#73 - Therapeutic Laser for Treating Pain, Part 1

Hi guys, welcome to another episode of The Factor Podcast. I'm your host, Jessica Riddle. If this is your first time tuning in, welcome and thank you for listening. The topic that we're covering today and in our next episode is therapeutic laser and its applications for treating pain. Now, therapeutic laser and other light therapy devices have surged in popularity in recent years, so much so that you'll be hard-pressed to attend any healthcare conference without seeing these types of devices there. In this 2-part training, we will hear from Mark Callanan, a Doctor of Physical Therapy and the Director of Clinical Education and Recovery Sciences for Inovis, the company behind brands such as Chattanooga and LightForce Lasers. We will talk about laser therapy's role in treating acute and chronic conditions and the more nuanced applications for radiculopathy. Dr. Callanan will also talk about treatment protocols that follow a patient's nerve pathways and how the heat generated from high-level laser can address muscle spasms and joint stiffness. This particular training, which was originally offered, of course, in webinar form, featured a ton of great visuals, graphics, and references to relevant research. So you'll want to be sure to click in the webinar replay link in our show notes if you're more of a visual learner. Let's cue the intro music and get started.

Excited to be here, and today's talk is really designed to just be an overview of what laser therapy is. There's a lot of sort of smoke and mud out there in the, in this space. A lot of misinformation, and I spend a lot of time trying to get good information out to everybody. So hopefully when we wrap things up today, you'll have a little better feeling on how lasers really work from a mechanistic standpoint, some of the recommendations from different groups and research that's supporting the use of lasers, so that for those of you that are trying to really follow an evidence-based path, feel comfortable that laser definitely fits into that category. So I'm a physical therapist by training and received my doctorate in physical therapy from Marymount University in Arlington, Virginia. I was in the outpatient space for over 18 years before joining LightForce back in 2017. I was the director of clinical education. A couple years ago, LightForce was acquired by now Inovis. It was DJO Global. And since that point, I've been the director of education and marketing. For Enovus. So that's kind of what I've been up to. And again, happy to be here today. So what we're gonna go over today is a general overview of the definition mechanisms of photobiomodulation, which is the term for laser therapy now that's accepted in the research. Take a look at some current research as well as different support guidelines that are out there from the APTA, the American College of Physicians, the American— it should be Academy of Orthopedic Surgeons. A little bit of a typo there. And when we're done, hopefully the takeaways will be that you'll understand how laser really impacts cells, understand how wavelength, power, and dosing will impact outcomes, be able to explain the differences between high and low-power lasers with regard to how they impact pain, because there is some differences there that are pretty significant, and explain how to effectively incorporate laser with other treatment concepts in an evidence-based manner. So when you hear laser, I'm not sure what comes into mind, but it might be something like this. For your patients, when you mention laser, they very well might be thinking about this. So it's really important to help provide good instruction as to what it is and how it's going to help them, and that it's a safe modality. Because when you mention laser, sometimes fear can become an issue for those folks. So from a historical standpoint, back in 1903, the only Nobel Prize that was ever awarded to a modality that I'm aware of was awarded to Niels Finsen, and it was used to treat these large sort of purplish blotches called lupus vulgaris. And they found that if you use light boxes with specific wavelengths, that they were able to help clear that up. So that was a pretty big date over 100 years ago now. And sort of the beginning or the advent of laser as we know it started, most people would agree, in 1967, where Andre Mester was a physicist and he was looking at mice. And trying to figure out if you put laser light on their skin, if it created cancerous tumors. And it didn't do that, but it caused some hair growth to, to show up on their backs. And that sort of sparked the question of, well, what's going on there? And since then, research has been going on to figure out what happens when you put these special wavelengths of light onto tissue. So from a chronological standpoint, these are just some significant dates as far as laser goes. If you've noticed, if you've done any research on literature or on laser, you would notice that there's a lot more low-power studies that are in PubMed or CINAHL. And the primary reason for that in the United States is just that there's been a 30-year head start on FDA clearance for the lower-power devices. In 2004 is when the FDA cleared use of Class IV devices for human use for therapy. So since that time, the amount of research that's been out has increased significantly. And there's been a number of significant endorsements from different groups for laser therapy. The World Health Organization, APTA, has made several different endorsements for different clinical pathways, which we'll talk about more in depth here later in the talk, as well as some things from the American College of Physicians, the American Academy of Orthopedic Surgeons, as well as a recent position paper from the CDC. So definitely getting a