Why didn’t my bike helmet prevent my TBI?


15 per cent of the approximately 18,000 traumatic brain injuries (TBIs) that occur in a year in Ontario are a result of a cycling accident. Every year in Canada, over 11,000 people die as a result of a traumatic brain injury (TBI) – using the same 15 per cent – that’s over 1600 people in Canada who die as a result of a TBI caused by a cycling accident. 85 per cent of all cyclists’ deaths in Canada involve a brain injury.

A little over five years ago, I sustained a TBI while riding my bike. It was a beautiful spring morning, and I was riding my bike to work, as I had hundreds of times before. I remember leaving my home that morning, and then waking up in the emergency room at St. Michael’s Hospital, several hours later. I was told by the doctors in the emergency department that I had been knocked off my bike, hit the ground, passed out, and taken to the ER by ambulance. Several hours later I was diagnosed with a brain injury. To this day, I have no memory of the incident.

I was wearing a bike helmet, which I always did, but my helmet did not protect me against acquiring a TBI. I’d always wondered why, and recently I got my answer. I came across a TED Talk by bioengineer (and former football player) David Camarillo, who, along with his team at Stanford University, has been able to demonstrate what really happens to our brain during a concussion, and why bike helmets, and other sports helmets, such as football helmets are not designed to protect against concussion, but rather, they are designed and tested to determine how well they protect against skull fracture.

What happens to your brain during a concussion?

The standard thinking of what happens to your brain during a concussion is that the head moves, the brain lags behind, catches up, smashes into the skull, rebounds off the skull and then proceeds to run into the other side of the skull. This dynamic is repeated many times. This understanding of what happens to the brain during concussion suggests that the brain is damaged on the outer edges.

In his Stanford University lab, Camarillo and his team, with the aid of new technology, have looked closely at what happens to the brain when it is experiencing a concussion. Their investigations suggest that the current thinking about what occurs to the brain during a concussion is not entirely accurate. Firstly, he does not believe that the brain moves around as much as current wisdom suggests. Camarillo argues that there is very little room in our cranial cavity for movement, perhaps a few millimetres, and our cranial cavity is filled with spinal fluid, which acts as a protective layer. Secondly, he suggests that the brain does not move as a whole.

Football player with ball about to fall to the ground

Our brain is one of the softest organs in our body – the consistency of Jell-O – and as the brain moves around in our skull during a concussion, it is probably twisting and turning and contorting – the tissue is getting stretched. Concussion does not appear to be something that is happening to the outer edges of the brain, but rather it is happening somewhere much deeper, in the centre of the brain.

The Laboratory – The Stanford Football Team

To help Camarillo and his team better understand what is happening to the brain during a concussion they utilized a mouth guard equipped with sensors and a gyroscope, which most experts believe can tell us what happens to the brain during a concussion. When someone is struck in the head, the mouth guard records how the skull moves at a thousand samples per second.

The study’s laboratory is the Stanford football team, young men who regularly go out and hit their heads.  This allows for rich information to be obtained when the researchers extract the data out of the mouth guard.

When the data from the mouth guard, was combined with a finite element model of the brain, developed by Svein Kleiven in Sweden, it showed that the brain of football players, who have suffered a concussion does not smash around in the skull, as current thinking would lead us to believe, but rather twists and contorts. The data shows that the greatest amount of stretching occurs very close to the centre of the brain.

What’s there? The corpus callosum, the wiring which connects the left and right hemispheres of your brain. Camarillo believes that this might be one of the most common mechanisms of concussion, the wiring is being disrupted, which causes a disassociation between your right and left brain and could explain a lot of the symptoms one sees in concussion. This is consistent with what researchers see with Chronic Traumatic Encephalopathy (CTE) – when the corpus callosum of a middle aged, former football player is viewed, and compared to an individual who does not have CTE, his corpus callosum is greatly atrophied.

Although there is a rapid transmission of forces down to the corpus callosum when the head is struck, it does take a certain amount of time. What Camarillo and his team believe is that if we can slow the head down just enough so that the brain does not lag behind the skull, but instead moves in synchrony with the skull, then we might be able to prevent this mechanism of concussion.

How can we slow the head down?

