Efficacy and safety of botulinum toxin a injection into urethral sphincter for underactive bladder

The aim of this retrospective study was to evaluate the clinical efficacy and safety of botulinum toxin type A (BTX-A) injection into the urethral sphincter to treat patients with underactive bladder (UAB).

From September 2012 to December 2018, 35 patients with UAB who presented with dysuria were treated with BTX-A (Prosigne®, Lanzhou Biological Products, Lanzhou, China). All patients were evaluated using the International Continence Society standard for video-urodynamic examination before and 1 month after treatment. The index includes maximum urinary flow rate, detrusor leak point pressure, and maximum urethral pressure. Post-voiding residual urine volume was measured using ultrasound before, one and 3 months post injection.

After 1 month of treatment, the maximum flow rate increased from 2.5 ± 1.1 ml/s to 6.6 ± 1.7 ml/s (P < 0. 05). The maximum urethral pressure decreased from 73.5 ± 5.8 cmH₂o to 45.6 ± 4.3cmH₂O (P < 0. 05). The detrusor leak point pressure decreased from 69.9 ± 20.7cmH₂O to 26.3 ± 7.4cmH₂O (P < 0. 01). Post-voiding residual urine decreased from 282.8 ± 134.2 ml to 125.0 ± 92.1 ml (P < 0. 01) but increased to 270.1 ± 129.0 ml 3 months post injection. Of the 35 patients, 57.1% (20/35) relied on clean intermittent catheterization (CIC) before injection, but 75.0% (15/20) of them could partly void 1 month after injection, and 25%(5/20) could void without CIC. Eight patients showed hydronephrosis before treatment; in three of them, hydronephrosis decreased slightly, while it resolved in two. All patients were followed for three to 6 months, and the effect lasted for about two to 3 months. No serious adverse events occurred in any patient.

The results suggest that Prosigne® injection into the urethral sphincter is an effective, safe, and inexpensive way to treat UAB.