David Camarillo – TRANSCRIPT
The word concussion evokes a fear these days more so than it ever has, and I know this personally. I played 10 years of football, was struck in the head thousands of times, and I have to tell you, though, what was much worse than that was a pair of bike accidents I had where I suffered concussions, and I’m still dealing with the effects of the most recent one today as I stand in front of you.
There is a fear around concussion that does have some evidence behind it. There is information that a repeated history of concussion can lead to early dementia, such as Alzheimer’s, and chronic traumatic encephalopathy. That was the subject of the Will Smith movie “Concussion.” And so everybody is caught up in football and what they see in the military, but you may not know that bike riding is the leading cause of concussion for kids, sports-related concussion, that is.
And so another thing that I should tell you that you may not know is that the helmets that are worn in bicycling and football and many activities, they’re not designed or tested for how well they can protect your children against concussion. They’re in fact designed and tested for their ability to protect against skull fracture. And so I get this question all the time from parents, and they ask me, “Would you let your own child play football?” Or, “Should I let my child play soccer?” And I think that as a field, we’re a long way from giving an answer with any kind of confidence there.
So I look at that question from a bit of a different lens, and I want to know, how can we prevent concussion? Is that even possible? And most experts think that it’s not, but the work that we’re doing in my lab is starting to reveal more of the details around concussion so that we can have a better understanding. The reason we’re able to prevent skull fracture with helmets is because it’s pretty simple. We know how it works.
Concussion has been much more of a mystery. So to give you a sense of what might be happening in a concussion, I want to show you the video here that you see when you type into Google, “What is a concussion?” The CDC website comes up, and this video essentially tells the whole story. What you see is the head moves forward, the brain lags behind, then the brain catches up and smashes into the skull, it rebounds off the skull, and then proceeds to run into the other side of the skull. And what you’ll notice is highlighted in this video from the CDC, which I’ll note was funded by the NFL, is that the outer surface of the brain, where it was to have smashed into the skull, looks like it’s been damaged or injured, so it’s on the outer surface of the brain.
And what I’d like to do with this video is to tell you that there are some aspects that are probably right, indicative of what the scientists think happens with concussion, but there’s probably more that’s wrong with this video. So one thing that I do agree with, and I think most experts would, is that the brain does have these dynamics. It does lag behind the skull and then catch up and move back and forth and oscillate. That we think is true.
However, the amount of motion you see in the brain in this video is probably not right at all. There’s very little room in the cranial vault, only a few millimeters, and it’s filled entirely with cerebral spinal fluid, which acts as a protective layer. And so the brain as a whole probably moves very little inside the skull.
The other problem with this video is that the brain is shown as a kind of rigid whole as it moves around, and that’s not true either. Your brain is one of the softest substances in your body, and you can think of it kind of like jello. So as your head is moving back and forth, your brain is twisting and turning and contorting, and the tissue is getting stretched, and so most experts I think would agree that concussion is not likely to be something that’s happening on this outer surface of the brain, but rather it’s something that’s much deeper towards the center of the brain.
Now, the way that we’re approaching this problem to try to understand the mechanisms of concussion and to figure out if we can prevent it is we are using a device like this. It’s a mouthguard. It has sensors in it that are essentially the same that are in your cell phone: accelerometers, gyroscopes, and when someone is struck in the head, it can tell you how their head moved at a thousand samples per second. The principle behind the mouthguard is this: it fits onto your teeth. Your teeth are one of the hardest substances in your body. So it rigidly couples to your skull and gives you the most precise possible measurement of how the skull moves. People have tried other approaches, with helmets. We’ve looked at other sensors that go on your skin, and they all simply move around too much, and so we found that this is the only reliable way to take a good measurement.
So now that we’ve got this device, we can go beyond studying cadavers, because you can only learn so much about concussion from studying a cadaver, and we want to learn and study live humans. So where can we find a group of willing volunteers to go out and smash their heads into each other on a regular basis and sustain concussion? Well, I was one of them, and it’s your local friendly Stanford football team.
So this is our laboratory, and I want to show you the first concussion we measured with this device. One of the things that I should point out is the device has this gyroscope in it, and that allows you to measure the rotation of the head. Most experts think that that’s the critical factor that might start to tell us what is happening in concussion. So please watch this video.
Announcer: Cougars bring extra people late, but Luck has time, and Winslow is crushed.I hope he’s all right. (Audience roars) Top of your screen, you’ll see him come on just this little post route, get separation, safety. There it comes at you in real speed. You’ll hear this. Announcer: The hit delivered by —
Sorry, three times is probably a little excessive there. But you get the idea. So when you look at just the film here, pretty much the only thing you can see is he got hit really hard and he was hurt. But when we extract the data out of the mouthguard that he was wearing, we can see much more detail, much richer information. And one of the things that we noticed here is that he was struck in the lower left side of his face mask. And so that did something first that was a little counterintuitive. His head did not move to the right. In fact, it rotated first to the left. Then as the neck began to compress, the force of the blow caused it to whip back to the right, so this left-right motion was sort of a whiplash type phenomenon and we think that is probably what led to the brain injury.
Now, this device is only limited in such that it can measure the skull motion, but what we really want to know is what’s happening inside of the brain. So we collaborate with Svein Kleiven’s group in Sweden. They’ve developed a finite element model of the brain. And so this is a simulation using the data from our mouthguard from the injury I just showed you, and what you see is the brain — this is a cross-section right in the front of the brain twisting and contorting as I mentioned. So you can see this doesn’t look a lot like the CDC video.