managed. Nitrofurantoin or trimethoprim-sulfamethoxazole, at one third to one half of the normal treatment dose administered once per day, is the typical choice for prophylaxis.

Voiding regimens are instituted in all children with OAB. Voiding is recommended every 2-3 hours while the child is awake. This often requires assistance from teachers to ensure that the child is complying with a voiding regimen at school.

In children who do not empty their bladder completely (increased postvoid residual volume), the practitioner should institute a double voiding regimen, whereby the child voids and then waits a minute or two and tries to void again to improve bladder emptying.

Biofeedback-assisted therapy

In children who fail to improve with such voiding regimens, biofeedback-assisted therapy and pharmacologic therapy are the next treatment options.

Biofeedback is a technique in which physiologic activity is monitored, amplified, and conveyed to the patient as a visual or acoustic signal, providing the patient information about unconscious physiologic processes. It has been used for both filling-phase (detrusor overactivity) and voiding-phase (voiding dysfunction) abnormalities.

Biofeedback can help children identify and suppress involuntary detrusor contractions, as well as identify and relax their pelvic floor muscles. The limitation of biofeedback in the management of detrusor overactivity is the need for the placement of a catheter and the potential need for multiple sessions.

In children with associated pelvic floor dysfunction, biofeedback may be performed via the use of a uroflow with electromyography (EMG). The EMG activity can be identified on the monitor and followed as the child first locates and then learns to relax his or her pelvic floor muscles.

Few studies have evaluated urodynamic-based biofeedback in children with detrusor overactivity. The small numbers of patients and the variability in study design limit the value in drawing conclusions.

Kjolseth et al performed cystometrography-assisted biofeedback in 15 children aged 6-12 years with idiopathic detrusor overactivity. The children received 1-2 inpatient sessions, and follow-up sessions were determined by the severity of the child’s symptoms and the ease of learning for the child. A pronounced improvement was noted in 60% of children, and some improvement was noted in 13% of them. The children were monitored for up to 2 years after the end of therapy, and, in all children but one, the beneficial effects were maintained.^[19]

If behavioral therapy fails or the child has severe symptoms, pharmacologic therapy is instituted. Although pharmacologic therapy is one of the mainstays in the treatment of adult OAB and the management of neurogenic detrusor overactivity, its role in the treatment of idiopathic OAB in children is less well defined.

Anticholinergics

The use of anticholinergic therapy in the management of OAB is predicated on the concept that parasympathetic mediated stimulation of muscarinic receptors (M3 primarily) in the bladder leads to detrusor overactivity. Anticholinergic/antimuscarinic agents have been demonstrated to increase bladder capacity, to improve bladder compliance, and to decrease uninhibited detrusor contractions.

Anticholinergic agents are often used in children with OAB when behavioral therapy has failed or as an adjunct to behavioral therapy. Despite the frequent use of anticholinergic agents in children with OAB, few randomized studies have assessed the drug safety and efficacy.

In a review of all randomized controlled trials for the treatment of daytime incontinence in children from 1996-2001, only 5 trials were found to compare 2 or more interventions using a randomized controlled design.^[20] Of these 5 studies, 4 evaluated the use of pharmacologic agents. Of the 4 pharmacologic studies, 2 evaluated the use of terodiline (which is no longer available), 1 evaluated imipramine, and 1 evaluated oxybutynin.

Currently, the most commonly used anticholinergic for the treatment of OAB in children is extended-release oxybutynin (Ditropan XL). This agent is a once-a-day formulation that is available and approved for use in children who can swallow a pill and who meet the drug’s age requirements.^[21]

Historically, oxybutynin use has been limited by side effects, most notably dry mouth and constipation. In addition, the need for dosing 2 or 3 times daily may affect compliance. The extended-release preparation decreases such side effects. The risk of side effects appears to be dose-related. Both oral oxybutynin and intravesical oxybutynin may have side effects involving the central nervous system (CNS) and cognitive function.^{[22, 23]} However, such reports have not been documented with extended-release oxybutynin.

Extended-release oxybutynin is delivered via the osmotic release oral system (OROS). The tablet cannot be crushed, cracked, or chewed and must be swallowed whole. Oxybutynin is metabolized by the cytochrome P-450 (CYP-450) enzyme systems, particularly the CYP3A in the liver and gut wall. The pharmacokinetics of extended-release oxybutynin were evaluated in 19 children aged 5-15 years with neuropathic detrusor overactivity and were found to be consistent with those reported for adults.

