So thank you very much for attending. Just out of curiosity, my name is Jennifer Sweet. I'm at Case Western University. Just out of curiosity, how many people here are in spine practice or going into spine practice? Okay. And how many are pain physicians or pain management or functional, stereotactic functional? Okay. And so most of you I'm assuming are just learning to, wanting to integrate this. How many are actively performing spinal cord stimulation techniques? Okay. All right. So this should be an interactive morning. So if you have questions, feel free to interrupt or ask questions throughout the day. And I'm going to be talking about patient selection. So even if you are not actively implanting spinal cord stimulation or any of these devices, I think it's important for all surgeons to be comfortable with what the indications are for these patients. I have no pertinent disclosures. And so if your pain patients who come into your practice look anything like mine, they might have these bags of medications looking like this. And that's exactly what we're trying to avoid, especially in this day and age with this opioid epidemic. So the goal with these neuromodulation technologies is to really reduce the use of these medications. Low back pain is the second most common cause of disability in the U.S. and the most common location of neuropathic pain is in the back and the lower extremities. And data suggests that neuropathic pain is much more likely to be a chronic process, to be less responsive to analgesic medications, and to produce a long-term disability for patients. And this can be also associated with depression, personal stress, financial stress if they lose their jobs. The goal of treatment for these is pain control, reduction of medication, and an improved quality of life. The FDA indications for spinal cord stimulation currently are as follows. It says that spinal cord stimulation should aid in the management of chronic intractable pain of the trunk and or limbs associated with the following conditions. Most of these are actually redundant conditions. We're going to be focusing on these two as these will be probably the most common ones that you'll see in your practice. And so failed back surgery syndrome is the clinical situation in which patients suffer from chronic back and leg pain following an anatomically successful spine surgery. Between 10% to 40% of patients who've undergone lumbosacral surgery in the U.S. still experience this persistent back and leg pain. And these patients, by definition, have failed all other treatment modalities for pain control. And so they still have chronic pain, which is very difficult to treat. It's thought that this might be due to epidural fibrosis that can occur, potentially with tissue manipulation, bleeding during surgery, or inflammation in general. And this might result in epidural fibrosis of the nerve roots, causing entrapment of the nerve roots, decreased perfusion, and over time can result in this really difficult-to-treat neuropathic pain syndrome. So let's look at some of the data to show why you should use this and really when to use this. This is a study by Kumar et al., and this was the first really great study showing that spinal cord stimulation versus conventional medical management can be a better option for patients with chronic pain. This looked at 100 patients with failed back surgery syndrome who had primarily lower extremity pain, and they were randomized to receive conservative medical management plus spinal cord stimulation or conservative medical management alone. This was a multi-center study, and at six months, patients were deemed successful as the primary outcome measure if they had greater than 50% relief of symptoms, and they were permitted to cross over to the alternate arm at six months. So what this study showed was that at six months, 24 spinal cord stimulation patients and four conservative medical management patients achieved the primary outcome. So compared to the medical management group, the spinal cord stimulation group achieved significantly greater relief of leg pain and back pain. At the six-month period, the crossover rate for spinal cord stimulation patients was only five out of the 50, and 32 of the conservative medical management patients crossed over at six months. And the improvement was sustained at 24 months, but you'll see that still that number isn't ideal. So even though this data is significant to show that conventional, and when we say conventional, you'll hear about this later, we mean tonic delivery of tonic continuous stimulation where patients typically feel a paresthesia in their limbs. That's what we mean by conventional spinal cord stimulation, that this is only a 37% improvement over medical management at two years. I should note that a subsequent study with similar methodology was done for this, and it followed patients up to seven years. And in that group, 52% of patients had prolonged relief at seven years. So there are other studies showing that. Treatment of chronic pain, cost effectiveness, this was also looked at. Now, while spinal cord stimulation is initially more expensive than conservative medical management, the data shows that by 2.25 years, you'll have a cost-neutral balance. And over time, this can be extremely effective. So Kumar et al. looked at this at a five-year period looking at quality of life and cost effectiveness, and they found that overall patients had significantly improved quality of life and improved cost efficacy for spinal cord stimulation. And 15% of these patients returned to work at five years as opposed to zero in the medical management group. A subsequent study with Kumar et al. and RISD looked at this over a 20-year