lot of acceptance on this modality, which is exciting. If you do look for research on this, you want to look underneath the term photobiomodulation. This is the accepted term for laser, and the most current research will be underneath this. So if you're doing a MeSH head— MeSH header search, you'd want to use photobiomodulation plus whatever your topic you're looking for— low back pain or neuropathy or whatever it might be— and you'll get the most current stuff. The other MeSH header where most of the older research falls under is LLLT, which stands for low-level either laser therapy or low-level light therapy. It wasn't quite specific, but that LLLT moniker was used for many, many years as the primary MeSH header. So looking under those 2 headers will help you find out what's going on. I often hear there's no research on laser, and it's because people put in laser and low back pain, and it's not specific enough. So just a heads up on that. So when you think about photobiomodulation, think about is you're trying to impact cell metabolism. So, I put this picture of jumper cables on a battery when your car's dead. The light kind of does the same thing. It excites mitochondria and sort of wakes the cells up. So, as light's absorbed, it impacts ATP production, it impacts nuclear function from an mRNA/RNA function, which is important for cell replication, as well as a number of things that happen at the membrane level. So, think of it as instead of a sick cell going towards apoptosis or dying, the laser helps pretty much rejuvenate it. It's like putting sort of life paddles on that cell and helps try to prevent it from, from having to pass away and get basically gobbled up by macrophages and replaced. So when you put light into the tissue, you're trying to impact the mitochondria, and that is happening more specifically on the inner mitochondrial membrane where you have the electron transport chain. So I have a little diagram here to help kind of walk through that. But basically what this is showing is the electron transport chain, and as the Krebs cycle pumps away, what happens is that it produces ATP. When you have a damaged cell or a cell that's in a low oxygen state and it's, it's not in a healthy state, what will happen is that nitric oxide will bound down here on this 4th ribosome on the electron transport chain, cytochrome c oxidase. And the thought is that when light hits that, it— with very specific wavelengths, there's chromophores there that can absorb the light, and it releases that nitric oxide, and it frees up that block on the electron transport chain and allows normal oxidative phosphorylation to take place. So it's a pretty cool little cartoon, but this format doesn't work with that, unfortunately. But that's what that was about. So from a review standpoint, you basically are putting light into the tissue. It's going to increase the activity of cytochrome c oxidase. It's going to increase the mitochondrial function, which will increase oxygen consumption, better ATP production, which will help restore the energy balance in the cell to help it from basically going into apoptosis. So if a patient were to ask you, how's it work? If you know these little talking points here, you'll be in pretty good shape. So what is laser indicated for? Most companies use a similar indication. This is for our— for LightForce. It's our 510 clearance with the FDA. And basically it states that the laser is able to be used to elevate tissue temperature for temporary relief of minor pain, joint pain and stiffness, minor arthritis pain or muscle spasm, and temporarily increase localized blood flow and increase relaxation of muscle. So this is essentially the first submission for laser in the US, and most companies have basically just used this as, as a predicate to allow them to go to market underneath these same parameters. Know that this was submitted many, many years ago, and it doesn't really bring into the account of all the different mechanisms of photobiomodulation. So don't be fooled if you look at the indication statement on a laser and feel that maybe it's not doing some of the things that you've read that it can do. That's not really the intent of this, the, the FDA clearance. It's just what has been filed for usage for that, the that device, and it does impact what can be said on label about the device as far as marketing and things of that nature. So that's another 10-minute discussion we could get into, but just understand if there's a mismatch of your understanding, that's probably why. So more realistically in the clinic, what can the laser do? It can treat a whole bunch of different things with regard to both acute and chronic pains. It can help provide pain control that is non-pharmacologic and non-invasive. Hopefully be able to possibly delay some orthopedic procedures. There's been many case studies that have been done looking at folks with, say, knee OA. They get treated with laser, with therapies, and it helps prolong the time needed to get total knee arthroplasty. So it can be used as a management tool as well. Contraindications for laser, generally they're pretty consistent for most of the companies. This is from our LightForce units. Basically, you wouldn't wanna apply laser over a pregnant abdomen or low back or SI area. You wouldn't wanna do it over growth plates for children. Definitely wanna try to avoid over electronical components like pacemakers or pain pumps, things of that nature. Not that there's a huge risk, but the thought is that if you got too much light on a dark lead wire, it could possibly heat up and cause it to short out, which would be a bad day for everybody. So we just advise people to stay away from any type of electrical implant on the patient. You can treat distal to it or proximal to it, but just not over it.

