Sleep fragmentation and periodic limb movements in children with monosymptomatic nocturnal enuresis and polyuria

Children with nocturnal enuresis (NE) have been found to have sleep fragmentation and a high incidence of periodic limb movements in sleep (PLMS). This study explored the association of monosymptomatic NE and polyuria in relation to fluid intake, bladder volume, number of wet nights, and number of nights with polyuria to the frequency of PLMS and cortical arousals during sleep. Thirty children with monosymptomatic NE and polyuria were enrolled in the study. Enuretic parameters were determined by diaries, forced drinking, uroflow, and ultrasound examination. All subjects participated in one polysomnographic study. The number of cortical arousals and PLMS were compared with those recorded in a former pilot study which included only children with refractory NE. Of the 30 children who participated in the study, the mean age was 10.43 +/- 3.08 (range 6-16) years, and 23 were boys. The PLMS index was positively associated with the arousal index and the awakening index (p < 0.001). No significant association between the sleep and the enuretic parameters was found. Children with refractory NE showed a significantly higher PLMS index (p < 0.001). We found that PLMS and cortical arousals in sleep were increased in children with monosymptomatic NE and polyuria, without a significant association with the enuretic parameters. These observations suggest the presence of a comorbid mechanism driven by a common, independent pacemaker. We hypothesize the autonomic system, its sympathetic branch, and the dopaminergic system as candidates for this pacemaker.