The contraindications to the use of extended-release oxybutynin in children are the same as those in the adult population (ie, urinary retention, severe decreased gastrointestinal motility conditions, uncontrolled narrow angle glaucoma). Caution should be used in treating patients with severe hepatic impairment and those on potent CYP3A4 inhibitors.

A 24-week open-label trial that studied the safety and efficacy of extended-release oxybutynin in 60 children aged 6-15 years with neuropathic detrusor overactivity demonstrated that this agent, in doses ranging from 5 to 20 mg yielded an increase from baseline in mean urine volume per catheterization and an increase from baseline in the mean percentage of catheterizations without a leaking episode (Ditropan XL Prescribing Information, Alza Corporation/Ortho-McNeil). Urodynamic results were found to be consistent with clinical results.

The recommended initial starting dose of extended-release oxybutynin in children aged 6 years or older is 5 mg/d. The dosage may be increased in 5-mg increments up to a maximum of 20 mg/d to achieve a balance of efficacy and tolerability.

Side effects of extended-release oxybutynin are those commonly encountered with anticholinergic agents, including dry mouth, constipation, facial flushing, central nervous system effects (headache, dizziness, somnolence), and blurred vision. The incidence of side effects with extended-release oxybutynin is significantly lower than with other oxybutynin formulations, particularly with respect to dry mouth and constipation.

Other agents used in the treatment of adult OAB have also been used in children. Tolterodine (Detrol), a nonselective antimuscarinic agent with a favorable tolerability profile compared with that of oxybutynin, has been studied in children. However, no pediatric indication is listed in the labeling. Tolterodine is metabolized in the liver, and the active metabolite has a therapeutic effect that is similar to that of oxybutynin. The pharmacokinetics of tolterodine in children have not been established (Detrol Prescribing Information, Pfizer).

Because tolterodine is metabolized by the liver, care should be taken with agents that affect CYP2d6 and CYP3A4 activity, and practitioners should adjust dosage in patients with severe liver disease. Tolterodine is contraindicated in patients with urinary retention, gastric retention, uncontrolled narrow-angle glaucoma, or documented hypersensitivity to the drug or its ingredients.

Safety and efficacy studies performed in European children on oral tolterodine doses ranging from 0.5 to 2.0 mg twice daily for 14 days demonstrated a 21% mean decrease from baseline in micturition frequency and a 44% mean decrease from baseline in the number of incontinence episodes among children who received the 1-mg dose.^[24]

The efficacy of tolterodine in children has not been determined. The results of 2 pediatric phase III, placebo-controlled, double-blind, 12-week studies demonstrated aggressive, abnormal, and hyperactive behavior and attention disorder in 2.9% of children treated with Detrol LA compared with 0.9% treated with placebo. The most common adverse events were dry mouth, constipation, headache, vertigo/dizziness, and abdominal pain. Patients also reported abnormal vision (accommodation abnormalities), an expected side effect of an antimuscarinic agent.

Trospium chloride (Sanctura), another agent used in adults, has been studied in a small series of children, with dosages ranging from 10 to 25 mg/d, divided into 2 doses daily; overall, 32% of the subjects had an excellent response to the drug, 42% a good response, and 8% a fair response.^[25] Detrusor overactivity resolved completely in 35%. Trospium is currently approved for use in the United States for adults in a dose of 20 mg orally twice daily. No dosing guidelines or safety and efficacy information are available regarding its use in children.

Other newer anticholinergic agents used in adult patients with OAB that have not been studied in children include solifenacin (Vesicare) and darifenacin (Enablex).

Botulinum toxin

Botulinum toxin is currently being used to treat pediatric detrusor overactivity, particularly cases with a neurogenic cause. In children, a total of 50-100 IU, on average, is injected in 30-40 bladder sites. The results last 6-9 months.^[26] Although the initial results in children seem promising, researchers need to perform additional studies on this treatment approach.

Botulinum toxin interacts with the protein complex necessary for the release of acetylcholine and other transmitters from the presynaptic nerve endings and prevents the release of the transmitters from the presynaptic vesicles. This effect results in decreased muscle contractility and atrophy at the injection site.

The use of botulinum toxin in children is limited by the need for preinjection anesthesia and the need for repeat injections. Few data are available regarding the dose, concentration, site or sites, number of injections, long-term efficacy, and side effects in both adult and pediatric patients with OAB. In adults, generalized weakness and development of resistance to the toxin has been reported.