Sub-Concussive Forces & Upper Cervical Injury (Part 1): Real-Time Sideline Assessment with Dr. Kevin Jackson

Concussions dominate the conversation in sports—but what about the impacts that don’t trigger a concussion diagnosis?

In Part 1 of this two-part ICA Sports & Fitness Science Council podcast series, Dr. Brant Hulsebus sits down with fellow board member Dr. Kevin Jackson to explore the often-overlooked issue of sub-concussive forces and their effect on the upper cervical spine.

This episode focuses on what happens before a concussion is diagnosed—and why athletes can appear “fine” while still experiencing measurable neurological dysfunction.

Dr. Jackson shares his research-driven approach to identifying sub-concussive injury in real time, including how chiropractors can perform objective, sideline-based assessments using practical tools that are repeatable, defensible, and field-ready.

In this episode, you’ll learn:
• What sub-concussive forces are and why they matter  
• Why standard concussion protocols often miss upper cervical injury  
• How repetitive, lower-level impacts accumulate over time  
• The role of the cranial-cervical junction in neurological function  
• How to perform quick, objective sideline assessments  
• Why measurable data changes communication with coaches and parents  

This conversation is science-based, conservative, and practical—designed for chiropractors working with contact and collision sports who want to operate responsibly on the sideline.

🎧 Part 2 will cover safe upper cervical intervention, sideline decision-making, and when athletes must be removed from play.

Presented by the International Chiropractic Association (ICA) and the ICA Sports & Fitness Science Council.

