How does a woodpecker avoid massive concussions?
The answer to this question has apparently been adapted by a team of doctors into a neck brace that could mitigate mild brain damage during contact sports like hockey or football. It’s called NeuroShield and it’s on sale right now. The question on everyone’s lips: does it work?
First, it is important to note that the website for NeuroShield states that the “collar does not, however, prevent concussions”. Sports-related concussions are a mild form of “traumatic brain injury”. Here’s how they happen. Your brain can slosh around inside your cranium. When you gain speed on the ice and decelerate abruptly—as in being smashed into the boards on the ice rink—your cranium stops in its movement, but your brain maintains its momentum and can impact the cranium, creating damage that can manifest on the spot as impaired consciousness, disorientation, headache, and nausea.
Talk of concussions in sports has trended in recent years, as experts have come to realize that these injuries can lead to brain damage and persistent cognitive issues. We should, however, not disregard what are called “subconcussive collisions”, meaning impacts below the severity of an actual concussion. Indeed, the medical community is interested in the long-term consequences of these collisions which may repeatedly cause damage to the brain that can lead to problems down the road. What if a simple collar could reduce their impact?
The principle behind the device is fairly easy to grasp. Imagine a vinyl backwash hose for your pool. Water is running through it. You grab a piece of it and start to strangle it with your hand. Upstream, the hose will expand, because water has a hard time flowing through the constriction. Now imagine that this hose is a vein in your head. If you found a way to constrict blood flow out of your head, your veins would be bigger and could, the theory goes, better cushion your brain during an impact. The NeuroShield presses on each side of your neck, where your jugular veins are, to do just that.
Given its 199$ retail price, we have reason to interrogate the science behind it.
Study 1: Hockey
There are only three published studies of the NeuroShield. It’ll quickly become clear that one of their main limitations is their size. In the first study, the authors randomized 15 “healthy male varsity level high school hockey players” to either wear or not wear the NeuroShield for 2 months while playing hockey. The goal was to then have them switch groups, with the non-collar wearers putting on the collar and vice versa for the rest of the season. Helmet sensors were used to make sure that no group received more impacts than the other (the two groups had to be comparable in the end), and players’ brains were assessed using functional magnetic resonance imaging (fMRI) and electroencephalography (EEG).
I asked an independent McGill neurologist about his opinion on the study, and he wrote that he was “impressed with this paper” which displayed “excellent design” and was “fairly interpreted”. However, there were “very few cases (as is typical of preliminary studies)”. Indeed, too few participants were recruited to conclude anything remotely generalizable.
The findings were that athletes who were not wearing the NeuroShield had more disruptions of the fine structure of the white matter in their brain from pre-season to mid-season, as well as changes in the connectivity of different parts of the brain. The athletes who wore the NeuroShield had no such changes from pre- to mid-season.
My issue, beyond the small sample size? For an intervention to be useful in the real world, compliance is necessary. When the teenagers who had not been wearing the NeuroShield in the first half of the hockey season were asked to now put it on, something funny happened: “more than half of the subjects who were scheduled to switch from the no collar to collar condition were not compliant, leaving only three subjects to comply with the collar use in the second half of the season”. The reasons given by the non-compliant players were that some felt irritation, one reported a slight nausea, and some simply did not want to change equipment. It is possible that the NeuroShield on sale right now has been modified from the version tested here (and known in the paper as the Q-Collar), but this degree of non-compliance and such a small sample size should give us pause.
Studies 2a and 2b: Football
From ice hockey, we move to high school football, with a study of 21 players with the collar and 21 without over the course of a single competitive season. More participants, but still a fairly small study when it comes to testing out a new technology.
In study 2a, the authors measured disruptions in the fine structure of the brain’s white matter, as they had in study 1; in study 2b, the authors submitted the same athletes to a working memory task and looked at brain activation via fMRI.
Collar wear compliance was higher this time around, though the authors of the paper note that “two of the participants assigned to the collar group refused to comply from the outset, and two were partially compliant with collar use during the competitive season”.
The findings here regarding the white matter structure were similar to those of study 1: the footballers without the collar were affected mid-season, but not those who wore it. As for the memory task, the collar group had no difference in brain activation during the task pre- versus mid-season, whereas the no-collar group had significant differences.
The neurologist I consulted called the measurements of working memory “highly relevant” and was likewise impressed with these two related studies. Meanwhile, an epidemiologist I know pointed out a number of potential issues: suboptimal statistical testing; a focus on p-values instead of effect sizes; and a showcasing of a type of analysis (pre-protocol analysis) that does not take into account compliance with the wearing of the collar and which inflates the effect the collar has (a more realistic analysis is only available as an appendix in the paper).