How would you like to get even more great content from Factor in your inbox each week? Things like early access to exclusive free trainings, coupons and promotional offers from our online store, and timely updates on research and news you can use to grow your practice and improve your patient care. If I've piqued your interest, you should be sure to click on the Factor 5 Things Friday link in our show notes. Simply give us your contact details and start getting our weekly Factor 5 Things Friday email in your inbox. It's a simple bullet point style format with no fluff, just tons of great content and resources you can use for continual professional growth. So be sure to visit the show notes, click that link, and keep an eye on your inbox each Friday. Now back to the show.

And then you wouldn't want to try to treat over glandular tissue. So it's mostly this comes into play in the neck with the thyroid. You wouldn't want to do that because it could overstimulate it. And impact metabolism essentially over the testes or ovaries. They're, they're pretty deep, so that's really not a huge concern there, but you wouldn't want to target that with the treatment. And then lastly, people that are taking photosensitive meds— corticosteroids is the primary group that are impacting physical medicine— that can make them photosensitive and more likely to have a thermal injury on the skin. So you want to be very cautious with that. We generally recommend waiting at least a week after somebody's got a corticosteroid injection before doing laser treatment on them. But if they're on some sort of oral prednisone or something like that, you'd want to ask that patient some questions about how photosensitive they are with that medicine and then discuss that with the patient. So we're going to get into wavelength and how that impacts photobiomodulation. And this is just a quick diagram of the electromagnetic spectrum. So it goes from gamma rays, which are where— over there on the left, and then can go all the way over towards radio waves. The wavelengths that PBM utilize are in the near-infrared infrared range. So that's just north of the visible light spectrum. So you'll see on most of the wavelengths for these devices, it's going to be somewhere between 635 nanometers and up to maybe just a little bit over 1,000 nanometers. And we'll get into a little bit on why they might choose different ones, but just so you kind of get a sense of where those wavelengths are in the spectrum, I put this on here. Generally, the frequencies go down as you go over towards the right. So essentially, think about like gamma rays and X-rays. They're very high energy, and that high energy, high frequency, they're ones that can create problems with cells, so they can create cancers. That's why you wouldn't want to sit with underneath an X-ray for a long, long time, or underneath gamma rays, they can be carcinogenic. The wavelengths that are used for photobiomodulation, they do not cause— they don't have enough energy to cause changes in the cell that way. So they're not, they're not at risk of causing cancer, which makes it a very safe device to be able to use. So if all this talk about light and impacting cells seems a little funny, just to kind of bring it home a little bit, You probably are more aware of photobiomodulation than you think. If you just think about sunlight that's hitting plants being absorbed by chlorophyll, and it's helping produce oxygen from CO2, that is a classic example of photobiomodulation. The thing to appreciate is that chlorophyll is sensitive to 2 real peaks of light, so in the blue range as well as in the red range. And so, if you took those 2 wavelengths away from the light that comes from the sun, we'd probably run out of oxygen because they would not be able to produce nearly as much oxygen as they do. So when you see someone growing possibly a plant in a basement that maybe you've visited, and you notice that they have a blue light sitting over those plants, this is the reason, because the chlorophyll absorbs that blue light readily. So the good news is that these receptors that are in your cells, the cytochrome c oxidase, what this is trying to show is that there is a very large band of wavelengths that they can react to. So, over on the left side, they're most reactive in that 600 range, 650 range. But then, as you go down, they have the ability to react to a lot of different wavelengths. So, when people see this or if they just take a cursory glance at the research, they would say, hey, why aren't all the wavelengths for these devices in that red range, 650? And there are a lot of devices that are out there right now in this red light wavelength, and they're getting a lot of publicity. So, What I would tell you is that if you were trying to treat just cells in a Petri dish, that red light would be great. Or if you're trying to treat things on your skin, the red light is great. But the problem is, is that red light is so readily absorbed by melanin in your skin is that if that was your primary wavelength, almost none of it is going to get below the skin. So it's almost too much of a good thing. So those devices that are primarily just a red light that you're thinking, okay, I can create some photobiomodulation, I would just warn you, if your intent is to treat or things that are on the skin, probably a pretty good choice. But if you're trying to treat things that are below the surface of the skin, tendons, joint capsules, possibly trying to get into a joint or deeper tissue, that wavelength will not really penetrate very well. And I'll show you a couple slides to help clarify that in a minute. So this slide gives you a sense of absorption on the y-axis, and then you have wavelengths on the x-axis, and they're getting longer as you move towards the right. And what it just shows you is that you