Transcript

0:05

hello everybody and welcome to another ICA Sports and Fitness Science Podcast, part of the ICA Chiro Cast. I'm Brant Hulsebus chiropractor here in Rockville, Illinois, board member of the ICA Sports and Fitness Science Council, and I'm joined today by a fellow board member, Dr. Kevin Jackson. You wanna say hello? Hello there, and I'm happy to be on the, , on the podcast today, and I thank you, Brant. I know you're in Pennsylvania. In Pennsylvania. Are you? Pennsylvania, which is, , east,, or it's west of Philadelphia and north of Baltimore. To give you a reference. with, , you a pretty nice established practice, correct? Yep. I've been in practice. We've been in practice, as you know, with, I'm in practice with my wife, Selena Sigafoose. Jackson and former ICA president. She is, , we've been in practice for 34 years. Nothing compared to the Hulsebus., How can I describe it as just a three generations of Hulsebus. That's right. Three generations. All at all at same location. No. My, my grandfather wanted to build a bigger practice in Byron, Illinois, and the city council told him chiropractics of fad, it'll never last, and we don't want to empty buildings. So he gave him the middle finger and moved to this location. So, although the Byron Clinics did open until two weeks ago, two weeks ago, they closed it. So, Really? How interesting. so What a, right. So. what a legacy, eh. Yeah. Yeah. today we're here to talk about sports and you know, I take care of a hockey team and we had get together every year, all the sports chiropractors for the hockey teams. And there's one topic this year that dominated our entire convention, our conference, and that was head injuries, especially when it comes to concussions and sub-concussive injuries and stuff like that. And I, I believe that's an area that you also have dived into, did a deeper dive into Correct. Absolutely, absolutely. There's, , lots of misinformation out there and there's lots of, , not concentrating so much on sub-concussive impacts, but as you know, more concussive impacts and that seems to, , be the, , subject of, of concern. But, , to be completely honest, it's, I think it's, you know, sub-concussive impacts happen all the time, every time and create neurological dysfunction. And only chiropractors actually, I think look at this, phenomenon and are equipped to deal with this phenomenon. And, , I'm glad that you're having the podcast because I, I hope that we can get this message out there out to all our chiropractic friends. And, , and practitioners, but, , very, very, very, very important stuff. You wanna give us a little,, definition of sub-concussive so in case people don't know. Yeah, well, let's just take a concussion or a concussive impact. And of course, I think anybody who watches sports would know what a concussive impact looks like. Someone gets a great big hit, , you know, there's some type of injury that occurs, they're walked off the field, they go into a protocol tent., You know, there's some type of deficit, which is, it's a, it's a brain injury. And a mild traumatic brain injury. And it's serious., And it occurs. It occurs frequently.. But something that occurs even more frequent is a sub-concussive impact is every time that your head either take an impact to the head or body to body impact. Anytime that there's torquing and twisting involved with the, , upper cervical area, the cranial cervical junction, you're gonna compromise the vascular system that goes from the spine into the brain. Neurological system, you're gonna impact the, , hydrodynamics,, of the whole system. So there's, there's three systems at work that can be compromised. And, and the deal is this, is that you don't have to have a concussive injury to have a sub-concussive, , dysfunction. So in other words, there's a, there's a distinct difference between the two, as I was trying to allude to, , initially, is that we are really good at looking for. Concussive situations. Now there's all kinds of protocols, but we're really, really, really poor at identifying what is a sub-concussive impact and what is the neurological dysfunction that happens because of it. And it's primarily because no one really specializes in that, area of physiology. Except chiropractors do, and that's why we're on this podcast is, is our mission at the ICA is to turn more chiropractors into sports chiropractors, especially for this one situation. So,, To go further on that, what it actually is, it's, it's known as a subluxation. So what happens is when you take an impact. And your head accelerates, and your neck, neck accelerates well, your brain accelerates and your brain stem accelerates and the blood vessels. And so that, that acceleration of the head creates a shearing force, , that misaligns the upper cervical area. And as you know, it starts to co compromise the, , sensory motor system, the autonomic system. It, it degrades the performance of the individual, , from an athletic standpoint, even an academic standpoint, even an emotional standpoint. And, yet. It doesn't show up on concussive or concussion testing, and yet it will show up on our chiropractic analysis. A lot of people have these, I know I have a lot of new patients that will come into my clinic and they'll tell me, I'll show 'em an x-ray and they'll have a horrible surgical curve. Yeah. have a lower cervical spinous rotation, and they'll tell me, is that just from sleeping wrong last night? And I tell 'em a lot of times it's not from one thing, it's from a thousand things done wrong a thousand times. Now, do you find these secretives are exclusively to one impact or could it be a series of impacts? Yeah. So, , they could be, it could, it could be from one impact that sets everything off. But basically what you're alluding to is that it's, it's from. A lifetime of playing sports and little impacts here and there. It's like BJ Palmer said, if there's a slip on a sidewalk, you know, , but it's, it's the, it's the cumulative effect. And I used to analyze a football team that I worked with. We had accelerometers in their helmets, and you could just watch the impacts occur and there was a threshold for concussion. So the coaches and I were always looking for concussive impacts. But, , it's the, what's