Introduction

For long, bladder augmentation has been considered as the gold standard treatment in neurogenic detrusor overactivity (NDO) patients who failed intradetrusor injections of botulinum toxin A (IDBTI). Several reinjections strategies have been described over the past few years (e.g. botulinum toxin switch, reinjection to a higher dosage,….) to avoid this last resort. Moreover, several studies have suggested that the optimal effectiveness of IDBTI could be obtained only after several injections. Patients with spina bifida are a high risk population regarding upper tract damage. There is currently no data regarding the management of failure of a first IDBTI in spina bifida patients. The aim of this study was to report the outcomes of botulinum toxin reinjections and to compare the outcomes of various reinjections strategies in patients with spinal dysraphism who failed a first IDBTI.

Methods

All patients with spinal dysraphism who had undergone at least one IDBTI from 2002 ro 2016 in 14 centers were included retrospectively. Patients below the age of 16 years old were excluded to focus on an adult population. The primary endpoint was the success of injections, defined as as the combination of urgency, urinary incontinence and detrusor overactivity resolution. The choice to perform either a repeat injection of the same toxin to the same dosage or a repeat injection of the same toxin to a higher dosage or a botulinum toxin switch or a bladder augmentation was left to the physician’s discretion. The outcomes of these various strategies were compared using the Fisher exact test.

Results

Out of a 125 patients cohort, 40 patients with spinal dysraphism who failed a first IDBTI were included (32%). Nine patients underwent augmentation cystoplasty directly after the first failed injection. At the end of the study period, two patients were lost to follow-up and two had just undergone their second IDBTI (outcomes not yet known). Out of 27 patients left, repeat injections remained uneffective in 17 patients (63%) despite one to four courses of reinjections. Two other patients had transient effectiveness before the injections failed again. Hence, 19 patients finally underwent bladder augmentation (70.4%). Thirteen patients had effective injections at least once during their management (48.1%) and 11 had still effective injections at the end of the study period (40.7%) but 3 of them were only improved without complete success (clinical but not urodynamic success). Thus only seven patients had a durable and satisfactory effectiveness of IDBTI (25.9%). Six botulinum toxin switch from onabotulinum toxin to abobotulinum toxin were performed with only two success (33%). In contrast, five out of six patients (83%) who underwent a repeat injection of onabotulinum toxin 300 U after failure of onabotulinum toxin 200 U had a complete success (difference: p=0.62). Finally, six out of 16 patients who underwent a repeat injection of onabotulinum toxin 200 U to the same dosage had a complete success (37.5%; difference with reinjection to a higher dosage: p=0.43). None of the patients in whom the first three injections failed finally responded to the toxin.

Conclusions

Reinjection strategies seem poorly effective in spina bifida patients who failed a first IDBTI with success in only 25.9% of them. _x000D_ Despite a lack of statistical power, reinjection of onabotulinum toxin to a higher dosage (300 U after failure of 200 U) seem to be the more effective option in these patients._x000D_

Funding

none