During Game 1 of the Maple Leafs’ ongoing playoff series against the Florida Panthers, Leafs goaltender Anthony Stolarz was struck in the head by Panthers forward Sam Bennett.
Although Stolarz remained in the game for several minutes following the hit, he eventually skated to the bench, vomited and exited the ice. He was later stretchered out of the arena and taken to a hospital. Stolarz rejoined his teammates the following day, but will not play in Game 2 and isn’t expected to return for the series.
While it’s unclear whether he was officially diagnosed with a concussion, the incident has once again reignited concern over brain injuries in hockey.
As researchers specializing in brain injury biomechanics, we use both experimental (laboratory-based) and computational methods to investigate the biomechanical mechanisms of concussion and explore effective prevention strategies.
Cases like this underscore the importance of concussion detection, management and prevention, particularly in high-impact sports like hockey where head injuries remain a significant risk.
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Concussions and TBI in ice hockey
Traumatic brain injury (TBI), including concussion, is a growing public health concern worldwide. These injuries result from direct or indirect impacts to the head and can have both immediate and long-term health consequences.
In the United States alone, 1.6 to 3.8 million sports-related TBIs occur annually. In Canada, around 24 per cent of reported concussions are related to sports. In 2019, roughly 1.6 per cent of people in Canada — more than 400,000 people — aged 12 and older reported at least one concussion.
(AP Photo/Abbie Parr)
Ice hockey, one of Canada’s most popular sports, is associated with a particularly high risk of concussion. Around 22 per cent of Canadian ice hockey players between the ages of 10 and 25 experience at least one concussion. According to official injury reports from the British Columbia Amateur Hockey Association, concussions can occur up to 24.3 times per 1,000 player game hours.
At the professional level, the risks remain significant. Based on averages from the 2009–10, 2010-11 and 2011–12 National Hockey League seasons, approximately 5.8 concussions occurred per 100 players each season. Concussion-related salary loss also reached US$42.8 million in one year.
What happens during a concussion?
From a biomechanical perspective, a concussion occurs when the head experiences an external impact. Since the skull is very stiff and the brain has inertia, the skull moves immediately while the brain initially remains in its original position. The brain eventually catching up with the skull’s motion.
In straight-line, or translational, impacts, the skull compresses the brain at the point of contact, creating localized positive pressure. At the same time, on the opposite side of the brain, the skull’s movement creates negative pressure.
In rotational impacts — when the head is spun — the skull’s movement causes shear forces within the brain tissue, causing it to deform. Since the brain consists of different regions responsible for different functions, this tissue deformation can affect specific brain functional regions, leading to the range of symptoms associated with concussion.
Understanding concussion symptoms
Concussions can impact a range of functions, including physical, cognitive, emotional and cognitive abilities.
Typical symptoms include headache, dizziness, trouble with balance, vomiting, blurry vision, confusion, sleep issues, memory problems and even loss of consciousness.
These symptoms are commonly seen in athletes, including those in ice hockey. Among NHL athletes, the most commonly reported post-concussion symptoms, in order of frequency, are headaches, dizziness, nausea, neck pain, low energy or fatigue, blurred vision, light sensitivity, nervousness or anxiety, irritability and vomiting.
Concussions may present immediately following a head impact, or they may emerge hours or even days later. While most concussions can recover within seven to 10 days, some could last longer.
While the short-term effects typically include headache, vomiting and dizziness, the long-term effects may cause symptoms such long-term memory loss, depression and increased risk of Alzheimer’s disease.
Concussion assessment and management
Diagnosing concussions is challenging because they are not visible on traditional imaging techniques like CT scans. Instead, concussion assessments rely on clinical evaluation of symptoms.
The NHL has a concussion protocol in place that requires players to be immediately removed from the game for evaluation if one is suspected. The decision is based on observed physical, cognitive, emotional and sleep-related symptoms.
Other evaluation methods, such as the Glasgow Coma Scale (GCS), are also employed to assess TBIs and concussion. The GCS assesses the severity of TBI by evaluating eye opening, verbal response and motor response on a scale. The GCS score of 13-15 is classified as mild TBI, or concussion.
Those suspected of having a concussion should stop all activities and seek medical attention to begin concussion treatment and receive guidance on recovery and rehabilitation.
Concussion prevention and prediction
Reducing sport-related concussion rates requires a multi-faceted approach, including policy changes, stricter enforcement of rules and increased education and awareness.
Protective equipment also plays a key role. Helmets, in particular, are effective at protecting the head from injury. One study found wearing a helmet in ice hockey can reduce head linear acceleration, rotational velocity and the brain strain resulting from external impacts. Continuous improvements in ice hockey helmet design can further reduce injury risks.
To better understand and predict concussions, biomechanical researchers have developed injury metrics based on head kinematics and brain strain. Head kinematics-based injury metrics, such as peak linear acceleration and peak rotational acceleration, are derived from sensor-captured movement.
Another promising approach involves brain strain–based metrics, which use high-fidelity computational models to estimate brain tissue deformation. Since brain strain is closely associated with the risk of brain injury, these models are valuable for predicting and analyzing concussion mechanisms.
Ultimately, addressing concussions in ice hockey requires continued interdisciplinary research to better understand and address concussions in ice hockey. Protecting players from concussion is paramount to ensuring the game evolves as safely as it does competitively.
