Objective: We investigated the effect of botulinum-a toxin injections into the detrusor and external sphincter muscle in patients with overactive bladder (OAB) symptoms.
Methods: We included 44 patients - 41 women and three men with a mean age of 66.1 years - who were suffering from OAB symptoms that were refractory to anticholinergic treatment. We injected 200-300 U of BTX-A (Botox) into the detrusor muscle; 22 patients also received external sphincter injections. For outcome analysis, we used a bladder diary, a urodynamic examination, and a questionnaire that consisted of 27 validated questions.
Results: Changes in the bladder diary 4 weeks and 3, 6, and 9 months after BTX-A injection were as follows: Micturition frequency was reduced by 12%, 16%, 13% and 9%, respectively. Average pad use decreased from 4.2 pads per day to at most 2.4 pads per day after 6 months. Urodynamic changes were most distinct after 4 weeks: the volume when the first uninhibited detrusor contraction occurred increased from 149+/-18.2 mL to 263 +/- 24.2 mL, and maximum cystometric bladder capacity increased from 228 +/- 19.2 mL to 305 +/- 19.0 mL. Subjectively, 86% of the patients would choose this procedure for their bladder condition again. Residua 4 weeks after additional injection into the sphincter muscle were distinctly smaller than in the "only detrusor" group.
Conclusions: BTX-A detrusor and sphincter injection is very effective in treating OAB symptoms. For patients who might be expected to have residual urine after injection only into the detrusor, additional injection of low doses of BTX-A into the external sphincter muscle could be one option to reduce that risk.