Stimwave: Is the Explosion of Stimulator Placement for Chronic Pain Good or Bad?
I write often enough that unless I’m passionate about what goes on the page, it’s hard to keep up. This is one of those blogs that will upset a significant number of my physician readers but because my “Irish is up”, it needs to make it to a blog. The topic is the explosion in the use of implantable stimulators by my colleagues and what patients need to know about this dramatic shift in care. Let’s dig in.
What Is an Implantable Stimulator?
Implantable stimulators are used to help patients with end-stage chronic pain. They involve the placement of an electrode lead that is placed near or adjoining a spinal or peripheral nerve that carries most of the pain signals. Electrical pulses are run through the lead to help block the pain signals through the nerve.
The History of Stimulator Use for Chronic Pain
The medical term for a stimulator used in the spinal canal is “Spinal Cord Stimulation” (SCS). The first one of these was placed near someone’s spinal cord in 1967. By the 1980s, these implantable spinal cord stimulators came into more common use for patients with severe intractable pain. Recently, there has been an explosion in the use of Peripheral Nerve Stimulation (PNS). This means the target nerve isn’t in the spinal canal, but elsewhere in the body. These have been used for everything from chronic headache pain to shoulder to back or leg pain.
How Are these Pain Blocking Stimulators Deployed?
The process usually begins with temporary lead placement. The doctor places a long electrode near the site that they believe will block the pain. If that substantially helps the pain, then the patient is scheduled for permanent lead placement. In the traditional unit that has been used for many decades, the second procedure is performed by a surgeon who places a signal generator (looks like a pacemaker) under the skin and then tunnels the cords from there to the electrode (the part that blocks the nerve). The permanent lead is then placed using x-ray guidance and the surgeon tries his or her best to make sure this stays in place.
The Historic Problems with Spinal Cord Stimulation
There have been all sorts of issues, all of which I have seen happen at one time or another during my career. One problem is that the leads going to the electrode often break. This makes sense, as the patient is constantly moving and yanking on the leads. The generator can also break, as it’s a piece of consumer electronics. In addition, the electrode can move and start zapping the wrong place, leading to no pain relief or even new symptoms. Finally, infections now have a new place to travel which ends up being along the tunnels made for these wires, so infections of the leads and other wire tunnels are not uncommon. Finally, one of the bigger issues is that while the stimulator worked great in the beginning, that same level of relief often doesn’t last, and then they’re left with all sorts of stuff permanently placed in their body that’s doing nothing.
The New Stimulators
One new trend in this world is the advent of small peripheral nerve stimulators that can be energized from the outside, using RF technology. Hence the electrode is placed using a small incision and commonly x-ray and/or ultrasound guidance and then the patient wears an external transmitter over the area. This causes the electrode to emit an electrical pulse to block the pain without an implantable generator. The devices most commonly used are made by a company called “Stimwave”.
Based on the older model spinal cord and peripheral nerve stimulators, complication rates are high. One paper that reviewed all of the literature up to 2014 had those rates as high as 30-40% (1). This was mostly hardware-related issues like the migration of the electrode to someplace it shouldn’t be. The problem is that externally powered stimulators like Stimwave are too new for many publications on their complications. I did find a reference to one study for a similar type of stimulator in a Cigna coverage document that states that the rate was 23%. However, there just isn’t much out there right now. If any reader knows of other studies not paid for by the company or its surrogates, I would love to include those here.
Hence, with the lack of much published in the National Library of Medicine, I went to the FDA device complications reporting system (MAUDE) and found these reports on the Stimwave product (which I shortened for readability):
“I had a stimwave spinal stimulator trial. Wires were implanted into my back on monday, (b)(6) 2020. At 4:20am on (b)(6) i was awoken by a sharp shock…The shock was so severe i was jerking around, my heart was pounding and i couldn’t see. I tried to remove to turn the stim off but couldn’t. After the shock stopped a few seconds later i immediately turned the stim off and removed the control unit. I was shaking, my heart was racing. I was hurting everywhere and very scared. I called the tech and had to leave a message…The dr took pictures of the wires placement in my back. Then removed the wires from my back. The dr did not deaden my back or give me anything for pain relief before removing the wires with great difficulty from my back. The pain was almost unbearable…My leg and back pain is even worse than before and i still have the pain from where the wires were in my back. This spinal stimulator needs to be banned…”
“New / worse symptoms; i have received the stimwave wireless pns on (b)(6) 2020 and after anesthesia and pain med wore off become extremely nauseous and vomiting…Upon waiting until monday’s appt to extract the temp leads, the shocking sensations increased and a burning sensation began that became to intense that had to turn off device. The rep appeared to care about the sale and not the actual fact that we should have stopped it at the first sign of nausea after reprogramming. Apparently the rep had never heard of the nausea / vomiting or the burning sensation of where lead placement was and as someone who works in the cro industry i feel that this is something that should be reported as this is a newer device to the market and all ae’s should be reported as i feel the rep would not do this. Fda safety report id# (b)(4).”
