Botulinum injections show efficacy in refractory OAB

Zürich Switzerland-Botulinum toxin A (Botox) may be an effective, safe alternative treatment option in patients experiencing overactive bladder refractory to more standard treatments, according to a study performed at the Universitätsspital Zürich and Kantonsspital Luzern, Switzerland.

One hundred patients, ranging in age from 29 to 82 years, who were diagnosed with non-neurogenic overactive bladder (urgency-frequency syndrome) and incontinence that did not respond to treatment with anticholinergic drugs and physiotherapy were injected with 100 units of botulinum toxin A at 20 sites in the detrusor muscle under cystoscopic control.

Prior to initiating treatment, data on urodynamics, neurologic status, urine probes, bladder biopsies, and patients' micturition diaries were collected and analyzed. Clinical and urodynamic follow-up visits were held 6 to 8 weeks after treatment.

"Eighty-eight percent of [these] patients with overactive bladder showed improvement [p=.001] of bladder function with respect to subjective symptoms as well as to urodynamic parameters," lead author Daniel M. Schmid, Jr, MD, of the department of urology, Universitätsspital Zürich Switzerland, told Urology Times.

Dramatic improvements seen

Within 14 days of the treatment, 82% of the patients reported that urgency completely disappeared, 86% regained continence, nocturia episodes fell by 50%, and urinary frequency decreased by 50%. Urodynamic gains included increased maximum bladder capacity from a mean of 246 mL to a mean of 381 mL, improved detrusor compliance (from 24 mL/cm of water to 41 mL/cm), increased initial urge volume (from a mean of 126 mL to a mean of 212 mL), and increased urge volume from 214 mL to 309 mL.

The authors noted that pretreatment detrusor instability (reflex volume of 169 mL) dissolved in 77% of patients. Maximum efficacy was reached at 3 months; duration of efficacy was approximately 9 months. Thereafter, urodynamic parameters generally did not meet baseline volumes.

"Botulinum toxin A appears not only to block neuromuscular transmission of acetylcholine, but it seems also to modulate bladder reflexes and block transmission of ureteral afferent nerves," Dr. Schmid said.

No severe side effects were reported. Side effects consisted of four cases of temporary urinary retention (resolved by self-catheterization) and 10 urinary tract infections. Eight patients reported poor clinical benefit, and analysis indicated that detrusor compliance in these patients was very low even before surgery.

"Botox injections into the detrusor muscle appear to be an efficient, safe treatment option, not only in spinal cord-injured patients with detrusor hyperreflexia [as shown in J Urol 2000; 164:692-7; N Engl J Med 2000; 342:665], but also in patients suffering from severe, non-neurogenic overactive bladder [that is] resistant to all conventional treatment," Dr. Schmid concluded.