Polysomnography and Autonomic Function Signatures of Nocturnal Enuresis: An Observational Study

Independent evaluation of overnight polysomnography and autonomic function in primary monosymptomatic nocturnal enuresis (PMNE) have produced variable results. The objective of this study was to simultaneously evaluate both to improve pathophysiological understanding with consequent therapeutic implications.

Five- to eighteen-year-olds with PMNE, presenting to a North Indian tertiary care teaching hospital (exclusion criteria: chronic systemic illness, intelligence quotient<70, and treated for PMNE in the last 6 months) were enrolled. Overnight polysomnography and autonomic function testing were preceded by Childhood and Adolescent Sleep Evaluation Questionnaire, Childhood behavior Checklist, and projective personality testing evaluations. Subsequently, they received standard behavioral therapy for 12 weeks.

Twenty-one cases were enrolled (10.6 ± 3.2 years, 16 boys). Impaired behavior was seen in 47.6% (majority inattention) and family/academics/self-esteem-related stressors were present in 42.9%. Sleep-related breathing disorder and sleep-related movement disorder (SRMD) were reported in 71.4% (15/21) and 61.9% (13/21), respectively. Cases had significantly lower sleep efficiency (72.3 ± 10.9% vs 80.6 ± 9.1%), higher proportion of N2 (76.4 ± 2% vs 63.1 ± 2.8%), and lower proportion of N3 (16.3 ± 1.7% vs 28.2 ± 1.5%) compared to controls. The diurnal median low frequency/high frequency variability was minimal (one [interquartile range (IQR):0.8-1.9] in sleep and 1.4 [IQR:0.5-2] while awake, P = 0.4). Median root mean square of successive differences was higher in sleep than awake state (81.04 ms [IQR:56.4-189.4] vs 60.6 ms ([QR:46-194.5], P = 0.5). One third responded favorably to standard behavioral therapy. Presence of other primary sleep disorders, particularly SRMD was significantly associated with poor response.

A dopamine depletion state with therapeutic implications can be speculated in PMNE, in those with impaired sleep and SRMD along with loss of diurnal sympathetic variation.