The most currently used bicycle helmet is constructed of expanded polystyrene (EPS) foam within a thin plastic shell. The EPS liner absorbs the force of an impact by deforming, while the outer shell increases the area over which the force is dissipates. The main considerations when designing a bike helmet is the size and stiffness of the helmet, which impacts how efficiently energy is absorbed. As a result of the materials used in constructing an EPS helmet, the size of the helmet has been limited to a few inches. This does not slow down the head enough to enable the brain to move in synchrony with the skull, rather than lag behind the skull. It turns out that air, in an expandable helmet would be the ideal mechanism for slowing the head down enough during impact, so that the brain moves in synchrony with the skull, rather than lagging behind.

woman wearing a skirt standing with her bike

It turns out that a company in Sweden called Hovding, is using the principle of air to give the wearer of their ‘helmet’ some extra space to prevent concussion. Hovding has created what is essentially the world’s first airbag for cyclists. The Hovding is a collar, worn around the cyclist’s neck, that uses advanced sensors, similar to the sensors used in the mouth guards described in Camarillo’s research above, that can sense the cyclist’s movement patterns and will react in case of an accident. The airbag will then inflate, fixate your neck and provide a shock absorption. In experiments conducted by Camarillo and his team they have found that the Hovding collar can greatly reduce the risk of concussion in some scenarios, compared to a standard EPS bike helmet. The Hovding is currently for sale in Europe and Japan, and is CE labelled, which means it complies with European Union safety standards, but not for sale in the United States, and alas, Canada.

In the US, bike helmets are federally regulated by The Consumer Product Safety Commission. The Commission has jurisdiction over the type of helmets they approve. The test they use in order to grant approval to a bike helmet is testing the helmets capacity to prevent skull fractures, not whether the helmet is likely to prevent concussion. In Canada, The Canadian Standards Association accredits organizations to certify that bicycle helmets meet certain standards, such as CPSC bicycle helmet standard, which uses the tests described above by Camarillo.

I contacted Hovding and asked about the availability of their helmet in Canada – alas, it is not available here. They replied that, at this time, they have not investigated helmet certification in Canada. So it might take some time to get my head into one!

Even so, any helmet is better than no helmet, so keep wearing whatever helmet you have, and wear it properly.


Modelling and Optimization of Airbag Helmets for Preventing Head Injuries,  published in The Annals of Biomedical Engineering in September 2016.

Since her TBI in 2011, Sophia has educated herself about TBI. She is interested in making research into TBI accessible to other survivors.

CTE Diagnosis – when will it happen?


Chronic traumatic encephalopathy? CTE?  Say that again? To be sure, outside the medical profession, a term such as this may be daunting. It refers to a progressive and degenerative brain disease that persists over a period of years, not that much different from Alzheimer’s, Parkinson’s, or early onset dementia. It breaks down part of the brain, causing it to deteriorate and lose mass, and in so doing, affects how a person behaves and functions.

Yet unlike other types of cognitive deficiencies, scientists know the root cause of CTE: repeated head trauma. 

photo credit: 124. The UT via photopin (license)
photo credit: 124. The UT via photopin (license)

Chronic traumatic encephalopathy was originally termed dementia pugilistica or in layman’s terms, ‘punch drunk.’ It was first noted in boxers during the 1920s who suffered from impaired movement, confusion, speech problems and tremors. (Now dementia pugilistica is recognised as a variant of CTE.) CTE was first documented in medical literature in 1996, and is caused by a number of neurological changes in the brain primarily due to a buildup of an abnormal protein known as tau which serves to stabilize cellular structure in the brain’s neurons. With repeated trauma, the tau becomes defective and begins to congregate in clumps, thereby disrupting the brain’s function.

What are the Symptoms?

It would be difficult to name a contact sport today which doesn’t involve some risk of head injury. Football, hockey, rugby, boxing and even soccer are all sports where players face the possibilities of concussions which can lead to an ABI. But until a few years ago, such injuries were not taken seriously – they were considered ‘just part of the game’ – something to be expected. So what if a player got hit on the head was maybe even knocked out? The prevailing attitude was, “You’ll be fine in a day or two, so now get back on the field, the rink, or the ring and WIN!”

It wasn’t until medical practitioners , not to mention teammates, friends and family of those afflicted began to notice long-term effects such as mood swings, depression and in the worst cases, suicides, that the seriousness of head trauma began to be taken seriously. The clinical symptoms associated with CTE vary in severity, but initial signs may include the following:

  • Deterioration in attention, concentration, memory
  • Disorientation
  • Confusion
  • Dizziness
  • Headaches
  • Lack of insight
  • Poor judgment
  • Overt dementia
  • Slowed muscular movements
  • Staggered gait
  • Impeded speech
  • Tremors
  • Vertigo

Currently, medical practitioners believe there are four distinct stages of CTE. During the first stage, an individual may suffer headaches and confusion, but by the time he or she reaches stage two, there may be evidence of social instability, erratic behavior, memory loss, depression and the initial symptoms of Parkinson’s disease. The third stage includes symptoms such as executive function problems, difficulty in judgment, speech difficulties, lack of muscular control and difficulty in swallowing. In the fourth stage, full-blown dementia occurs.

