Botulinum Toxin (BTX-A)

The Injection of botulinum toxin A into the detrusor muscle has been under study for several years for a variety of bladder disorders. Under anesthesia, a patient may receive 20 to 30 injections of botox in various locations in the bladder. Numerous studies have been conducted though only four of the more rigorous randomized trials.

Researchers at the University of Rochester (NY) studied 22 patients with OAB-incontinence who were non responsive to anticholinergic therapy. The detrusor was injected at 8-10 sites in varying dosages and placebo. Statistically significant improvements in daily incontinence episodes and quality of life questionnaires were seen in the botulinum-A toxin group with no changes in the placebo group. In a review of their early data, no change was seen in nocturia, daily voiding frequency, peak flow or detrusor pressure. The authors concluded that botox inuections can significantly reduce incontinence episodes. They do cite, however, a risk of urinary retention that may require self-catheterization after treatment. (7)

Researchers in France conducted a five year randomised, double-blind placebo-controlled trial of 99 patients who received a single treatment of 100u or 150u BoNTA. At three months after treatment, they “observed a >50% improvement versus baseline in urgency and urge urinary incontinence (UUI) in 65% and 56% of patients who respectively received 100U (p=0.086) and 150U (p=0.261) BoNTA injections and >75% improvement in 40% of patients of both groups (100U [p=0.058] and 150U [p=0.022]). Complete continence was observed in 55% and 50% patients after 100U and 150U BoNTA treatment, respectively, at month 3.” Quality of life and frequency showed sustained improvement at the six month visit. (8)

Researchers in Portugal studied the efficacy and safety of botox on patients struggling with incontinence due to multiple sclerosis or spinal cord injury. Patients received 30 injections of either 200u, 300u or placebo. Results occurred at week two and had increased significantly by week six. Improvements were seen in detrusor contraction via and a dramatic decrease incontinence episodes. Prior to the study, patients had an average of 33.5 incontinence episodes which had reduced -21.8 (200u) and -19.4 (300u).(9)

British researchers studied the quality of life of patients with multiple sclerosis and OAB in a prospective study involving 137 patients treated with repeated detrusor injections of botulinum type A. Before treatment 83% of the patients were incontinent; 4 weeks after the first treatment, 76% were completely dry. The median interval between retreatments was 12-13 months. (10)

As mentioned in the Univ. of Rochester study, one risk is the development of urinary retention. Patients who undergo Botox treatment should first be evaluated for their ability to self-catheterize, should the need arise.


  • (7) Flynn MK, et al. Outcome of a randomized, double-blind, placebo controlled trial of botulinum A toxin for refractory overactive bladder. J Urol. 2009 Jun;181(6):2608-15.
  • (8) Denys P, et al. Efficacy and Safety of Low Doses of Botulinum Toxin Type A for the Treatment of Refractory Idiopathic Overactive Bladder: A Multicentre, Double-Blind, Randomised, Placebo-Controlled Dose-Ranging Study. Eur Urol. 2011 Oct 25.
  • (9) Cruz F, et al. Efficacy and safety of onabotulinumtoxinA in patients with urinary incontinence due to neurogenic detrusor overactivity: a randomised, double-blind, placebo-controlled trial. Eur Urol. 2011 Oct;60(4):742-50.
  • (10) Khan S, , et al. Long-term effect on quality of life of repeat detrusor injections of botulinum neurotoxin-a for detrusor overactivity in patients with multiple sclerosis. J Urol. Apr 2011;185(4):1344-9