Application of urethral injection of calcium hydroxyapatite as a natural bulking agent for improvement of urinary incontinence in children with spinal dysraphism

Purpose The aim of this report is to evaluate the efficacy of endoscopic injection of calcium hydroxyapatite (CaHA) into the bladder neck and posterior urethra in children with refractory urinary incontinence due to spinal dysraphism. Methods A retrospective study was performed on patients with neuropathic bladder due to spinal dysraphism who had undergone submucosal urethral injections of CaHA from 2010 until 2019. All patients were totally incontinent without voiding per urethra and did not respond to 1-year standard pharmacotherapy with anticholinergic drugs. All children underwent a precise physical exam and urodynamic studies. Patients underwent urethrocystoscopy and injection of pure soluble CaHA into the bladder neck and posterior urethra except for the verumontanum. The outcomes were determined as no change, improvement (social continent), or cure (total continent). Results Fifteen children (ten boys, five girls, mean age of 7.6 years) with a history of spinal dysraphism and refractory urinary incontinence were included. Endoscopic injections of CaHA were performed one or two times for each patient. At the median follow-up of 2 years (interquartile range = 6), seven (46.7%), three (20.0%), and five (33.3%) of the patients were total continent, social continent, and total incontinent, respectively. In four patients, intradetrusor botulinum toxin injection was performed simultaneously with CaHA injection. Also, one patient experienced a febrile urinary tract infection between two CaHA injections. Among 15 patients, 9 had atonic/hypotonic bladders both before and after CaHA injections; at the last follow-up, 4 of these children (44.4%) were totally continent. No injection-related or other complications were observed in the patients. Conclusion Injection of CaHA into the bladder neck is relatively safe, reproducible, and effective for total dribbling urinary incontinence in children with spinal dysraphism. The bladder neck reconstruction with or without a urethral sling or other surgical procedures could be postponed until puberty in selected cases. However, further multicenter clinical trials are highly recommended.