Let's talk about Concussions: Part I - understanding Traumatic Brain Injury

Sidney Crosby, Chris Pronger, Mark Savard, to name a few. There has recently been a plethora of concussions and head injuries in the NHL – and with some of the game’s biggest stars on the sidelines, officials and spectators are attempting to gain more insight into the mechanism of this form of head injury. I want to step outside the hockey realm for a moment, and talk about concussions from the point of view of a physician - information relevant to fans and athletes. 

A concussion is a subset of disease (yes, it is a disease) within the category of Traumatic Brain Injury (TBI), and results from a traumatic blow that causes an impulsive force to be transmitted to the head.

We’ve all seen the hits that have lead to concussions – but what is happening that causes the damage?

If you imagine your brain is a apple bobbing inside a mug of water: there is some cushion there to help the apple absorb some shock force, but if the mug were suddenly shaken the apple would rattle around colliding with both sides. Your brain is much like this inside of your skull – but it is a much more delicate structure. 

As you have a sudden jolting force upon your head, your brain shakes within the skull. This causes injury in a multitude of ways:

  1. Direct injury to the part of the brain that is hit.
  2. Injury to the opposite side of the brain, as it is impacts the opposite side of your skull.
  3. Sheering of axons (within your brain are millions of neurons, and these are the cells responsible for making everything work!). With the sudden acceleration and deceleration these cells can become damaged, much like too much tension suddenly being placed on a string, and have the sheering force causing it to snap.
  4. Many neurochemicals are released during this trauma – often resulting in the formation of inflammation and irritation within the brain. Imagine you have strained or torn a muscle – it would be ridiculous to attempt to use that muscle immediately for fear of injuring it further.

So in a multitude of ways – this blow to the head can cause significant brain damage. While brain damage may sound like a rather harsh term – this is exactly what is occurring during a Traumatic Brain INjury.

Concussions can present with a multitude of symptoms – and often they can present immediately, or not for a few days. For that reason it is recommended that anybody who sustains a blow to the head, at any level of sport, be examined by a medical professional immediately.

Symptoms can include dizziness, headache, difficulty focusing or concentration, amnesia, depression the sensation of ‘feeling in a fog’ or feeling ‘slow’. These symptoms can persist for days, months even years! 

The most difficult component of concussions is that they can be difficult to diagnose. We don't have any tests or imaging that are helpful in the diagnosis. It is mostly based on clinical evidence as to how the patient feels. 

One of the major concerns with concussions is what we call the "second impact syndrome". The theory behind this process is that if one returns to play before their previous concussion has fully healed, another hit to the head may result in significant brain swelling that can often be fatal. This is why it is usually unclear how long someone will be on the sidelines with a concussion, as people will respond differently and it is important not to rush someone back into play.

There is a lot of research going into evaluating concussions and uncovering what we can do to help prevent and treat concussions - stay tuned for part 2 for more information! 


Shahbaz Syed, MD


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