T Gera, A Seth, J Mathew
enuresis, medicine, neonatology, nocturnal enuresis, pediatrics
T Gera, A Seth, J Mathew. Nocturnal Enuresis In Children. The Internet Journal of Pediatrics and Neonatology. 2000 Volume 2 Number 1.
A myriad of disorders lead to a wet child and nocturnal enuresis is not at all unusual in pediatric population. It is a problem that is often ignored by the treating paediatrician, but is a source of psychological stress for the affected child as well as the parents. Increasing attention is now being focussed on the problem but a number of questions regarding the etiology and the management still elude an answer. This article aims at presenting a review of the current information on nocturnal enuresis, including the mechanisms for urinary continence, the etiopathogenesis and the available therapeutic modes, keeping the main focus on primary nocturnal enuresis.
Nocturnal enuresis refers to involuntary passage of urine during sleep by a child old enough to have gained urinary control. The American Psychiatry Association has defined bed wetting as children older than age five who are incontinent of urine at night (1). Some investigators make a distinction between primary and secondary incontinence. Primary incontinence is lifelong bed wetting whereas secondary enuresis occurs when continence is lost after having been dry for more than six months. Secondary enuresis often implies loss of normal continence mechanisms and suggests that underlying disease may be present.
Another classification of nocturnal enuresis is based on the presence or absence of other bladder symptoms. Polysymptomatic nocturnal enuresis is bed-wetting associated with severe urgency, severe frequency, or other signs of an unstable bladder. Monosymptomatic nocturnal enuresis is associated with normal daytime urination and is easier to treat, as compared to the former.
DEVELOPMENT OF URINARY CONTINENCE
Urinary continence is a normal process of maturation. During the infantile period voiding is a spinal reflex with co-ordination of the sphincter (2).The bladder fills at low pressure, but not necessarily to capacity and empties in a co-ordinated manner at the time of voiding with simultaneous contraction of the detrusor and relaxation of the pelvic floor (3). The reflex is coordinated at the level of pontine mesencephalic reticular formation with no voluntary control or modulation of the process.
Between 2-4 years the children exhibit a transit in period of voiding. During this period toilet training is also initiated leading to creation of a “social awareness” of acceptable time and place for toileting. However the conscious modulation of voiding remains deficient as uninhibited bladder contractions still occur and may produce voiding at less than capacity and at socially inappropriate times. At times the child postpones micturition by contracting the pelvic floor to produce bladder outlet obstruction until the urge to void is suppressed. This attempt to achieve social continence is a voluntary mechanism of vesicosphincter discoordination and is soon abandoned. Abnormal persistence of this voiding pattern beyond this age may lead to dysfunctional voiding (4).
With neurological and behavioural maturation the older child is able to void at less than capacity or postpone voiding until absolute capacity is reached. There are no uninhibited contractions and the voiding is well coordinated withy simultaneous pelvic floor relaxation and detrusor contraction.
The prevalence of nocturnal enuresis has been difficult to estimate because of variations in definiton and in social standards (5,6). It is estimated that 15-20% of children have some degree of bedwetting at five years of age, with a spontaneous resolution rate of 15% per year. Bedwetting has been reported to be higher in males – 60% of bedwetters and more than 90% of nightly bedwetters are males. However this finding has been disputed by other reports (7).
An organic cause to nocturnal enuresis may be elicitible in only 2-3% of the patients. Another 5-10% children have polysymptomatic enuresis which requires specific therapy. The causes of organic enuresis are listed in Table 1.
Physiologic or Primary Nocturnal Enuresis
It is vital to remember that primary nocturnal enuresis is a diagnosis of exclusion and other causes of bed-wetting must be ruled out. The etiology of primary nocturnal enuresis has been widely debated but is still not completely understood. The final common pathway for all affected children is an inability to recognise the sensation of a full bladder during sleep and to awaken from sleep to go to the toilet. Another etiologic requirement is that the bladder reaches capacity during the night. The possible mechanisms are discussed in detail below:
Nocturnal enuresis is also associated with episodes of obstructive sleep apnea in children with upper airway obstruction and surgical correction in such cases (viz. tonsillectomy, adenoidectomy etc.) diminishes the episodes of bedwetting (14).
The impact of psychologic problems primarily manifests as poor compliance with the treatment regime. Also enuresis itself may lead to lowered self-esteem and psychologic problems in the ‘wet’ child.
OFFICE EVALUATION OF A WET CHILD
The evaluation is aimed at detection of organic enuresis. It is also important to consider the patient’s age, the severity of the problem, the perception of seriousness of illness by the family and the acceptability of treatment.
History: A history of dysuria, intermittent daytime wetness, polydipsia, polyuria, CNS trauma, constipation and encopresis point to medically treatable conditions. Surgical management may be considered in patients with constant wetness (ectopic ureter), abnormal urine stream with hesitancy or dribbling (posterior urethral valve), alteration in gait (spinal cord neoplasm) or snoring (adenoid hypertrophy). Psychosocial and family histories are important to assess the attitude of parents and the child, in order to select a proper therapy.
Physical Examination: The physical assessment should include a thorough examination of the genitals (for meatitis, vulvitis, labial adhesions or signs of sexual abuse), bladder and bowel (distended bladder, fecal impaction) and the neurological system. A careful observation of the child’s gait, muscle tone, strength and deep tendon reflexes in the lower extremity may reveal a CNS etiology. Examination of the lumbosacral area may disclose an overlying midline defect. It is also important to check the patient for obligatory mouth breathing as children with adenoid hypertrophy may wet themselves during sleep apnea and the problem is alleviated by adenoidectomy.
