Enuresis

Description

• Classification
  • Primary nocturnal enuresis (NE): 80% of all cases; person who has never established urinary continence on consecutive nights for a period of ≥6 months
  • Secondary NE: 20% of cases; resumption of enuresis after at least 6 months of urinary continence
• NE: intermittent nocturnal incontinence after the anticipated age of bladder control (age 5 years)
  • Primary monosymptomatic NE (PMNE): bed-wetting with no history of bladder dysfunction or other lower urinary tract (LUT) symptoms
  • Nonmonosymptomatic NE (NMNE): bed-wetting with LUT symptoms such as frequency, urgency, daytime wetting, hesitancy, straining, weak or intermittent stream, post-urination dribbling, lower abdominal or genital discomfort, or sensation of incomplete emptying
    ALERT
    Adult-onset NE with absent daytime incontinence is a serious symptom; complete urologic evaluation and therapy are warranted.
• System(s) affected: nervous, renal/urologic
• Synonym(s): bed-wetting; sleep enuresis; nocturnal incontinence; primary NE

Epidemiology

Incidence

• Depends on family history
• Spontaneous resolution: 15% per year

Prevalence

• Very common; 5 to 7 million children in the United States
• 10% of 7-year-olds; 3% of 11- to 12-year-olds; 0.5–1.7% at 16 to 17 years old (1)
• 2 to 3 times more common in males than females
• Nocturnal > daytime (3:1)

Geriatric Considerations
Infrequent; often associated with daytime incontinence (formerly referred to as diurnal enuresis)

Etiology and Pathophysiology

• A disorder of sleep arousal, a low nocturnal bladder capacity, and nocturnal polyuria are the three factors that interrelate to cause NE.
• Both functional and organic causes (below); many theories, none absolutely confirmed
• Detrusor instability
• Deficiency of arginine vasopressin (AVP); decreased nocturnal AVP or decreased AVP stimulation secondary to an empty bladder (Bladder distension stimulates AVP.)
• Maturational delay of CNS
• Severe NE with some evidence of interaction between bladder overactivity and brain arousability: association with children with severe NE and frequent cortical arousals in sleep
• Organic urologic causes in 1–4% of enuresis in children: urinary tract infection (UTI), occult spina bifida, ectopic ureter, lazy bladder syndrome, irritable bladder with wide bladder neck, posterior urethral valves, neurologic bladder dysfunction
• Organic nonurologic causes: epilepsy, diabetes mellitus, food allergies, obstructive sleep apnea, chronic renal failure, hyperthyroidism, pinworm infection, sickle cell disease
• NE occurs in all stages of sleep.

Genetics
Most commonly, NE is an autosomal-dominant inheritance pattern with high penetrance (90%).

• 1/3 of all cases are sporadic.
• 75% of children with enuresis have a first-degree relative with the condition.
• Higher rates in monozygotic versus dizygotic twins (68% vs. 36%)
• If both parents had NE, risk in child is 77%; 44% if one parent is affected. Parental age of resolution often predicts when child’s enuresis should resolve.

Risk Factors

• Family history
• Stressors (emotional, environmental) common in secondary enuresis (e.g., divorce, death)
• Constipation and/or encopresis
• Organic disease: 1% of monosymptomatic NE (e.g., urologic and nonurologic causes)
• Psychological disorders
  • Comorbid disorders are highest with secondary NE: depression, anxiety, social phobias, conduct disorder, hyperkinetic syndrome, internalizing disorders.
  • Association with ADHD; more pronounced in ages 9 to 12 years
• Altered mental status or impaired mobility

Commonly Associated Conditions

• Obstructive sleep apnea syndrome (10–54%) (2): Atrial natriuretic factor inhibits renin-angiotensin-aldosterone pathway leading to diuresis.
• Constipation (33–75%) (2)
• Behavioral problems (specifically ADHD in 12–17%) (2)
• Overactive bladder or dysfunctional voiding (up to 41%) (2)
• UTI (18–60%) (2)