have different molecules that absorb light at different wavelengths with different preference. So the important line to see on that is melanin, which happens to grab a lot of light in that 600 range we were just talking about. But then you can see that melanin starts to get less absorptive, absorptive as you move towards the 800 to mid-900 range. Once you go past 1 micron, which is 1,000 nanometers, basically. You can see that that dark line on the right, that's water. It starts to absorb light preferentially. So if you have wavelengths that get too long, like out in that range, they're going to basically be absorbed by water, which isn't necessarily what you want to have happen. And if you have wavelengths that are too short on the red side, they're going to mostly get absorbed by melanin, which probably isn't what you want to get done as well. So in the middle of this optical window, they refer to it as, that's sort of the sweet spot on trying to get light where you want it to go if you're trying to get below the surface of the skin. There is no perfect wavelength because, as you can see, you're trading off for various things. Because when you really look at the science, you realize that the intensity of the light as well as the wavelength all will have an impact on how it gets absorbed. You could have the perfect wavelength but not have enough of it, and it won't create a change. Or you could get plenty of light down to a substance, but if it's not the right wavelength, it won't, it won't get absorbed and get impacted. So Understand that there's a lot of research that goes in to figure out the right combinations of power and wavelength so that the devices are effective. So this diagram just gives you a quick sense of how wavelength impacts depth. It's not drawn to scale, but it gives you a sense of as when you're in this optical window, as the wavelengths get longer, generally they can penetrate deeper. So the, for example, the wavelengths that are used for LightForce equipment are 810 and 980 nanometers. They use 2 different diodes to create those 2 wavelengths. And the reason why is they do a good job of getting past the skin, and they've been shown to get absorbed very nicely by different tissues like muscles and nerves and things of that nature, which is why they work so well in this space. But you'll see a lot of companies use a lot of different exotic wavelengths that aren't those same 2. Those are the 2 pretty much most referenced and most researched wavelengths. There's some other ones that show up. Just understand, you need to understand how they're absorbed and how well they penetrate when you're trying to think about which ones you want to apply or what device you want to purchase to treat your patients, because it's important. So that last diagram was wavelength. This one is power. And it just goes to show you that if you have a fixed wavelength, but you have more power, so in this example, it's 5 watts versus 10 watts, you can see that it's going to basically be able to go to the same depth because wavelength will determine the ultimate depth that something can go, but you'll just get twice as much light at that depth. So power is important on delivery, like how many photons can I deliver to a tissue per second at a given wavelength. And that's where when you start hearing, oh, I have higher power, makes it easier to treat deeper tissues, this is kind of the thought behind it. And we'll talk a little bit more about that in just a second. So you've probably seen devices that are LEDs that are on the market. Most of those are like take-home type devices versus the laser devices, but they both fall under this photobiomodulation umbrella, which is true. So you need to know the differences between the two if you're thinking about going down one direction or another. There's some facts you want to know. So basically, when you have a white light or an LED, they are considered incoherent light, meaning that they are like the picture on the left, like people walking around in a mall, and they're just sort of unorganized. Coherent light is unique to laser in that all the photons are moving in sequence together. So that's one of the hallmarks of laser, and that's what makes it very effective at trying to get through tissue and get to depth. So when you look at a laser, it has a couple properties that are unique to it. A, it's monochromatic, meaning it's one wavelength. So it's a very specific wavelength. The lens on a laser can be divergent like they are in therapy lasers. So it starts out and then it kind of fans out. But I'm sure you've all seen laser pointers or the sights on a rifle, a laser rifle. They have a divergent angle of 0 because they want that light that can go and point hundreds of yards away and help target something. I mean, they can even make lasers that can basically— telecommunication ones that can interact with satellites. So if you have enough power, you can basically push light for many, many, many miles. And then the last piece is that they are coherent, meaning that they're in sequence with each other and they're collimated. So they're going to go very straight, basically. So when you hear about classes of laser in the United States, the FDA is the people that assign that. There's some other classes that are on the international side of the world. But generally, when you're talking about therapy lasers, they're going to fall into either a Class 2A, which would be less than 5 milliwatts, Which is essentially the power of a laser pointer. You would have a Class 3B, which would be anywhere from 6 milliwatts up to 499 milliwatts. And then anything over a half of watt, so 500 milliwatts or more, is considered Class 4. There is no Class 5. So Class 4 is a large group of devices. It could be an industrial laser, it could be these photobiomodulation devices.

