Experts discuss tibial nerve stimulation, an emerging treatment for OAB.
Scott MacDiarmid, MD, FRCPSC: We both like the tibial nerve. We’ve been treating patients through that nerve for a number of years. The tibial nerve stimulators, the implants, are hopefully here to stay. They’re coming soon. Could you talk about them in general first? Then we’ll be more specific.
Alexandra Rogers, MD: It’s pretty exciting. There are a lot in development. These will be a nice addition to the OAB [overactive bladder] toolbox or menu. There are devices that lie above the fascia in the leg, and devices that go under the fascia in the leg where the tibial nerve lies. There are devices that have a lead either antegrade-placed or retrograde-placed vs devices that are leadless. That’s different from what we’re used to with sacral neuromodulation leads.
The stimulation fields differ. One option, eCoin, has a more forgiving dome-like stimulation from a center cathode to an outer rim anode vs stimulation fields that perhaps are optimized by being flush to the tibial nerve. There are devices that have a primary battery that’s internal, in the body, like our sacral devices, vs devices that have an external power source. There are devices that have automatic therapy with no patient involvement vs devices that have patient management of external devices for therapy. And there are devices that need to be exchanged when the internal primary battery runs out vs those that don’t require any procedural change-out.
Scott MacDiarmid, MD, FRCPSC: I’ll get some phone calls or colleagues ask me, and I agree with you. The big one is above the fascia and below the fascia. You and I have been involved with the Valencia [Technologies] device, eCoin, in its studies, and I like that it has a primary battery. You put it in, leave it alone, and it stimulates the nerve. I had to be educated on the fact that the electrode is facing down, and it can be a little more forgiving. It has a nice wide field that projects toward the nerve, so you’re above the fascia. The nerve is right underneath the fascia, and it stimulates the nerve nicely within approximately 6 mm or less.
The leads, which are going to be just like an InterStim lead in a sense, are similar. They’ll be placed next to the nerve. They have to be pretty close. They stimulate 360 degrees in terms of the pulse. The eCoin device is unidirectional, so you can turn it up pretty well to stimulate that nerve almost like a laser beam, and it’s not going to hurt the skin around it because it’s only going 1 direction deep and not stimulating the skin that’s more superficial, or the subcutaneous tissue. It’s about the size of a nickel and pretty easy to put in. We’ll talk about that a little later.
Alexandra Rogers, MD: I can comment a little on the research I’ve done for BlueWind [Medical]. Full disclosure, I wasn’t part of their trials, but I’m always excited to see all of these data coming out. It’s battery-free, so there’s no battery in the body. It’s an electrical power receiver implant that has 2 bipolar electrodes. There’s an external control unit anklet that’s managed by the patient. It seems like the variation of it has changed slightly, where for the feasibility [study], it was placed above the fascia and sutured in the vicinity of where that neurovascular bundle would be. Stimulation occurred for 30 minutes anywhere from 3 to 6 times a week, where the patient would tailor their treatment. And now with the pivotal [trial] per an ICS [International Continence Society] presentation, the fascia is incised and the nerve is directly viewed, and then the 4 wings next to the bipolar electrodes are sutured into that incised fascia. It seems to be a roughly 5-cm skin excision and the foreign body is underneath.
They have completed enrollment. Hopefully, we’ll be getting that data to the FDA this summer, that’s what they published in Urology Times®. That’s exciting to have many people involved.
Scott MacDiarmid, MD, FRCPSC: You’ve already mentioned the device, but what are some of the data and what’s going on with the BlueWind device?
Alexandra Rogers, MD: I’ve been following the data. They initially had a feasibility trial where the 6-month results were encouraging in 36 implanted subjects. They had a 71% responder rate for all OAB syndrome symptoms of urgency, urge incontinence, and frequency. And they had a roughly 52% responder rate for urge urinary incontinence at 6 months. Forty-seven percent of the subjects experienced adverse events. There was preoperative nerve conduction testing performed as a screen prior to implant looking at nerve integrity.
The implant took 35 minutes. It was performed under local or general anesthesia at the discretion of the implanter. Interoperative testing was done at the physician’s discretion. And then the stimulation paradigm was 3 to 6 times per week for 30 minutes using an exterior power anklet. They followed these data for 3 years looking at 20 subjects, where the OAB syndrome complex, the responder rate was 75%, and the responder rate for urge urinary incontinence was 58% at 3 years per protocol.
They just finished enrollment for their OASIS study that’s being performed both in the United States and abroad. Their primary end point is urge urinary incontinence after 6 months of therapy. The estimated completion is roughly this summer, with the FDA then reviewing those data. There was also an abstract for the ICS [annual meeting] 2021 that I really enjoyed viewing where they talked about the implant procedure on these patients with wet OAB. The 3-cm implant is secured to the tibial nerve bundle where the fascia is incised and then these wings to these 2 bipolar electrodes are sutured down. That’s a little different from the feasibility trial, where it was sutured above the fascia. Interrogation was performed, and it was roughly a 20- to 30-minute procedure. They did daily sessions for 30 to 60 minutes. It was powered by a wearable cuff managed by the patient.
That’s my summary of the data that are out there, but it would be great to bring people who have been part of that study into the next Urology Times® chat to see how we compare with those.
Transcript edited for clarity.