For David Camarillo, concussions are a personal matter.
The Stanford professor of bioengineering and of mechanical engineering played football for 10 years and estimates he was struck in the head thousands of times. However, even more damaging were the pair of concussions he sustained from bike accidents. “I'm still dealing with the effects of the most recent one today,” he says.
That's one reason why Camarillo's lab focuses on understanding and preventing head injuries. During a recent TEDx talk at Stanford, Camarillo shared some recent advances in the field of concussion research and outlined the persistent challenges facing scientists, consumers and athletes of all ages.
Research suggests the real culprit is head rotation, not just impact
While science has yet to fully understand what happens to the brain during a concussion, experts are beginning to arrive at a consensus around some of the physical dynamics at play. Conventional wisdom held that during a violent impact, the brain would briefly lag behind as the head moves forward and then rapidly catches up, setting in motion an oscillation where the brain smashes into one side of the skull and then rebounds to the other, damaging the outer surface of the brain. Camarillo says that it's more likely that the brain as a whole actually moves very little, and that the real damage comes much deeper, toward the center of the brain.
“Your brain is one of the softest substances in your body and you can think of it kind of like Jell-O,” he explained. “So as your head is moving back and forth your brain is twisting and turning and contorting and the tissue is getting stretched.”
Researchers are beginning to believe that concussions are most likely to occur when the head rotates in a certain manner. To gather data on this type of impact, Camarillo's lab outfitted Stanford football players with special mouth guards embedded with sensitive gyroscopes and accelerometers. Teeth are among the hardest substances in the body and they're closely connected to the skull, so they give the most precise measurements of how the skull moves and rotates during a collision.
Camarillo suspects that the forces that result from a violent rotation of the head rapidly transmit down to the center of the brain, dissociating a bundle of nerve fibers called the corpus callosum that connects the right and left lobes. This finding is also consistent with what researchers have learned about chronic traumatic encephalopathy, a degenerative brain disease found in athletes and others with a history of head trauma. Images of ex-professional football players' brains show that the corpus callosum and surrounding tissue have atrophied and died off over time.
Helmets designed to prevent fracture are not up to the task of preventing concussions
The good news, Camarillo says, is that it still takes a defined amount of time for the force of impact to disrupt this central wiring of your brain. “If we can slow the head down just enough so that the brain does not lag behind the skull but instead it moves in synchrony with the skull, then we might be able to prevent this mechanism of a concussion.”
The natural solution is a better helmet. Camarillo's group is collaborating with the Swedish company Hövding, maker of an innovative bicycle helmet, on a new type of headgear. Rather than a rigid plastic shell, the Hövding bike helmet functions like an airbag worn around the neck, using the same type of sensors as Camarillo's mouth guards to detect when a fall is likely and trigger an explosive inflation around the head.
Despite promising data suggesting this type of helmet can greatly reduce the risk of concussion in some scenarios, Camarillo warns that we're not likely to see one for sale in the U.S. any time soon.
“It's a pretty exciting development, but in order for us to actually realize the benefits of technology that can prevent concussion, it needs to meet regulations.”
Both bike helmets, which must be approved by the Consumer Product Safety Commission, and football helmets, which are regulated by an industry group, are tested for their ability to prevent skull fractures, not concussions. “That's an important thing to do," Camarillo says. "It can save your life, but it's not sufficient.”
So, while Camarillo's group is working to understand the internal mechanisms of head injuries, they're also focused on optimizing the standard tests and techniques to account for actions that lead to concussions as well as traumatic skull fractures. “We hope that the government can use this type of information to encourage innovation by letting consumers know how protected are you with a given helmet.”
While concussions remain scary, there is hope
“I'm much more nervous about my daughter Rose riding a bicycle. She's a year and a half old and she already wants to race down the hills of San Francisco.”
Camarillo says his personal goal is to develop technology that makes optimal use of the space inside the helmet – and that he's on the clock. “I am hopeful that we will be able to, before she is ready to ride a two-wheeler, have something available that can in fact really reduce the risk of concussion and comply with regulatory bodies,” he says.
“I hope to come back in a few years with the final story, but for now I will tell you, please don't just be afraid when you hear the word concussion. There is hope.”