Hi, my name is Dr. Madi Schnur and I am here to talk to you today about patient selection for neuromodulation. So why is it important to have good patient selection? One, we know that there is a certain population of patients whom we implant with permanent devices that experience inadequate relief. For spinal cord stimulation, that's about 30 to 40% of patients, which is quite high. With the right patient selection, we know that those numbers of patients who experience long-term relief can go up or down. The other thing is that treatment failure, meaning the patient does not receive as much relief as they expect, this is associated with patient dissatisfaction and inevitably dissatisfaction of the patient with you as a physician. We also know that the expense to remove some of these devices, probably the majority of them, occur to both the patient as well as to society as a whole. Patients need to take time off of work, they have spouses that need to take time off of work, which inevitably can lead to wages that are lost for them, for their family, etc., etc. And in terms of the devices themselves, the cost benefit for many of them, such as spinal cord stimulation, exists really via the longevity of the device. We know that this is also true for intrathecal pumps and probably some of the other devices we place, like peripheral nerve stimulators. Some things to take into account. One, I would encourage you all to really place devices using FDA-approved indication. Additionally, ensure a positive response to a trial if one is required. To my knowledge, for most of these devices, a trial is required, and I consider a positive response 50% or greater, although what I really want to see is 80-90% relief to a trial. The other thing is, before deciding to place a permanent device, ensure that it's safe, meaning can the patient really tolerate surgical intervention and anesthesia? Make sure that the patient is not pregnant. Make sure that the patient understands the risks of the placement and that the patient is able to operate the system once placed, meaning if there is a handheld charger or something that they can perceivably increase power or go to different device settings, patients should be able to do that independently. Just talking about the different devices that we place. So some of the indications for spinal cord stimulation include CRPS, failed back surgery syndrome, diabetic neuropathy, phantom limb pain, low back pain, refractory angina, and end-stage peripheral vascular disease. Some of these off-label uses are widely accepted and approved by insurance. Just something to be aware of that they are off-label use. Indications for DRG, neuropathic pain after surgery. Sometimes this actually is failed back surgery syndrome. And then, of course, CRPS type 1 or 2 of the lower extremities. Sometimes for placement of this, patients will have more focal neuropathic pain. And I've seen this successfully placed for indications like pelvic pain or phantom limb pain, which some of these are in that category of neuropathic pain after surgery. Some indications for intradenal pain pump, cancer pain where you anticipate more than a three-month survival, spasticity, right? So indications where we're going to fill the pump with baclofen. And then, of course, chronic pain that's failed conservative treatment with medications, PT, and potentially other medications. And potentially other procedures or injections. Some things to think about are, does the patient have favorable anatomy for placement of an intrathecal catheter? And then, of course, consider the ability of patients to return for refills. Right now, I have some patients that travel up to three hours to see me in northern Minnesota just to get their pumps filled. And that is quite a distance for most people, especially in winter where I live. And that's because they don't really have any other good options near them. Some of the indications for permanent peripheral nerve placement, chronic non-cancer pain, which is more focal in nature, stump site pain, focal neuropathic pain, and, of course, chronic hemiplegic shoulder pain. None of these lists by any means are the comprehensive list. These are just some of the most common placement for these devices. So in terms of choosing patients, one thing that's important to think about are the psychological risk factors. One, do your patients have really realistic expectations? Do they expect 100% pain relief? We all know that that is probably not likely for any device placement and or really procedure. And so I always make it clear that what I'm really hoping for is 50%. But I really want to know what's important to the patient. And sometimes that's they want to be able to sleep at night or they want to be able to get through their chosen work on a day-to-day basis. I often also talk to patients that most of the devices that I place, I expect them to be permanent and do not ever anticipate really the removal other than changing the battery if needed. Additionally, some of the devices, it can be quite difficult, let's say, for a tined lead, so a lead that has barbs for peripheral nerve stimulator. Sometimes that can be quite difficult and you might need help if they were to be explanted. One absolute contraindication would be ongoing substance abuse. Those patients should be treated for that prior to any placement, as well as any untreated major psychological disorder. That would also be an absolute contraindication. Thinking about patient demographics to consider when choosing patients. One is BMI. And why is that? We know that increased BMI is associated with negative outcomes in placement of spinal cord stimulators. And in fact, several studies have shown that increased BMI is a risk for readmission after implantation. One of the reasons for this is really the risk of infection. But the other thing is, as BMI increases, many of these patients haven't received the relief they expected. And so in that placement of these devices may not be as successful in patients with higher BMI. Along these lines, diabetes is always something to consider. One, because the higher the patient's hemoglobin A1C, potentially there is more concern, one, over healing and two, for infection. And so the NAC guidelines, which I'm going to talk again about later, recommend really optimization of patients' hemoglobin A1C levels. And really, when you should be having this discussion with the patient about their hemoglobin A1C is when you start talking to them about trialing a device. So really before placement. And that's because oftentimes people need to work on decreasing their hemoglobin A1C and