Overall, a very small cohort leading to interesting results that could easily have been inflated by suboptimal analyses.
Cherry-picking the woodpecker’s adaptations
Why don’t woodpeckers get concussions?
The principle behind the NeuroShield might make us believe the answer consists solely in increased blood flow to the brain, but the reasons I was able to unearth are many:
1) Their skull has spongy bones arrayed in plates, and this shock-absorbing material is more rich in the forehead.
2) Their beak can absorb some of the impact as well.
3) They have thick neck muscles.
4) Their brain is at a 90-degree angle compared to a human’s, which means the force of the impact gets distributed over a larger area, causing less stress.
5) They have less space in their skull for the brain to slosh around.
6) Their brain is smaller than ours. Because of the scaling phenomenon, an impact affects their entire brain as opposed to causing smaller areas of the brain to experience blunt trauma.
7) The impact when they drill for food is of a short duration, which makes the acceleration more tolerable.
8) Finally, they have a bone called the hyoid which wraps all the way around their skull like a seatbelt, whereas a human’s hyoid bone is under the chin and does not wrap around to the back of the head. This has led a group of researchers to speculate that, with each peck, the woodpecker’s jugular vein may be partially occluded, and this may lead to more blood inside the cranium to prevent their brain from sloshing around.
The NeuroShield promotional material as well as its first study highlight the inspiration from nature, but clearly the NeuroShield ignores most of the woodpecker’s adaptations to focus on one bit of speculation.
Rushed to market
The biggest red flag for me is how this device seemingly skipped the queue and went from two small-scale studies, in which compliance was an issue, to a product licensed and sold to the public by Bauer, a manufacturer of sports apparel.
Where are the results of larger studies? Is there long-term harm from compressing the jugular vein regularly? Is a registered vascular technologist equipped with an ultrasound machine required to ensure the NeuroShield, which comes in different sizes, is indeed compressing the jugular appropriately, as such a technologist was used in these studies? What if the NeuroShield is only used intermittently because of discomfort? Will it lead to a significant reduction in brain damage due to subconcussive impacts?
We do not have access to these answers.
As for the very plausibility of its mechanism of action, it is not as intuitive as one might like. The neurologist I spoke to agreed that the pressure inside the cranium can be increased by augmenting one of three things: the amount of cerebrospinal fluid (which occurs in a type of intracranial hypertension); the brain parenchyma (which happens with brain tumours, so not advisable for athletes); or the blood volume (which is what the NeuroShield influences). However, both a cardiologist and a neurosurgeon specialized in traumatic brain injury I consulted found the idea of retaining more blood to cushion the brain a hard one to swallow. Both said that it is the cerebrospinal fluid (CSF) that would protect the brain, not the blood. That said, the former is reabsorbed into the venous system, so perhaps constricting a major vein could impact CSF reabsorption and lead to improved brain cushioning. This mechanism of action is, at the very least, not intuitive even to medical specialists.
It is also worth noting the conflict-of-interest declarations in studies 1, 2a, and 2b. Q30 Sports Innovations financed these studies and they have “financial interests in the development of the Q-Collar” (now NeuroShield). One of their authors, David Smith, “is the inventor of the Q-Collar approach and has financial interest in the results of the current research”. This should not result in a dismissal, but we need to keep in mind that all of these studies were conducted on a unique, specific product that was meant for sale.
Are there alternatives to the NeuroShield? A stricter enforcement of the good sportsmanship rules in contact sports would help, as a study of hockey players demonstrated that concussions are mostly caused by a number of illegal and/or violent moves against an opponent on the ice. Neck stabilization and better mouth guards have been suggested as steps in the right direction, as has the counterintuitive idea of having footballers practice 5-minute tackling drills without protective equipment to increase awareness of their own vulnerability. If a concussion does happen, athletes need to listen to their doctor. A study found that nearly 16% of high school footballers who got a concussion and lost consciousness returned to play less than a day later, which could result in sustained damages. Finally, I suspect that my suggestion not to engage at all in these types of sports will be met with loud insults from a large segment of the population, but it must be stated and debated.
Conclusion
As it is, the NeuroShield has a questionable mechanism of action and too little evidence behind it, and nothing at all on whether or not it may cause harm in the long term. The non-compliance with its wearing in preliminary studies is notable and its price tag cannot easily be dismissed. While the NeuroShield may indeed work to decrease brain damage due to subconcussive impacts, what it needs is bigger studies, not a place on retail shelves.
Caveat emptor.
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