How long does the effect of botulinum toxin in neurogenic patients last? An analysis of the subset of "good responders".

[BACKGROUND] The aim of this study was to assess long-term efficacity of botulinum neurotoxin A (BoNT-A) in the treatment of neurogenic detrusor overactivity (NDO).

[MATERIALS AND METHODS] This was a retrospective monocentric study in a reference center. We included patients who received intradetrusor BoNT-A for NDO between 2001 and 2015. The focus of our analysis was on patients defined as "good responders" (≥ 5 injections of intradetrusor BoNT-A over a period of ≥5 years). The primary endpoint was the evaluation of long-term efficacity of BoNT-A. Recurrent NDO was monitored by the use of cystomanometry before the first injection and 1 month after each injection. The secondary objective was to assess the influence of NDO's etiology, age, and sex on the long-term efficacity of the treatment.

[RESULTS] A total of 107 patients were included (60.7% with spinal cord injury [SCI] and 36.4% with multiple sclerosis [MS]). The mean follow-up period was 83.7 months (66; 120). The mean number of injections was of 8.9 (5; 21). A total of 67.3% (n = 72) of patients were still controlled by treatment at the end of their follow-up period. Therapeutic failure occurred in 30 patients (26.1%) with a cessation of BoNT-A treatment at 76 months on average (median: 82.5 months). There was no significant impact of age (P = .42), sex (P = .35), or NDO's etiology (MS vs SCI; P = .54) on long-term efficacy of BoNT-A treatment.

[CONCLUSION] The results of our study indicate that the application of BoNT-A seems to be an effective and durable treatment in a large number of neurogenic patients after more than 10 years of follow-up. However, botulinum toxin tolerance occurred in approximately 25% of patients.