Photo credit:
Photo credit: Dead Spn

A New Breakthrough

Until a couple of years ago, the only way of testing for CTE was though conducting a postmortem on the brains of the deceased using a microscope to analyze cells.

Nevertheless, a study early in 2013 seems to have finally opened the door to diagnosing CTE in living test subjects. It was headed by Dr. Gary W. Small, an author and professor of psychiatry and biobehavioral sciences at UCLA and funded by a $100,000 grant from the Brain Injury Research Institute (BIRA).This non-profit organization in California was founded by neurosurgeon Dr. Julian Bailes and Dr. Julian Bailes, a pathologist who identified the first case of CTE in a former NFL player in 2005.

Photo credit:  sportsmd.onpointdigitalmarketing.com
Photo credit: sportsmd.onpointdigitalmarketing.com

The study was conducted on five patients between the ages of 45 and 73, all of them former NFL players with a history of at least one concussion. It made use of a radioactive biomarker that Small had co-invented for diagnosing Alzheimer’s disease. In the study, a compound known as FDDNP was injected into a vein where it circulated through the body and attached itself to any tau the brain happened to have and which could be seen by means of a scan. In all five players, the scan ‘lit up’ for tau, particularly in the areas of the brain which control memory and emotions. In addition, the tau patterns were consistent with patterns detected in post-mortems of people diagnosed with CTE. Think of a Geiger-counter!

Small felt that if scientists could begin to diagnose the disease while a patient was still alive, the method of detection could potentially lead to better understanding and treatment for those afflicted while helping to prevent future occurrences.

Dr. Robert Cantu, a senior advisor to the Head, Neck and Spine Committee at the NFL, commented:

“This is the holy grail if it works. This is what we’ve been waiting for, but it looks like it’s probably preliminary to say they’ve got it.”

While autopsy remains the only definitive means of diagnosing CTE, Small’s study has so far proven to be the most promising of several research projects, all of which aim to get inside the skull and seek out potential brain damage before it’s too late.

Sadly, it was too late for NFL football defense Dave Duerson and linebacker Junior Seau, both of whom died of self-inflicted gunshot wounds to the chest. Duerson died in February 2011, leaving behind a note requesting his brain be donated to research. Autopsies revealed both players had CTE.

Duerson’s suicide note. Photo by Marc Serota/The New York Times/Redux
Duerson’s suicide note. Photo by Marc Serota/The New York Times/Redux

And it seems some players might not want to let others know they have it. In the words of former NHL right-winger Matthew Barnaby:

(Hockey is) a big business and there’s a lot of money involved. We all know as players, we know what management thinks of guys who have had one, two, three concussions, whatever the number may be. Every time you have one more diagnosed, you’re thought of as damaged goods and your price tag when you become a free agent is going to go down. There might not be anyone come calling.

Yet Toronto Maple Leafs goaltender James Reimer feels differently:

 This is like that question, ‘Do you want to know right now the day you are going to die?’ It’s not an easy question to answer. But I think the more knowledge you have about your medical situation, the better. It helps you make more informed decisions. If you have a torn ankle, you want to know how badly torn it is. Same with your brain, if it’s damaged, you want to know how bad.

Potentially, athletes who now show signs of CTE could use the information to decide whether or not to retire and when, thus preventing further injury. But according to Bailes, a lot more research is needed before that can happen.

The Future

Concussions are being treated more seriously now than ever before. No longer are they being perceived as a mere ‘bumps on the head.’ And together with this greater awareness is an increase in corporate support.

The NFL’s latest collective bargaining agreement sets aside $100 million to put toward research, much of which is expected to go to brain injury. But so far, only $1 million has been distributed—to Boston University’s Center for the Study of Traumatic Encephalopathy.

And the issue of funding is a tricky one. Dr. Charles Bernick of the Cleveland Clinic and one who has undertaken studies on the relation between boxing and brain injuries, explained, “Doing studies like this requires funding, but if you’re heavily indebted in an agency that has a vested interest, there can be a view of a conflict of interest.

Still, it’s a start – and most definitely a step in the right direction. CTE testing on living subjects may well be “the holy grail” with respect to brain injury research, but it will take both time and money before it becomes standard practice.

In the mean time, players who have suffered multiple concussions watch for signs and wait for more research. NFL Super Bowl champ Ben Utecht composed a song ,dedicated to his wife and daughters, about an aging football player who fears he may not remember the names of his family one day due to disease from multiple concussions.