Investigations: The following investigations would be useful in detecting the cause of enuresis, if any, and to rule out primary nocturnal enuresis.
a) Specific gravity (s.g.>1.015 rules out diabetes insipidus)
b) Glucose (for diabetes mellitus)
c) Urine culture, if symptoms of urinary tract infection are present, or the patient has had a UTI in the past.
2. Radiologic studies are not necessary in all children with straightforward primary nocturnal enuresis.
a) Micturating cystourethrogram (MCU) is required in children with symptoms of urinary tract obstruction or a neurogenic bladder.
b) Bladder ultrasonography (pre- and post-voiding) is indicated in children with diurnal enuresis, unresponsive to therapy, to rule out partial emptying.
Radiologic studies are also done in infant and young children with UTI to rule out structural abnormalities.
Determination of Bladder Capacity: This is an extremely important part of the evaluation of a child with bedwetting, that is often overlooked. It can be easily done by asking the child to drink 12 oz. of water in the OPD and measure the volume of urine when the child voids. The normal bladder capacity, in ounce, is age(in years)+2 (the normal adult bladder capacity is 12-16oz.). This helps in better understanding of the child’s problems among the two primary etiologies-small bladder and inability to awaken. If the bladder capacity is normal the condition is more amenable to motivational therapy. If the bladder capacity is normal or low, treatment is more difficult.
Before starting management the physician should keep in mind that children younger than six years with enuresis and other urologic problems do not require an evaluation. However parents need to be reassured that bedwetting is due to maturational delay and any punishment is unwarranted. Treatment modalities require consistent support and cooperation from the child and the family and are unlikely to succeed in their absence.
It is also important to preserve the child’s self esteem till appropriate therapy is established.
Consistent follow up is essential to assess the results of the intervention. Improvement is defined as a 50% reduction in the number of nights that bedwetting occurs. Resolution is defined as only one or two wet nights over a three-month period, and documentation that the child wakes up spontaneously to void.
Treatment for Organic Enuresis
Diurnal enuresis deserves a detailed evaluation. Children with recurrent UTIs are given prophylactic antibiotics. Children with chemical urethritis must be advised to avoid soaps and other irritants. In atopic patients with diuresis, the aggravating food allergies should be eliminated from the diet. Children who have associated constipation need this symptom treated first.
Treatment of primary nocturnal enuresis can be divided into two major categories: pharmacological and non-pharmacological.
This includes motivational therapy, behaviour modification, bladder training exercises, diet therapy and hydrotherapy.
Hypnotherapy, diet therapy and physiotherapy have not been extensively used. Hypnotherapy and psychotherapy has been successful in limited trials. Diet therapy has been successful in some patients. Enuresis inducing food agents include caffeine containing products, dairy products, chocolates, citrus fruits and juices (24).
Several drugs have been used for the treatment of nocturnal enuresis. None of these agents offer a definitive cure but may provide a stopgap measure until the child is able to wake up in the night to void. Drug therapy is often reserved for children who have not responded to other treatment options.
The starting dose for all ages is 20 mcg (one spray into each nostril). The response to therapy is evaluated after 2 weeks and the dose can be increased by 10mcg weekly to a maximum of 40 mcg. In patients more than 12 years of age upto 60 mcg of DDAVP can be administered safely. For any patient who remains dry on given dose, a dose of 10 mcg less should be tried. The subsequent therapy should be continued for at least 3-4 months. Abrupt stoppage of therapy is associated with a high incidence of relapse; therefore it is preferable to taper the dose slowly in decrements of 10mcg per month.
The side effects of desmopressin are negligible and include headache, abdominal pain, nausea and nasal discomfort. Two cases of symptomatic hyponatremia on DDAVP therapy have been reported (28, 31); hence it is recommended that serum electrolyte levels of patients on this drug should be monitored periodically. The drug is contraindicated in patients with habit polydipsia, hypertension or heart disease. Long term therapy with DDAVP has been shown to be safe. The efficacy of desmopressin in several double blinded RCTs has varied from 10-70% (32, 33, 34). Desmopressin may be used on as-needed basis in patients who have responded to it and need temporary relief to overcome difficult psychological situations. The major limting factor for the use of desmopressin is its prohibitive cost.
CHOICE OF TREATMENT MODALITY
After evaluating the cost, efficacy, side effects and the relapse rates associated with various treatments, the enuresis alarms seem to be most efficacious because the cure is permanent, cost is low with no significant side effects. Drugs are useful for short term use and it is considered appropriate to use drugs intermittently in children older than 8 years of age.
Children who have frequent episodes of enuresis should use a combination of a drug and an enuresis alarm. The drug reduces the necessity of awakening at night and alarm provides the backup. After the child is dry for more than 3 weeks the drug can be tapered gradually.
Combination drug therapy may be tried in patients with refractory primary nocturnal enuresis when neither alarm nor pharmacologic therapy is effective. In such cases combination therapy using 2 or more drugs has been shown to be effective.
There is no consensus about which children should be put on continous medication. Some authors advise that it should be prescribed in older patients who have refractory enuresis and whose parents are unwilling to awaken the children at night. The duration of therapy in such cases presents a dilemma because most of such patients tend to relapse when medication is stopped. Such patients are advised to reinitiate alarm therapy every 6 months and attempt to taper the medication. If even after repeated attempts the child does not learn to self awaken then the physician has the option of continued symptomatic cure with drugs, after discussing the potential adverse effects with the parents.