Idiopathic overactive bladder (IOAB) is a common symptom of lower urinary tract dysfunction in children, which seriously affects the health of patients. Intravesical injection of botulinum toxin type A (BTX-A) is a minimally invasive alternative therapy for children with small bladder capacity or detrusor overactivity who fail to respond to drug therapy. However, BTX-A’s safety, efficacy, and possible influencing factors for children still need to be further studied.

This study was made on 54 children with IOAB (average age, 11.8±4.4 years), including 24 males (44.4%) and 30 females (55.6%). Urotherapy and drug treatments were ineffective in all children, who then received intravesical injections of BTX-A. The urodynamics (UDS) examination was performed at 1 week before treatment and 3 months after treatment, and the overactive bladder symptom score (OABSS) and incontinence specific quality of life (I-QOL) were collected. Perioperative and postoperative adverse events were also recorded. A global response assessment (GRA) score of ≥2 at 3 months postoperatively was defined as an effective treatment. Patients were divided into the effective group and the ineffective group to explore possible influencing factors factors affecting the outcome of BTX-A treatment, such as age, gender, and preoperative urodynamic parameters. An effective case is defined as the GRA score ≥ 2, and at the same time meeting at least one of the following objective improvement criteria: (1) The OABSS score decreased by ≥ 3; (2) The number of urinary incontinence episodes in 24 hours decreased by ≥ 50%; (3) The DLPP decreased to < 40 cmH2O. The ineffective group consists of those who do not meet the above criteria or whose condition worsens.

The bladder compliance (BC), bladder capacity ratio (BCR, measured/expected bladder capacity), OABSS score, and I-QOL score of patients significantly improved after BTX-A injection (all P<0.05). 70.4% of the patients (38/54) were satisfied with BTX-A treatment. The main adverse event during the follow-up was a temporary increase in post-void residual (PVR) volume after injecting BTX-A (19/54, 35.2%), which was alleviated by the Crede action or clean intermittent catheterization. In group study, there was significant difference in age [13.18 + 4.34 years vs. 8.56 + 2.58 years, t = 2.383], preoperative BC [17.18 + 13.51 mL/cmH2O vs. 5.20 + 3.86 mL/cmH2O, t = 3.470], and preoperative detrusor Leak Point Pressures (DLPP) [27.08 + 9.76 cmH2O vs. 49.56 + 36.38 cmH2O, t = -3.558] between effective group (38/54, 70.3%) and ineffective group (16/54, 29.6%) (P<0.05). The differences in preoperative BCR, PVR, voiding efficiency, and gender were not statistically significant between the two groups (P>0.05).

The findings demonstrate that BTX-A injection significantly improves urodynamic parameters (bladder compliance and bladder capacity ratio), clinical symptoms (OABSS), and quality of life (I-QOL) in pediatric patients with bladder dysfunction. The high satisfaction rate (70.4%) supports its clinical utility. Although a transient increase in post-void residual occurred in over one-third of patients, it was manageable with adjunctive maneuvers, indicating an acceptable safety profile. Comparative analysis between the effective and ineffective groups suggests that older age, higher preoperative bladder compliance, and lower preoperative detrusor leak point pressure are associated with better treatment response. These factors may serve as predictors of therapeutic efficacy, highlighting the importance of patient selection in optimizing outcomes following BTX-A intervention.

Intravesical injection of BTX-A is a safe and effective treatment for most of children with refractory IOAB. Young age, poor BC, and high DLPP at treatment are associated with poor prognosis of BTX-A treatment.