period and showed the same results, that over time there's a substantial cost benefit to performing these neuromodulation techniques. Now, how does spinal cord stimulation surgery compare to revision spine surgery? In this study by North et al., they looked at patients with failed back surgery syndrome who were randomized to receive either revision or spinal cord stimulation. And again, at six months, they were able to cross over to the other group. And what they found was that the spinal cord stimulation patients, 47% had improvement of their pain compared to 12 in the revision spine surgery group. Of those who crossed over, 5 of the stimulation group crossed over, and 14 of the revision group crossed over. Of the ones in the spinal cord stimulation who crossed over to revision surgery, none of those patients improved with revision surgery, whereas 43% of those who failed the revision surgery improved once they got the spinal stimulation. And this study also showed that this can be useful for reducing or stabilizing the use of opioids, 87% compared to 57% in the revision rate. And so this slide, I think, is very important as well regarding the timing of spinal cord stimulation because why might these therapies be so effective in some and less effective in others? Well, these studies showed that the sooner you implant these devices, the better patients will do. Kumar looked at 410 patients over 22 years treated with this, and they found that the success of treatment was inversely proportional to the timing of surgery. So spinal cord stimulation that was implanted within two years had greater than 85% success, but those that were implanted more than 15 years out from their pain had less than 9%. And so this begs the question, why are we waiting for this to be a last resort therapy? Minimally invasive technology and the results are quite good if you implant early on, and so that's just something else to consider for your patients, that this doesn't have to be a last resort therapy. And then I'd like to just briefly touch on some of the newer studies in the last few years, and there'll be some other talks discussing this. But what we had talked about before were all of these was basically conventional spinal cord stimulation to medical management and to revision spine surgery, but there are now newer trials demonstrating that novel forms of stimulation can be just as effective, if not more, and there are a number of different kinds of novel forms. This was the SENSA trial looking at the delivery of high-frequency stimulation at 10 kilohertz, and in this study they compared high-frequency stimulation to conventional spinal cord stimulation, and they looked at both back and leg pain, which is also different than a lot of the prior studies. A hundred and seventy-one patients were trialed and implanted, and at three months the patients in the high-frequency stimulation group had significantly more improvement of both back pain and leg pain. It should also be noted that in their inclusion criteria, they included patients who had previous spinal cord surgery and also patients who didn't necessarily have spinal surgery. And all of these patients improved, so there was a non-inferiority as well as a superiority to this newer form of stimulation compared to others, the conventional studies. And this was true at two years out. The SUNBURST trial is another study. This is looking at burst stimulation called de Ritter burst stimulation, and this was another randomized controlled trial, and this looked at patients who were randomized to receive either burst or tonic stimulation. In this study, patients received one of the two arms, and then at 12 weeks they were switched to the other arm. A hundred patients were trialed and implanted, and at 24 weeks burst was found to be non-inferiority to tonic stimulation. If you look at the P less than .001, if you look at a P of less than .05, it showed superiority. At 24 weeks they also found that patients preferred burst compared to tonic stimulation, and at one year this preference was sustained. And so, again, these novel forms might be even better. So if one of the arguments against using spinal cord stimulation that you use or colleagues use is that the results still aren't great, well, now we have newer forms of spinal cord stimulation that show really they are great and can be much better than prior studies. So ultimately spinal cord stimulation is something that should be recommended for patients, and multiple pain societies and surgical societies have concluded this with all the evidence. I'm just going to shift gears and talk about complex regional pain syndrome just because this is an area that we always hear about CRPS, but it can be hard to identify these patients and to really believe the patients at times. So I just want to go into some of the basics of what this is and the diagnostic criteria. This is really a clinical diagnosis, these patients who have CRPS. And so these patients have chronic neuropathic pain, and the Budapest criteria can be helpful in identifying these patients. According to the Budapest criteria, patients must have all of the following. Continued pain that is disproportionate to the inciting event. They must have at least one sign in two or more of these categories. They must have at least one symptom in three or more of these categories. And there can be no other diagnosis to better explain their symptoms. So really patients are just complaining of a lot of pain and some of these other sensory, vasomotor, pseudomotor, and motor symptoms. There are a lot of different names for CRPS, prior names that were used. Currently today we use the terms CRPS-1 and CRPS-2. CRPS-1 was formerly called reflex sympathetic dystrophy, and it refers to the situation where there can be a trauma but no damage or nerve injury is really identified. Whereas CRPS-2, which was formerly causalgia, is when you have a known nerve injury present. What's interesting is with both types, the vast majority of patients will still have a trauma to the limb. They don't necessarily have to have that, but it's very common. Here's something else that I found interesting, and it's just the stages of CRPS progression. Most of these patients will present at stage 1. 