Okay.

So surgical lasers are often Class 4 devices 'cause they're trying to cut, cauterize, and things of that nature. And some people get misinformed to say, oh, if you have a Class 4 device, it's gonna be dangerous. Those are only for doing surgery. And it's not true. The surgical lasers have very specific wavelengths to attract water 'cause they want it to cauterize. So they use longer wavelengths generally, and they have a very high intensity. So they, they, they make the, the spot very hot, and that's why they work so well to cut and cauterize tissue. But obviously the intensities of the light for the therapy lasers in Class 4 are set up quite differently. So if anybody tells you that, take that wisdom with a grain of salt. Generally, if you put them side by side, the LEDs, the nice thing about them is that they can treat superficial conditions well. They don't have a specific wavelength, but they can put them in a pretty small band of wavelengths. So it's not like a laser that is a single wavelength. But it'll be in a range. Like, for the average car that's made now, the red taillights are LEDs, and so those ranges are usually between 635 and 660 nanometers. The nice thing about those devices is they're cheap, they're light, and basically they can be used to treat superficial things. Because of the low intensity of those lights, they generally don't treat deeper conditions very well. So if you were trying to buy a device to help with, say, wound healing or something along those lines, and it was an LED, and it would say in the, in the red range, it probably would work pretty well based on the research that's out there. If you try to take that same device and treat things that are a couple centimeters below the surface of the skin, probably wouldn't work so well. So when you look over there on the right for laser, they're much better at treating at depth because they can basically have much higher intensities. So you can dial in the wavelength that you want. So you know that, hey, I want something in the 800 range or 900 range, you can basically nail that number. And then you can basically put a lot more intensity or power behind that, which is real important when you're trying to make cells change at depth. So that's where the Class 4 devices, or even the Class 3B lasers, if they're used properly, can reach deeper tissues than the LEDs can. So let's talk a little bit about the impact on pain and tissue repair. This is really a very interesting topic when it comes to light. And understand that when you talk about photobiomodulation as a family, they can generally create the second and third part of this slide, the short-term changes as well as the lasting effects. And why that is, is that if you get enough light to the mitochondria, you can have this impact on the inflammatory cascades. You can have an impact on circulation via nitric oxide being released. So it's not uncommon that you treat a patient, if you dose it properly, they'll come back in a day or two and say, hey, you know what, I think I'm feeling better. And that's because of these mechanisms that are listed here for that short-term and lasting effects. That first one, the within minutes part, that generally has to be done with higher intensity light. So the higher power Class 4 lasers, this is sort of where they shine, pun intended, for being able to change pain with your patients very quickly. So what they call irradiance, or power density, at higher levels, they can impact afferent nerves. And that's what I want to talk about here with this slide. So Vanessa Holanda did this study, 2017 or so, and it was an animal study. But what was cool is she put light down by dorsal root ganglia of these nerves in animals. She also did some Petri dish work. And what she showed was these pictures here on the right. Where when you put intense light on an afferent nerve, you can create varicosities, which is that web-like look you're seeing there. So it starts there on the upper left, which is sort of the control slide, and as you move to the upper right and then down to the middle and down to the lower, basically they were— the nerve was getting exposed for longer periods of time, so they're getting more light to it. And you can see that you created more of those sort of spiderweb-looking, which are basically these sort of outbranchings that happen where the microtubules meet. Things is, A, if you were to take lidocaine— so that's happening from a chemical standpoint, this is happening from a photochemical standpoint— but it's interesting that the nerve responds very similarly to that sort of input, and they both have a similar— in that it changes the pain capability of that nerve. And it does it by the amount of ATP that's distributed amongst the nerve, slows down the conduction velocity. And by doing so, it's a mechanism that's happening, but it's something that's happening when you— So, what I was just trying to conclude there is that when you hit afferent nerves with high-intensity