Botulinum toxin in patients at-risk for bladder augmentation: Durable impact or kicking the can?

Deferring bladder augmentation (BA) may be desirable in a pediatric neurogenic bladder (NGB) with worsening compliance, but prior studies have questioned whether onabotulinum toxin A (BTX) demonstrates durable improvement in compliance. We present our overall experience with BTX and its role in mitigating the "at-risk" NGB, as determined by urodynamic characteristics.

A retrospective single-institution review of all BTX procedures performed during January 2010 to October 2018 was conducted. Patients with <12 months follow-up after first BTX injection were excluded. Urodynamic studies (UDS) were reviewed to assign National Spina Bifida Patient Registry (NSBPR) as well as institutionally developed (LCH) risk classification groups. Patients were considered "at-risk" for BA if they had any of the following: NSBPR risk grade of intermediate or hostile; LCH risk grades indicating end-fill pressure >25 cmH₂ O or detrusor sphincter dyssynergia (DSD); upper tract changes including new hydronephrosis; new or worsening vesicoureteral reflux; or other signs of a hostile urinary tract (i.e., febrile UTIs). UDS risk grades pre and post-first BTX injection were compared in this "at-risk" group, when available.

Thirty-nine patients underwent 162 injection procedures over a median follow-up of 65 months interquartile range (IQR 49-81). Median age at first BTX was 10 years and the median number of BTX injections per patient was 4 (IQR 2-7; range 1-12) with a median time of 6 months between injections (IQR 4-10). Twenty-six patients were deemed "at-risk" at the time of first BTX injection, and of those, 16 (61.5%) proceeded to BA at a median of 36 months (IQR 22.5-42). A small number (four) had BA due to upper tract changes or worsening pressures on BTX, while nine patients (five with CKD) proceeded to BA given a lack of sufficient improvement to consider BTX a long-term viable option. Post-first BTX UDS demonstrated downgrading of risk group in 38% and 63% using NSBPR and LCH classifications, respectively.

Encouraging improvements in the urodynamic risk group were noted in some patients. With careful counseling and follow-up, BTX may safely extend the time to BA in some "at-risk" patients.