very, very, very more important is the accumulation of sub-concussive impacts and the effect that it has on the biomechanics and the neurology, , of that upper cervical area. It's an interesting fact that as, , kids are now getting into high school, if they have the luxury to get an MRI in their brain or their includes their brainstem, is we're, we're starting to see white, changes in the white matter of the brainstem and the brain, without a history necessarily of a concussion. Or it could have been a concussion while they're in high school. But, you know, all those, all those impacts from little league, , through high school, they add up and, and, and those are the scary ones. No one is talking about that. No one is doing anything about that. But we're, , we're gonna change that. Absolutely. So. When you have these, where is the area of the spine that you do most of your time researching or analyzing or testing to see if this could be a concern? You talked about the subluxation. Is there a primary area you're looking at? Yeah, so it's gonna be the upper cervical area. It's gonna include the Pu C one and C two, and there's specific tests or cer, , specific range of motions that you can do as a quick test on the sideline if you're looking and you, and it's important if you under under. Great circumstances. If you knew these kids before they went into their athletic season and you had a baseline on them, that would be the ultimate. But there is, you know, let's say you're a mom or dad and you just join the team, there are just tests that you can do right away that lets you know if there's gonna be a compromise in the biomechanics of that upper surface area or the neurology of that upper cervical area. Yeah. So you've developed a protocol to use on the sideline in case you are suspecting this could have happened as you talked about the one time blow, or maybe you watch the same 10-year-old. I know like 10-year-old boys. There's a huge size difference and they can Oh yeah. And if you see the same kid four inches tall or hitting the same kid repetitively, Yeah. start to suspect something's not right. And you had the ability to go down and do a sideline assessment. Is that correct? Yeah. Yep. It's very easy assessment. There's not a lot of tools needed., You could have no tools or you can bring a couple tools with you. One of the easiest things to do as a chiropractor is just go through the three. Planes of motion for the neck? It would be, , I'll just go over 'em real quick. It'd be extension Flexion, which would be the occiput. It would be lateral bending, which would be occiput and Atlas, and then it would be rotation, which would be C one and C two. And, , what we're looking for is sometimes it's very obvious someone will go through rotation. I'll say, yeah, I can notice a difference when I turn to left. I can turn better to the right than I can to the left. You can make an assumption that you're gonna be, you're misaligned at your atlas. Your atlas is gonna, if you can't turn to left, it's gonna be as, , Atlas posterior on the right., As far as the assessment is concerned, you just have to do a little bit. A little bit of coaching with the person when you're looking through it, when you're working with kids, you have to tell 'em to slow down, take it easy. But once you get 'em settled down and, and tell 'em what you're looking for, you're not looking for pain. You're not looking for, , a major amount of stiffness. You're just looking for like a decreased movement going left or right. And one of the ways that I discovered over time, and this is just an incidental, is that if you're looking. To have them help you distinguish if there's a change in the range of motion, which actually means a change in the biomechanics., And you're helping them. It's called the, , patient assessment., If you have someone, for example, turn to left, you have 'em go as far to left as possible, stop, and then go a little further, and you're, that's where they're gonna tell if there's a difference. When they go to the right and they go a little further, you're able to tell, and that end range, if there's actually a deficit there. So range of motion can be used as a primary indicator of biomechanical misalignment. On the sideline, if you're really good at it, you can do a visual inspection yourself as the chiropractor. But if you can get the, , patient involved or the, or the player involved, it makes it, it makes it a really, really great system because if you make an adjustment based on that, and now they have better range of motion, let's say they were stuck in the left rotation, you adjusted their atlas, and then all of a sudden they had better range of motion going to left. You know that biomechanically, you made a correction there. And those are, those are really objective tests., You know, when you get down to the nitty gritty, it's, it's just an amazing, , amazingly easy, , task to accomplish, especially if the coach is looking or the parents are on looking, they can tell right away. And they are really into moms are the best clinicians, , around, besides the chiropractor himself. I know that this is really important to you is to get a good., Test and get up Good objective findings. And I wanna keep on this topic here for another minute because I think you've even come up with a, a tool that you can use on the sidelines too, if, if this is really your passion, correct. Yeah, that is correct. So besides doing the, , range of motion testing, so that, one of the first things that I would do besides range of motion, I would just do a simple test with a infrared, thermometer. I would take and check the left atlas and the right atlas and just to see if there's any temper, temperature differential, and all that's gonna tell us if there's a, some type of imbalance in the physiology from the left to the right. And, , a great thing, I, I have a unit that I use, it's called an Exogen, and it has a readout on the bottom of it. And you can clearly see what the temperature is between the left and the right. And everybody wants to know what their temperature is, especially the person that you're testing and especially their parents. And so when you make a determination, you can tell 'em what you're looking for. You're