light, you basically can create this change in the afferent, the C fiber, for chronic pain, and the A-delta fibers for more acute pain. And when that happens, you will actually change the performance of that nerve. which will have an impact on pain perception. So this phenomena has to be done with higher power though, in order to make it happen, which is pretty cool. So with regard to tissue repair, these are just some different mechanisms that take place as far as ways that laser can help with tendons or muscles get better. So as far as increasing collagen laydown by better fibroblastic activity, better blood flow to it via new Epithelialization, as well as better blood flow in the short term from nitric oxide release. All those things will get more oxygenated blood to the scene. And then from macrophage activity, it increases their, their ability to chew up tissue that needs to be replaced and repaired, which all are obviously a big help when you're trying to replace damaged tissue. So an example of that was this rabbit study that was done when they surgically basically cut the Achilles and then sewed it back together, and then they treated those tendons with, with laser. And so dosage was pretty small 'cause it was done essentially in vitro. So the amount of dose that was needed is very small. But you can see on the left side, the collagen alignment looks very different than that slide on the right where they did not use the laser. And what's cool is they took magnified version of this and you can really see that there's a very different look to that collagen on the left versus the right. So if you were dealing with a lot of tendon repairs and you were thinking about investing in a laser to try to help with your outcomes, You can sort of get a sense of why it might be a good idea to do that. So to make all this stuff happen, laser, it's important to have dosing on point. And basically when you put light into tissue, one of 4 things is gonna happen. It's either gonna scatter, which means it's just gonna spread out, and that happens on your skin quite a bit. It's gonna be reflected, which means it bounces off. It's gonna be transmitted, which goes— means it would go all the way through. Like when you take an X-ray of somebody, you're transmitting those X-rays through the tissue. The film, and then the last would be absorbed. And that's what you want with photobiomodulation. You want it to get into the tissue, but you also want it to get absorbed. So that's an important concept to remember when you're looking at different papers or things. How well does it get into tissue, but ultimately, how well does that wavelength get absorbed? So when you talk about dose with laser, you're really talking about joules per centimeter squared, which is the amount of energy you put in per unit area. And that is gonna also factor into how many times somebody's treated in a week or how often they're treated in a plan of care. So when you start talking about dose specifically in a study and you're looking at it, it should mention these 4 things: the wavelength that was used, the area that was treated, the total energy that was applied, so the administration time and the power that was used, which should also tell you the size of the spot, which will give you a sense of what they call irradiance or power density. And then how many times they were treated per week. You put all that information together, you have a pretty good feel for the dosing and be able to replicate that study. If they don't put all that information in, then you're probably going to have a tough time replicating what you see. And unfortunately, a lot of papers do not have all that information, unfortunately.

That's it for today's episode. Be sure to tune in for part 2, where Dr. Callanan will talk more about specific treatment guidelines and protocols for tissue depth in order to achieve clinical goals. We will also get a sneak peek into the future of light therapy and new innovations Inovis has in the works. You won't want to miss it. Episode 74 drops in 2 weeks. If you found today's information valuable, do me a favor. And give us a like or leave a review on your podcast platform. Share this episode with a friend. Every little bit helps. We'll see you next time. Hey guys, if you like what you heard today, I encourage you to visit our website at factor-store.com. That's spelled F-A-K-T-R-store.com to find out more information about all that we have to offer. We have a variety of online offerings as well as our hands-on Factor Rehab System course scheduled in cities around the globe. Be sure to also check out our event calendar and bookmark any of these upcoming live webinar dates coming up in the near future so you can join us live. And of course, the biggest compliment we can receive is for you to help us spread the word to your friends, colleagues, and classmates. You'll find all the important links as well as info about our sponsors in the show notes, so be sure to check those out.