getting their glucose under better control for many, many, many months. Additionally, same thing with BMI. One other factor that I always make sure to discuss with all patients that I'm considering implantation for is smoking. One, we know that smoking is associated with accelerated spine degenerative changes, right? So the concern is, even after you implant many of these devices, particularly spinal cord stimulators, are you going to get the relief that patients are expecting? And the other thing is, these patients that smoke have decreased wound healing. And so always a risk for infection again. And in terms of the NAC guidelines, they recommend smoking cessation to reduce infection risk. And in all of the patients that I personally implant permanent devices in, I require smoking cessation. Moving on to patients who use opioids and other medications. Most studies indicate a negative association between opioids and outcome. We've seen this particularly with spinal cord stimulation. What we know is that in some patients who take more minimal levels of opioids, that after implantation of a spinal cord stimulator, they may have a decreased use of opioids. One study showed that in patients who had oral morphine equivalents that were greater than 90, this itself was predicted of explant of the spinal cord stimulation device. In terms of other neuropathic medications, there, of course, has been talk about negative associations with spinal cord stimulation. Meaning a patient on gabapentin or Lyrica could this lead to decreased efficacy of their spinal cord stimulator. But so far, there hasn't been any definitive outcome documented. And then I didn't include it on the slide. However, benzodiazepines have also been associated with negative outcomes, particularly with spinal cord stimulation. Although, you know, there is a question if some of this, the use of benzodiazepines is actually like untreated psychological disorders. So something always to consider. And really, one of the biggest things and the reason why I carefully choose my patients is I'm always, always worried about infection. And so in all of the patients that I'm discussing any type of neuromodulation implant, I discuss if they've ever had any previous surgical site infections. If they had, did they have to see infectious disease? And what in particular was the infectious cause? You know, was it MRSA? And how are they treated? If somebody, let's say I was placing a spinal cord stimulation, spinal cord stimulator in somebody that has had an infection after neurosurgical intervention of their spine, I generally will consult infectious disease regarding perioperative antibiotics. Other things that always give me pause is if somebody is undergoing cancer treatment, and if they are having to undergo chemo, if they're able to stop it, I generally will talk with their oncologist and we'll come up with a plan. And that's because most chemotherapeutic agents will impair healing and pretty greatly. In patients who I'm placing an intrathecal pump and they absolutely can't stop. Sometimes we make the decision to just continue on. Other medications which I discuss with patients are immune modulators, right? So if patients aren't chronic prednisone, or if they're taking medication for rheumatoid arthritis, or psoriatic arthritis, or lupus, those all carry an increased infection risk. And so we always discuss that. If I'm seeing a patient who hasn't necessarily had a surgical site infection, but has several risk factors for, let's say, developing a surgical site infection. Sometimes I will have them see infectious disease for perioperative planning. And really, importantly, I will have them see a patient who has a perioperative infection. And really, importantly, I talk to patients who are taking anticoagulation medications. And depending on what device I'm placing, we talk about the anticoagulation risk for being off of their blood thinner. And in some of these patients, it's heart attack and stroke. And so we really have to have good conversations for, if you feel like it's worth the risk, then we can do it. But in some patients, that risk is too great. And really, having this conversation with the patient, and probably sometimes their primary care provider, that's really important. And just being honest with the patient. The other thing is, I think it's always really important to discuss alternatives to placement of some of these devices, right? None of these devices are going to 100% cure people's pain. And so a catastrophic stroke or heart attack really could be life changing for some of them. So again, important to talk about it. In terms of what I use for guidelines about how long patients should stay off of their blood thinner, I use the Azra app on my phone. And so the last guidelines that I know of came out in 2017. And so you can look them up on your computer, you can download the app for a few dollars. I highly, highly recommend it. One thing to also think about when talking to patients about this, for example, if you are doing a spinal cord stimulator trial, and let's say somebody was on Plavix, they would have to hold that for seven days before the trial, through the trial, and then restart it 24 hours after the trial. So that is quite a long period of time to have to hold it for spinal cord stimulation. And so again, just something to think about with planning, and again, choosing the correct patient. So I talked a lot about some of the guidelines. So the NAC guidelines are the Neurostimulation Appropriate Consensus Committee Guidelines. So here, I just included kind of a snippet of their article for infection prevention and management. They have actually several other guidelines. One is for surgical technique, one is for placement of cervical spinal cord stimulators. Also noted on here is a lovely paper published in 2022 regarding evidence-based consensus guidelines on patient selection and trial stimulation, specifically for spinal cord stimulation for chronic non-cancer patients. I highly recommend it. And then of course, for patients who are going to get an intrathecal pain pump, there is the Polyanalgesic Consensus Conference, or the PAC guidelines, which last came out in 2017, and I still refer to in practice. So I highly recommend when and if you are going to implant devices, just keeping up to date on all of the latest guidelines that are available to you. I wish you all best of luck in your practice. These are my references. Thank you very much for your time.

patient selection

neuromodulation devices

treatment failure rates

FDA-approved indications

device removal

spinal cord stimulation