Overactive Bladder, a commonly missed cause of Nocturnal Enuresis

Technical Summary: Overactive Bladder as a Commonly Missed Cause of Nocturnal Enuresis

Problem Statement
Nocturnal enuresis (NE) is a multifactorial condition often categorized as either monosymptomatic (MNE), characterized by nighttime wetting with normal daytime voiding habits, or non-monosymptomatic (NMNE), where daytime voiding symptoms (DVS) coexist. The primary clinical challenge addressed in this study is the frequent underrecognition of DVS associated with overactive bladder (OAB) in children presenting with NE. OAB, defined by involuntary detrusor contractions and urinary urgency, can reduce functional bladder capacity and predispose children to NE. However, because children with OAB often employ compensatory pelvic tightening maneuvers (PTM) to prevent leakage while awake, they may not report daytime incontinence. Consequently, patients with underlying OAB are frequently misdiagnosed as having MNE. This misclassification is critical because standard first-line therapies for MNE (e.g., desmopressin, enuresis alarms) do not address the underlying OAB, potentially leading to treatment failure.

Methodology
The authors conducted a retrospective analysis of a database comprising 1,581 children aged 5–15 years referred to a single pediatric nephrology center between 2007 and 2025 for voiding problems.

• Inclusion/Exclusion: The study included children with voiding problems but excluded those with neurogenic lower urinary tract dysfunction, structural anomalies, impaired urinary concentration (specific gravity < 1.015), or substantial developmental delays.
• Data Collection: A standardized clinical evaluation template was used to document voiding and bowel habits, medical/family history, and physical examinations. Crucially, DVS were not solely reliant on initial patient/parent reports; they were elicited through detailed, directed questioning and simulation of PTM.
• Definitions:
  • DVS (OAB): Presence of >2 symptoms (urgency, urge incontinence, PTM, hesitancy) occurring >5 times/week for ≥3 months.
  • NE: ≥1 episode of wetting/week over 3 months.
  • Sleep Arousal: Assessed via an 8-point scale (validated by Chandra et al.) where higher scores indicate difficulty awakening.
• Statistical Analysis: Comparisons were made between MNE, NMNE, and a cohort of children with isolated DVS (DVS without NE). Logistic regression was used to identify clinical predictors of NMNE.

Key Contributions and Results
The study analyzed 1,003 children with NE and 578 with isolated DVS. The distribution of NE cases revealed that 83.8% (841/1,003) were NMNE, while only 16.2% (162/1,003) were MNE. Notably, 80% of boys and 90% of girls with NE fell into the NMNE category.

• Underreporting of Symptoms: A central finding is that 40% of patients/parents with NMNE did not initially report DVS. These symptoms were identified only through specific interrogation.
• Clinical Predictors of NMNE: Compared to MNE, NMNE was significantly associated with:
  • Female sex (OR 2.01).
  • Easier sleep arousal (scores ≤5; OR 1.74).
  • Incomplete defecation (OR 5.3).
  • Family history of DVS in childhood (OR 2.37).
  • Higher prevalence of nocturia, giggle incontinence, and urinary tract infections (UTIs) in females.
• Differentiation from Isolated DVS: Children with isolated DVS (no NE) differed from those with NE by having significantly easier sleep arousal (47% had scores of 1–2 vs. 7% in NE groups) and lower rates of habitual snoring and neuropsychiatric conditions.
• Pathophysiological Insights:
  • MNE: Dominated by impaired sleep arousal (69% had difficult arousal scores of 6–8).
  • NMNE: Associated with OAB markers (low bladder capacity, giggle incontinence) and easier arousal, suggesting that the inability to employ compensatory PTM during sleep leads to wetting despite a lower threshold for awakening.
  • Nocturia: Episodes of nocturia >1 per night or >7 per month were observed exclusively in NMNE and isolated DVS groups, never in MNE.

Significance and Claims
The paper asserts that the distinction between MNE and NMNE has profound therapeutic implications. The authors claim that the high prevalence of NMNE (84% in this cohort) is likely underreported due to the reliance on unstructured history taking. By failing to identify the 40% of NMNE cases where DVS are unreported, clinicians risk misdiagnosing OAB-driven NE as MNE.

The study concludes that:

1. Impaired arousal is the dominant pathogenic mechanism in MNE.
2. Overactive bladder plays a significant additional role in NMNE, often masked by compensatory behaviors.
3. Targeted Assessment: A high index of suspicion for unrecognized OAB is warranted, particularly in girls, children with easy sleep arousal, giggle incontinence, incomplete defecation, or a family history of DVS.
4. Clinical Practice: Systematic, detailed assessment of subtle daytime voiding symptoms is necessary to prevent misdiagnosis and to guide optimal therapy that addresses OAB (e.g., anticholinergics) rather than relying solely on MNE protocols.

The authors note limitations, including the retrospective design, potential referral bias, and the lack of objective measurements for nocturnal urine volume or functional bladder capacity. However, they emphasize that the study provides practical insights into the clinical identification of pathogenic mechanisms in NE.