Newer incontinence treatments raise hope, questions

August 15, 2008

Studies that looked at botulinum-A toxin for overactive bladder, studies of the transobturator male sling, and an investigation of stem cell injections for stress urinary incontinence all show promise, but all raise important clinical questions.

Key Points

These studies and a study about whether to install a sling during pelvic organ prolapse repair or to do so in the event of incontinence were selected by Dr. Raz as noteworthy presentations from this year's AUA annual meeting.

The average duration of efficacy of intravesical botulinum toxin A for refractory overactive bladder is 6 to 8 months. Repeat botulinum injections seemed safe, and re-treatment showed no diminution in efficacy.

"The results are promising and encouraging," Dr. Raz told Urology Times. "The treatment appears to be safe, and there appears to be no diminution of efficacy, but we need further comparative study to confirm those findings."

He added that these studies should be prospective, randomized, comparative trials and should define the duration of efficacy, dosages, and injection sites, as well as which patients are most likely to respond to the treatment.

Children in whom botulinum toxin A therapy failed had antibodies to the bacterium, suggesting immune mediation of treatment failure.

This study of 12 patients with neurogenic bladders found that two of six patients who were refractory to treatment had developed antibodies to the toxin.

"This is an important finding that needs to be confirmed," Dr. Raz said. "If it occurs, repeat injections may fail in an undetermined number of patients."

He recommended that studies of immune response be part of all future trials using the agent.

Studies showed conflicting results for transobturator slings used for men with urinary incontinence. In one study, 29% of men suffered severe perineal pain, and only 17% used no more pads, but in another, 86% of patients were dry.

"History appears to be repeating itself," said Dr. Raz, explaining that a passive compression technology was developed in the 1980s. Initial studies suggested that the device was effective, but long-term studies showed that only about 30% of patients remained dry.

"I don't believe we have the final word," he said. "We need to know the long-term effect of passive compression devices. We have very early data. I am concerned with 29% of patients being in serious pain and only 17% being dry."

In 2-year follow-up of ultrasound-guided injection of autologous myoblasts for stress incontinence, pad use for women dropped from 6 to 1 per day, and 63% used no more pads. In men, pad use dropped from 4.9 per day to 1.6 per day, and 28% of patients used no more pads. Imaging showed functional recovery of the external urethral sphincter in both groups.

These data suggest that injections of muscle-derived stem cells appear to be effective in treating stress or mixed urinary incontinence, but little is known about how and why the procedure works.

The research, by a team from Innsbruck, Austria, raises more questions than it answers, Dr. Raz said. The cells were drawn from upper arm muscles and grown in the lab. A specially designed device was used to inject the fibroblasts into the urethral submucosa, and the myoblasts into the rhabdosphincter to reconstruct the muscle. The injections were made under ultrasound guidance, another innovation.