70% to 85% of patients with CRPS will have resolution of their symptoms if you start treatment early, and that usually entails within one year of treatment. But 15% to 20% can be refractory, and this is when they can progress through the stages. In stage 1, it's purely, again, a sort of subjective description by patients, sensory limb pain, some vasomotor findings that you might see on exam, pseudomotor findings as well. There are really no other supporting evidence for the disease. Stage 2 is really just a little bit more of the same thing, worsening pain and worsening of these other symptoms. You may or may not have radiographic findings. It's only at stage 3 where you can get severe changes and motor trophic changes such as dystonia, or you might find radiographic changes. And so it's important to note that treatment and intervention is most effective in stage 1 when patients are really going to have mostly the subjective clinical history for you. Like I mentioned, it's a clinical diagnosis. You may have other signs to support it, particularly at later stages, pro-inflammatory markers, autoimmune markers, sympathetic skin response tests or bone scan and other things. But this is a clinical diagnosis. I don't know if any of you have seen patients like this. I've seen a couple who have come to me with findings this severe. But, again, this is going to be much later in the game. But you can see quite dramatic findings on their exam. Here you have dystonia seen in the limb. You also have hyperhidrosis. You have the swelling. You have the warmth. So it meets all the criteria. Sometimes you can see osteopenia on X-rays shown here by the arrow. You can also appreciate that there's an asymmetry, tends to be an asymmetry in the limbs. Here you can see increased uptake on bone scans next to the joints. And, again, you see that asymmetry. The treatment for this is going to be a multidisciplinary treatment with physical therapy, psychological interventions like behavioral and cognitive therapy as well as education, and then ultimately pain relief, which can come in the form of pain medications, but also these surgeries. So in terms of the surgeries for CRPS, spinal cord stimulation has also been shown to be quite effective for this. In this study here, 54 patients with CRPS type 1 were randomized to receive spinal cord stimulation and physical therapy versus physical therapy alone. And at six months in the spinal cord stimulation group, there was a statistically significant decrease in pain, whereas in the physical therapy alone group, the pain actually increased at six months. At two years, the pain remained sustained with a benefit in the spinal cord stimulation patients. And what's interesting is at five years, the results sort of plateaued out. However, in an analysis, when they asked these patients with spinal cord stimulation at five years if they would undergo this again, all of the patients stated that it was worth it and that they would undergo the spinal cord stimulation again just because of that benefit that they got at the beginning. So, again, in that one, conventional stimulation results may have plateaued out over time, but just like in the failed back surgery syndrome group, we do have novel forms of technology that have also shown superiority now to conventional spinal cord stimulation. So this is dorsal root ganglion stimulation, which you may or may not have heard, and it's FDA-approved for complex regional pain syndrome. The accurate study is a nice randomized control trial that demonstrated the benefits of DRG stimulation compared to conventional spinal cord stimulation and again showed that 81% of patients versus 56% obtained greater than 50% relief, and this was superior to the conventional management with conventional stimulation. So, again, these novel technologies are sort of changing the game and making our therapies even better for patients, and the recommendations for CRPS would include spinal stimulation. So, in summary, the primary indications for this would be neuropathic pain syndromes, including failed back surgery syndrome. Spinal cord stimulation is superior to medical management, superior to revision spine surgery. Novel forms of stimulation are superior to conventional stimulation, and for CRPS, we found similar findings. Spinal cord stimulation is superior to conservative management, and novel forms such as DRG can be even superior to that. Do you have any questions for me? Yes? Yeah, for those, you showed, initially you showed a process trial and another one, I forget the acronym, et cetera. And 48% had improved with SCS, I believe, in the process trial. Were those patients who all had a test trial before the permanent unit was implanted? Yes, good question. They all had that. I'm seeing if I have it in my notes. I had it beforehand. But in all of these studies, they essentially had a trial and then went through to implantation. Typically, the rate of conversion would be 10% would fail the trial in most of these studies, and then the majority, 90% or so, would proceed on to the implant.

spinal cord stimulation

chronic pain management

failed back surgery syndrome

high-frequency stimulation

complex regional pain syndrome