To discuss the urodynamics differences in children of neurogenic bladder(NB) with vesicoureteral reflux(VUR) when with or without detrusor overactivity, for the clinical treatment of such patients to provide a theoretical basis for reference.

Selecting 204 cases of children with NB vesicoureteral reflux(VUR) by video-urodynamics(VUDS) from 2017-2019, 90 males and 144 females, aged 5-12 years, mean 8.5 years.According to the filling phase whether or not presence of detrusor overactivity(DO), it can be divided into detrusor overactivity group (n=60) and DO absence group (n =144).Observation records were carried out when the bladder ureter reflux during perfusion of bladder ,like bladder safety capacity ,detrusor pressure and calculate the bladder compliance when the reflux occurs in the two groups. 
Record the maximum cystometry capacity(MCC), maximum detrusor pressure and calculates the bladder compliance at the end of filling in the two groups. 
According to the reflux flow level ,it will be divided into mild reflux (Ⅰ-Ⅱ degrees), severe reflux (Ⅲ-Ⅴ degrees), then we analyse the differences of the two groups like reflux side (single or double)and reflux degree.

①When the VUR occurred,in DO group the bladder safety capacity and compliance were 96.5±14.1ml,5.3±1.8ml/cmH2O, while in DO absence group the bladder capacity and compliance were128.8±30.7ml, 7.9±2.0ml/cmH2O,respectively.Statistical difference existed between the two groups(P <0.05).
②When the VUR occurred,the detrusor pressure in DO group and DO absence group was 27.3±5.1cmH2O,26.1±6.4cmH2O, respectively (P＞0.05).
At the end of filling phase, the detrusor pressure in DO group and DO absence group was 38.8±7.6cmH2O,37.9±8.2cmH2O, respectively. The detrusor pressure difference when VUR occurred and end of filling phase between the two groups were not statistically significant,respectively(P＞0.05).
③At the end of filling phase, the MCC and bladder compliance in DO group were (183.5±33.6ml, 5.1±1.9ml/cmH2O),comparing with DO absence group,the data of MCC and bladder compliance were larger(235.7±35.9ml, 7.5±1.3ml/cmH2O), having significant difference,respectively(P <0.05). 
④The DO group of 36 cases have unilateral ureteral reflux(60%), bilateral reflux in 24 cases (40%).While the DO absence group of 48 cases have unilateral reflux (33%), 96 cases have bilateral reflux (67%). The severity of VUR was obvious in both groups,and there were no statistically significant differences in kidney function and serum creatinine between the two groups(P＞0.05).

VUR is one of the most common complications of NB in children. If not treated promptly, VUR can cause hydronephrosis and upper urinary tract infection, and even eventually lead to kidney failure.Detrusor overactivity (DO) is an involuntary contraction of the detrusor during bladder filling.Neurogenic detrusor overactivity (NDO), along with part of NB children, can lead to complications such as voiding incontinence, VUR and damage to the upper urinary tract[1].
    Video- urodynamics can observe VUR during filling and urine storage and simultaneously record changes in bladder and detrusor pressure during reflux, and continuously monitor changes in bladder morphology and VUR level.When they appear VUR, we need to record, bladder detrusor pressure filling capacity, and the formula BC = ΔV/ΔP, to calculate the bladder compliance.When the children had leakage or a strong desire to void, the perfusion was stopped, detrusor pressure and bladder perfusion were recorded, and the bladder compliance at the end of filling was calculated.According to the international flow classification standard, VUR severity can be divided into mild reflux (Ⅰ-Ⅱ degrees), severe reflux (Ⅲ-Ⅴdegrees), in the process of the bladder filling, we observe and record which side VUR occurred and the level[2].
    In 1983, McGuire[3]proposed that for children with NB, the urine leakage point pressure of detrusor over 40cmH2O is closely related to the incidence of upper urinary tract damage.The bladder volume with bladder pressure ≤40cmH2O in the filling phase is the bladder safety capacity.In this study, the detrusor muscle depression of VUR was lower than 40cmH2O in the two groups, indicating that the VUR occurred at a lower detrusor pressure in the two groups.It was considered that the structure of the connection of bladder and end of ureter in NB children probably was not perfect.In this study, we found that VUR was likely to occur in children with DO with less bladder volume, meaning that reflux may occur earlier and bladder compliance is poor.This suggests that for the treatment of NB children with DO, while relieving the frequency, urgency and incontinence caused by DO, it may also help to protect the upper urinary tract function.

For NB children with VUR, when it occur DO,the urodynamic characteristics are those the bladder safety capacity and MCC have the lower level, along with poor bladder compliance at the same time.

Javadi Larijani F, Moghtaderi M, Hajizadeh N, et al. Preventing Kidney Injury in Children with Neurogenic Bladder Dysfunction[J]. 2013, 4(12):1359-1364.
Nordenström Josefin,Sjöström Sofia,Sillén Ulla et al. The Swedish infant high-grade reflux trial: UTI and renal damage.[J] .J Pediatr Urol, 2017, 13: 146-154.
McGuire EJ, Woodside JR, Borden TA. Upper urinary tract deterioration in patients with myelodysplasia and detrusor hypertonia: a followup study. J Urol.1983 Apr;129(4):823-6.