Need for botulinum toxin injection and bladder augmentation after isolated bladder outlet procedure in pediatric patients with myelomeningocele.
INTRODUCTION
In patients with neurogenic bladder outlet incompetence, a bladder outlet procedure (BOP) may be required to achieve urinary continence. However, when performed in isolation, a BOP can be associated with bladder deterioration and upper-tract injury. In the event of bladder deterioration, additional procedures such as bladder augmentation (BA) or botulinum toxin injection (BTI) may be pursued.


OBJECTIVE
The aim of this study was to assess long-term outcomes after isolated BOP in a pediatric myelomeningocele (MMC) population, including the need for additional surgical intervention in the form of BTI or BA.


MATERIALS AND METHODS
A retrospective cohort study was performed for patients with MMC who underwent an isolated BOP between 2004 and 2017. Primary outcomes included the need for postoperative BTI or BA. Secondary outcomes included the association between preoperative urodynamic parameters and need for BTI or BA.


RESULTS
BTI or BA was performed in 18 of 36 (50%) patients at a median of 17.8 months (IQR 11.2-29.3) after an isolated BOP. A median of 1 (IQR 1-3) BTI was performed in 11 (30.6%) patients. BA was performed in 9 (25%) patients, including 2 patients who previously underwent BTI. Patients who did not undergo BTI or BA after BOP had a slightly increased percentage estimated bladder capacity at the end of follow-up (107% versus 95%, p=0.42). By contrast, patients who underwent BTI or BA had a post-BOP percentage estimated bladder capacity that decreased from 112 to 70% (p < 0.001), increased maximum detrusor leak point pressure from 43 to 67 cm H2O (p = 0.01), and higher rate of de novo upper-tract changes. Unfortunately, no preoperative clinical, radiographic, or urodynamic factors predicted the need for BTI or BA.


DISCUSSION
On time-to-event analysis, the risk of BTI or BA was 53% at 5 years in our cohort. Risk of these procedures was highest in the first two years after BOP. 9 of 11 (82%) patients who underwent BTI had improvement in bladder dynamics and BA was not pursued. These findings suggest that BTI provides a less-morbid alternative to BA in patients with MMC and de novo adverse bladder storage changes after an isolated BOP.


CONCLUSION
The need for BTI or BA after an isolated BOP is significant in patients with MMC. BTI offers a less-invasive alternative to BA in this population.