just checking the neurology left versus right, and if it's warmer by 0.5 degrees. From the left to the right or right to left, there's a change in the physiology and that's associated with the neurophysiology and the biomechanics of the upper, upper cervical spine. So if you took the range of motion, you went through the all three planes of range of motion, and you coupled it with the Atlas facet testing, and then if you coupled it with the grip strength testing, now you got yourself a tidy little biomechanical and neurological package. That you can use on the sideline that demonstrates to everybody watching. It gives them a causation or it gives them an idea of what it is that you're looking for and what it is that you're trying to fix. And that's what a sub-concussive,, you know, assessment is all about. You're not looking for, , a full concussion. You're looking for little parts of it. Little biomechanical changes, little neurological changes, almost like a, a preventative type of, of system. So I imagine you have a release form and paperwork you have all designed up for this so you can walk down and give it, because this is, I'm assuming this is 90% of the time your new patient that you just met, , that's gonna start practice with you, Yeah. someone you've already been taking care of for years. Correct. Correct. So let's say you're in a situation like I was taking care of little League football teams. So prior to the beginning of the season, you get informed consent that, hey, I'm the chiropractor and this is what I'm looking for. We're not gonna actually be doing,, regular chiropractic care on your. Kids. I mean, they can and, and they would and they did. But if it's just someone who is not, not even wanting anything done by the chiropractor wants, doesn't think the child needs chiropractic care, what you wanna do is frame it as a sub-concussive impact assessment plan. And all we're doing is looking for biomechanical, neurological, differences. And, , it gives you that ability to check them.. If there is an issue and you're gonna adjust them because there's also a part of the form that says we can go ahead and do that. But I like to have, , parents are gonna be present with me the entire time., Coaches are gonna be present with me the entire time. But yes, informed consent is very, very, very, very important. There is a legal aspect to the whole thing., Now let me tell you something about the environment that usually gets created once one parent has a good experience. All the parents are on board. It's, it's just like a magical happening. You know, there's always gonna be a skeptic in the crowd. There's always gonna be, say, have someone, I'm not letting a chiropractor touch my child. But once they watch that, you're interacting. And, and I might add that, you know, with, with our system, with, , with the, it's called the Jackson Cranial Cervical Junction Method Technique., There's no. Diversified or hands-on, it's all instrument based. So there's there if you're, if you're, if they're leery about having their neck cracked, it's just a, it's a very gentle process. It's just using an instrument to adjust the atlas or the occiput or C five or C one., It's very, very, , aesthetically pleasing. It doesn't look like anybody's gonna be in danger., You can see the changes right away with the Atlas facet testing or the grip strength testing, or let's say that we did, , Rombergs Rombergs testing is another one that we use. That's part of it., The child just stands on one leg and they close their eyes and they turn their head left or right, and then if they lean or fall to one side, they get their atlas adjusted and they get rechecked. And everybody, I'm telling you, when you're doing this type of work, as you know, , well you might do more of your work in the locker room. So this type of work that I was doing is basically was either with, lacrosse teams when my daughter played lacrosse or, football teams, little league football.. But everybody, all, all the eyes are on you. And so once someone experiences a good situation, everybody's on board. And you know, the big thing is, this is what I wouldn't do if I was a chiropractor working with a sports team. I wouldn't, I, I diversified care is wonderful. I do it in my office, but to the onlooker that doesn't know the history of it, the story of it, they're, it's just scary looking to someone. And especially if you're working with youth athletes., You know, it, it's, it's just concerning to some people, so that's why I like this. I love your system to do the analyzation and get the science behind what you're doing before you do it Absolutely. have something to present to patients. I know a lot of times us carpenters get kinda lazy in that kind of stuff. We just rely a hundred percent on our pal patient. We're just gonna walk through and feel that, you know, I'm, I'm the best I can get this done. Yeah. you know, you have to about the professional level. We x-ray all the players before the season starts. We have all their listings on the locker room wall, but I'm a girl dad. And I was told the moment I had a daughter that I'm gonna go to sporting events and I'm gonna be the only one in healthcare there and someone's gonna get hurt Yeah. be my job to go on the field and do something. So I carry a little trader ski in the back of my vehicle at all times, just in case. Yeah. love the. The way you have the tools to actually read the, the temperature changes. I mean, that's what we learned. Chiropractic 1 0 1 when we first started learning how to adjust and Yeah. That's Yeah. tool. So I want to dive more into your technique then, and how you do the correction of the sideline as you start to allude to. But I think this is a good spot for us to end part one. Have everybody come back for our next podcast and join us now. Now we know how to find the subluxation. Now we know how to get about doing it. Let's do part two now about the correcting the subluxation, shall we? We should. Alrighty. Well, I'm gonna wish everyone goodbye. Please like and subscribe wherever you're watching and listening to this, and come back for part two, the correction of the subluxation. Thank you, Dr. Jackson for joining us and, pleasure. Real soon. All right. Thank you sir.