What happens to the bladder at night? Overnight urodynamic monitoring in children with neurogenic vesical dysfunction

Purpose: We assess night and day function of the neuropathic bladder in chi ldren with neurogenic vesical dysfunction by overnight urodynamic monitorin g and conventional static cystometrogram. Overnight urodynamics as a diagno stic tool was evaluated and its reproducibility analyzed. Materials and Methods: In 18 months 3 boys and 3 girls 6 to 14 years old (m ean age plus or minus standard deviation 10.3 +/- 3.3) were studied prospec tively. Each child was evaluated on 4 separate occasions with 2-daytime cys tometrograms at a standard fill rate of 10 mi. per minute and 2 overnight u rodynamic studies for 8 hours using a Urolog Recorder.* All 6 children were interviewed regarding the acceptability, repeatability and compliance to o vernight urodynamics. Results: Bladder capacity was not significantly differnet during each episo de for either of the 2 tests. Mean bladder pressures in 2 children showed s table detrusor activity on cystometry (2 +/- 1.4 cm. H2O) and overnight uro dynamics (0.4 +/- 0.5, r = 0.9). Detrusor compliance was not impaired in th ese 2 children. Four patients had frank detrusor instability with a mean bl adder pressure of 50.6 +/- 17.4 cm. H2O on cystometry versus 35.9 +/- 5.2 o n overnight urodynamics (r = 0.9). Bladder compliance was severely impaired in these 4 patients. Compliance at potential bladder capacity for patient age was 6.6 +/- 2.1 ml./cm. H2O for cystometry versus 9.2 +/- 3.4 for overn ight urodynamics (p = 0.26, r = 0.9). Compliance at actual bladder capacity was 3.4 +/- 1.2 ml./cm. H2O for cystometry versus 3.8 +/- 0.8 for overnigh t urodynamics (p = 0.28, r = 0.9). There was good correlation between dayti me cystometry and overnight urodynamics (p <0.001, Pearson's coefficient co rrelation 0.92, 95% confidence interval 0.90 to 0.94). A K statistical anal ysis showed good agreement between cystometry and overnight urodynamics for stable bladder and frank detrusor instability (K = 0.9). Replicated measur ements of the same patient by the same observer had an error of variance of 1.7 cm. H2O with a narrow confidence interval, indicating the measurement error was small and that overnight urodynamics can be reproduced with relat ive accuracy within an individual. All 6 children preferred overnight urody namics to cystometry. Conclusions: There was good correlation between bladder behavior day and ni ght. Overnight urodynamics were accurate in predicting detrusor activity, a nd well tolerated and less embarrassing for a child with neurogenic vesical dysfunction.