New Technology for Refractory Overactive Bladder Improves Outcomes

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Massachusetts General Hospital now offers a new sacral neuromodulation system as a leading-edge surgical implant treatment for refractory overactive bladder (OAB). While sacral neuromodulation for OAB is not new (nor are third-line treatments such as botulinum toxin), this next-generation implant is more user-friendly and longer-lasting with fewer contraindications, says Ajay Singla, MD, a urologist at Mass General and director of the Harvard Urologic Surgery Residency Program. Dr. Singla brought the new technology to Mass General shortly after the FDA approved it in late 2019, and has completed a total of five implants thus far.

Millions of Americans are affected by OAB, a symptom complex characterized by urinary urgency with or without urge incontinence, usually with frequency and nocturia. These issues often lead to intangible symptoms of embarrassment, loss of productivity and overall diminished quality of life.

"Leakage can be very disturbing and devastating to patients," says Dr. Singla.

Bladder Pacemakers and Limitations of Previous Technology

Overactive bladder can be caused by weak muscles, nerve damage, obesity or the use of medications, alcohol or caffeine. First-line treatment for OAB includes behavior modification, with bladder training and pelvic floor exercises, scheduled voiding and diet and fluid intake changes. If symptoms do not improve, the second-line treatment is a trial of at least two medications.

"If the medications don't work, that's when we call this refractory overactive bladder," says Dr. Singla. Third-line treatments for refractory OAB include sacral neuromodulation.

Sacral neuromodulation implants, also known as "bladder pacemakers," attempt to modulate spinal and brain control of the bladder using electrical nerve stimulation.

"We place a lead into the third sacral nerve root (S3) and stimulate it with a battery implanted in the buttocks area," says Dr. Singla. "It is called neuromodulation because it modulates the nerve to change the bladder behavior and slow down the bladder muscle." With a remote control, the patient can adjust the amplitude as needed.

Since 1997, sacral neuromodulation for refractory overactive bladder has proven to be an effective treatment, but not without limitations, including:

• Battery life of only five years
• Frequent office visits for reprogramming
• Contraindication for a full-body MRI because of metal in the lead tip
• Pain from the implanted battery

Sacral neuromodulation also provides relief for urinary retention and bowel incontinence.

System Improves Patient Experience and Outcomes

Dr. Singla reports that this new technology overcomes the previous technology's shortcomings with:

• A lifespan of at least 15 years
• Constant current stimulation that automatically compensates for tissue changes without the frequent need for patient adjustment
• No metal in the tined lead, which allows for full-body MRI
• More comfort from a smaller battery (slightly larger than a quarter)
• Convenience from a rechargeable battery

"The patient wears a small belt with a recharger located near the battery in the buttocks," says Dr. Singla. "In about half an hour, the battery recharges wirelessly, and the patient is good to go for another month or two."

Clinical results of one such system, published in Neurourology Urodynamics, show that at one year, 89% of patients experienced at least a 50% reduction in urinary urgency incontinence symptoms.

Dr. Singla implements the technology in two stages. He first places the lead and connects it to an external generator or battery source.

"With this trial, the patient records their experiences for two weeks," he says. "If we see at least a 50% improvement in symptoms, then I am confident in its efficacy and complete the second stage of permanent implantation of the battery."

Protocol for Considering Sacral Neuromodulation

If first- and second-line treatments for OAB fail, Dr. Singla recommends referral to a specialist for evaluation, including a urodynamic test to confirm OAB. After that, Dr. Singla says the specialist will discuss with the patient the pros and cons of third-line treatment options, including:

• Botox injections in the bladder muscle
• Posterior tibial nerve stimulation (PTNS), which stimulates the nerve at the ankle instead of the back
• Sacral neuromodulation

"Botox injections are effective, but they last only nine to 12 months," says Dr. Singla. "If the patient needs injections every year for 20, 30 or 40 years, that is a lot of medication to keep symptoms under control versus a one-time implantation." Likewise, he says PTNS requires 12 sessions to stimulate the nerve and produce the same effect as central stimulation from sacral neuromodulation.

Sacral neuromodulation is contraindicated for patients with underlying neurogenic pathology like multiple sclerosis, Parkinson's disease, stroke or spinal cord injury. Patients who cannot operate the wireless remote control are also not candidates for this procedure.

Developments for Third-Line Management of Refractory OAB

Dr. Singla reports that additional technologies with rechargeable batteries are on the horizon and that trials are currently underway for a rechargeable battery for PTNS. "These developments, along with our new system, are exciting for our patients with refractory OAB."

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