Two-year efficacy and safety of botulinum a toxin intravesical injections in patients affected by refractory painful bladder syndrome

Introduction and Aim: We report the 2-year efficacy and tolerability of intravesical botulinum A toxin (BoNT/A) injections in patients with painful bladder syndrome (PBS) associated with increased urinary frequency refractory to conventional treatments. Materials and Methods: Thirteen women were prospectively included in the study. The preliminary assessment included voiding diary, urodynamics, urinary tract ultrasound and the visual analog scale (VAS) for pain quantification. All patients received multiple injections of 200 U commercially available BoNT/A diluted in 20 ml 0.9% NaCl, under cystoscopic guidance. Clinical evaluation, urodynamics, urinary tract ultrasound and VAS were repeated at least two times per year throughout the follow-up. Results: A total of 58 injections were administered with a mean of 4.8 ± 0.8 injections per patient. The mean interval between two consecutive injections was 5.25 ± 0.75 months. At 1 and 4 mo follow up ten patients reported a subjective improvement. Mean VAS scores, mean daytime and night-time urinary frequency decreased significantly. Nine patients at 1 month and seven at the 4-month check-up complained of dysuria. The three non-responders to the first intravesical treatment session underwent another three months later with satisfactory results. At 1 and 2 years follow up the beneficial effects persisted in all patients. We did not observe any systemic side effects during the observation time. Conclusions: Intravesically injected BoNT/A is effective and safe in the medium-term management of patients with PBS. As the beneficial effect decreased progressively within a few months after treatment, repeat injections of the neurotoxin were needed over time.