“I have two stimwave stimq devices implanted in my right shoulder/back/neck. They terminate at the greater occipital nerve on either side of my neck. Devices were implanted after 25+ years of chronic migraine pain. The clinical trial went very well – the externally-located unit and battery provided approx 75% relief, so we had the devices permanently implanted. The clinical trial was in (b)(6) 2018; the permanent implantation surgeries were in q1 2019. Since the implantation surgeries, i have had a myriad of problems: one of the implants migrated and had to be removed in emergency surgery. The healing process resulted in multiple repeat visits for sutures and implant parts extruding from my back. The skin healing process (or lack thereof) has left numerous disfiguring scars which are paper-thin. I am still having debris (internal sutures) extruding from the scar tissue at this time. The pain relief i received during the trial has never been matched. At best, relief levels are approx 30%. The batteries that power the external wearable antenna assembly (waa) have failed at an alarming rate. I am currently in possession of batteries #5 and #6; the first four failed completely and have to be rma’d with stimwave. For a timeframe of approx 18 months, the number of device failures is exceedingly high. As for the impact on my life due to the repeated problems with these devices: i have been on short term disability, long-term disability, and ultimately lost one job (so far) due to an inability to work. I have been at my current role for less than one year. I exhausted all of the pto i was given in my initial offer letter/signing package for fy 2019, and i have already exhausted my pto allocation for fy 2020 because of the number of days i have had to miss work due to the incapacitating pain. I have lost most independence in my life, i can only drive at specific times (depending on how i am feeling). I cannot care for my pregnant wife; and i cannot care for my (b)(6) year-old son…I have also received email communications from stimwave which intimated/articulated that they are aware of the quality issues related to their battery units. It is also alluded to that this was the cause behind replacements of stimwave executives earlier this year. I am certainly happy to share any information i have received. Fda safety report id# (b)(4).”
So it looks like the same types of adverse event reports we see for other types of stimulators.
Nonreporting of Problems?
One of the things that concerned me when I went to the FDA MAUDE complication system was that despite an explosion of the use of these devices, there were only two pages of complaints. When I have searched other devices like SI joint fusion implants on the same system, there are pages upon pages of reported complications. Given that the Stimwave system has many more moving parts than a screw, this seemed curious. Then I found this report:
August 23, 2019
FDA investigators found Stimwave Technologies’ complaint handling procedures for its implantable pain treatment devices were not up to par, during a Jan. 29-Feb. 15 inspection of the firm’s Pompano Beach, Fla. Facility.
The company makes wireless pain relief products called the Freedom spinal cord stimulator and the StimQ peripheral nerve stimulator that target nerves causing chronic pain. Faulty devices were returned to the manufacturer for not charging, not connecting or powering on and overheating, but many of the complaints were not entered into the firm’s complaint handling system.
Complaints of software-related performance problems did not go through the firm’s complaint handling procedure, which meant they were not evaluated to determine if the events should be reported to the FDA.”
So is the lack of reported complications due to interference by the company? Meaning that it looks like the sales reps should be the ones telling patients and physicians to report these complications or reporting themselves.
An Explosion in Stimulator Placements
Because old-style stimulator placement involved two physicians and the costs were tens of thousands of dollars (sometimes much more), placing stimulators in patients was always a small niche in the pain management world. Meaning, that 99% of pain management physicians just didn’t offer this because of the hassle and also because it seemed to only apply to a small number of their patients. However, all of that changed dramatically when products like Stimwave came on the market. These small peripheral nerve stimulator systems (like StimQ PNS) could be implanted by one physician using x-ray guidance and could now be deployed to treat lots of pain areas in the body. Add to that attractive insurance reimbursement, and based on what I’ve seen, we have about a quarter to a third of all interventional pain management physicians who now implant these systems. That means that the number of implanted systems has gone from thousands a year, to likely tens of thousands.
When Is This Appropriate?
Listen, any procedure performed in complex chronic pain patients can make them worse. The more complex the patient the more likely that negative result becomes. That risk also goes up when you’re implanting something in the body. So the fact that serious complications have been reported for Stimwave and the very popular StimQ PNS system is not surprising. Again, what is surprising is that IMHO, there could be a massive under-reporting of these problems.
First, it’s important to note that I’m not anti-stimulator. There are patients out there that swear by their implant. They had no other legitimate option. In addition, having more options to treat patients with chronic pain is ALWAYS better than fewer.
Having said all of that, when is this type of device appropriate? After EVERYTHING less invasive has been tried and failed. My concern is that many procedures that could help these patients, like orthobiologics, are commonly skipped over because they have poor insurance reimbursement. So patients that could be easily treated with less invasive options are getting offered the more invasive treatment because of their insurance status and not because it’s the least invasive thing that may get the job done.
This Is Not a Popular Message
I expect that about a quarter to a third of my colleagues will not like this blog. Again, this practice of implanting stimulators has exploded. Hence, if you’re firmly on the Stimwave train, this blog is the last thing you want to see. Having said that, “I call ’em like I see ’em”.
The upshot? At the end of the day, while it’s great to have options like the Stimwave, StimQ and other PNS or even SCS systems, physicians need to balance what’s best for the patient with what’s covered by insurance. Meaning, expanded informed consent needs to be used for these devices so that patients understand that there may be less invasive things that can help, but the choice to implant a stimulator was based on what their insurance company will cover.
(1) Eldabe S, Buchser E, Duarte RV. Complications of Spinal Cord Stimulation and Peripheral Nerve Stimulation Techniques: A Review of the Literature. Pain Med. 2016 Feb;17(2):325-36. doi: 10.1093/pm/pnv025. PMID: 26814260.