Management of the overactive bladder patient can be challenging due to refractory symptoms, patient expectations and the complex pathophysiology, but we continue to improve our therapies to better meet patients’ needs. The 2019 AUA guidelines on overactive bladder recommend first line therapy as behavioral modification followed by pharmacotherapy as second line treatment options.^1,2 Neuromodulation in the forms of posterior tibial nerve stimulation, onabotulinum toxinA, and sacral neuromodulation are the recommended third line options. Since the U.S. Food and Drug Administration (FDA) approval of Medtronic InterStim™ in 1997 for urge urinary incontinence and its 1999 approval for urinary frequency, urgency and nonobstructive urinary retention there has been incremental innovation in the field including the InterStim IITM Internal Pulse Generator, the tined lead and optimal lead placement technique, as well as expanded knowledge and clinical data. Breakthrough years for sacral neuromodulation were 2019 and 2020 as the FDA approved new technologies including smaller implantable rechargeable stimulators and magnetic resonance imaging (MRI)-safe devices. These have increased the options for providers and patients. With the advent of these advances, how do patients and surgeons make the more appropriate choice?

With the FDA approval of the Axonics™ Sacral Neuromodulation System in 2019 there are now 2 approved sacral neuromodulation treatment options in the United States and Europe. The Axonics device is currently advocated for in the 2020 NICE (National Institute for Health and Care Excellence) guidelines as the treatment of choice for refractory overactive bladder in Europe partly due to the cost modelling of a 15-year battery.³ At this time, Axonics offers a rechargeable-only battery option (5 cm³) with a constant current technology. Achieving a battery life of 15 years, the Axonics device has demonstrated significant safety and efficacy in the treatment of overactive bladder.^4,5 Axonics has filed a premarket approval for a nonrechargeable option, a primary cell battery

Medtronic InterStim offers both rechargeable and nonrechargeable battery options. The InterStim II device approved in 2011 is a recharge-free, constant voltage driven battery. Its lithium ion battery averages a 7-year life expectancy. Five-year clinical efficacy and quality of life improvements have been reported in patients with overactive bladder, fecal incontinence and urinary retention with the InterStim device.⁶ The InterStim Micro™ system approved in 2020 has a smaller rechargeable battery with a lithium titanate cell. This 2.8 cm³ battery has a rechargeable capacity of 15 years with no battery fade.⁷

MRI compatibility for InterStim II and InterStim Micro with the InterStim SureScan™ lead is conditionally safe for full-body MRI scan with Tesla 1.5 and 3.1 MRI scanners. The Axonics system is also conditionally safe for full-body and head Tesla 1.5 and 3 MRI scanners. An impedance check is required for the Axonics device prior to full-body MRI scans,^8,9 but not for InterStim devices. If there is an abnormal impedance detected on an Axonics device then MRI imaging is not recommended.

Rechargeable versus nonrechargeable batteries has become a discussion point for patients seeking sacral neuromodulation therapy. Cost-effectiveness studies have demonstrated that rechargeable batteries have similar efficacy as recharge-free devices at a substantial cost saving compared to nonrechargeable devices. For this reason, single-payer systems in Europe have adopted Axonics as their sacral neuromodulation treatment of choice.^3,10

Based on similar efficacies with these devices and a lack of a head-to-head randomized trial, choosing rechargeable versus nonrechargeable neuromodulation treatment options is best made by accounting for patient-related preferences. Lower body mass index patients may benefit from the smaller battery size of the InterStim Micro and Axonics systems. Conversely, patients who desire a more maintenance-free neuromodulation option may choose a recharge-free option. Each device has a different patient and clinician interface, yet the core technology is the same. Ultimately patient selection, counseling, and intraoperative optimal lead placement remain important factors for success and patient satisfaction.

On the horizon are wireless implantable technologies used for tibial nerve stimulation. A small pilot study has demonstrated 75% clinical efficacy with 20 out of 34 participants choosing to continue with a 36-month trial.¹¹

Join us as we take an in-depth look at these technologies and how they can best serve the overactive bladder population during the AUA plenary session, “Nuances in the Selection of Candidates for Sacral Neuromodulation: Which Option Should I Choose?”