Endoscopic Botulinum Toxin Injection for Refractory Enuresis Based on Urodynamic Assessment

PURPOSE: This study aimed to determine the urodynamic characteristics of refractory enuresis and explored whether those characteristics can be managed through differential endoscopic injections with botulinum toxin. METHODS: In total, 27 patients with nonmonosymptomatic enuresis who showed no response after conservative treatment for more than 12 months were included. The patients then underwent a videourodynamic study and received a differential endoscopic injection of botulinum toxin on the same day. Reduced capacity, detrusor overactivity, and bladder neck widening were the 3 major abnormal findings assessed during the filling phase, while sphincter hyperactivity was the only abnormality assessed during the emptying phase. An intravesical or intrasphincteric injection of botulinum toxin was attempted according to the videourodynamic study findings. Follow-up was conducted at 1, 3, 6, and 12 months after treatment. RESULTS: The median age was 10 years (range, 7–31 years). Although 19 and 8 patients had a preoperative diagnosis of overactive bladder or dysfunctional voiding, respectively, the urodynamic diagnosis was different in more than half of the patients. Those showing detrusor overactivity benefited from intravesical botulinum toxin injection, whereas those with only sphincter hyperactivity benefited from both intravesical and intrasphincteric injections. Treatment resistance to botulinum toxin seemed to be attributable to bladder neck widening. Time had no apparent effect on efficacy, which persisted 6 months after the injection. More than 80% of the patients maintained the benefits of the injection after 1 year. CONCLUSIONS: Videourodynamic studies were useful for identifying the reasons underlying refractory nonmonosymptomatic enuresis and helpful for determining the appropriate site of botulinum toxin injection.