What is a concussion?
A:The working definition used today for concussion is “a complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces” (developed by the consensus panel at the 1st International Conference on Concussion in Sport that was held in Vienna, Austria in 2001). Put simply, a concussion changes the way our brain functions – causes it to work less optimally. It may be caused either by a direct blow to the head, face, neck or elsewhere on the body with an “impulsive” force transmitted to the head. A Concussion may or may not involve loss of consciousness (loss of consciousness is not a diagnostic requirement). In fact, less than 20% of concussions result in a loss of consciousness.
What are the symptoms of concussion?
A: Some common symptoms often reported with concussive injuries include:
- Neck Pain
- Nausea or vomiting
- Loss of balance
- Poor coordination
- Trouble focusing on objects or words
- Poor concentration
- Feeling “foggy”
- Amnesia or poor memory
- “Flashing lights”
- Blurred or Double vision
- Seeing “Stars”
- Irritability or emotional changes
- Ringing in ears
- Slow to follow direction
- Decreased athletic ability
- Easily distracted
- Vacant Stare
- Drowsiness/ fatigue
- Difficulty falling asleep
- Feeling “off” or not like oneself
What happens to the brain during a concussion?
A direct or indirect blow to the head, face or jaw can cause the brain to accelerate then rapidly decelerate within the skull. This acceleration/deceleration motion can induce mechanical changes to the nerve fibers – causing them to stretch – and in turn, alter several important metabolic pathways. Though injury is apparent given the spectrum of symptoms experienced by a concussed athlete, no structural damage is typically evident on standard imagining techniques (eg. CT, MRI). Instead, these imaging methods are used to rule out more severe trauma such as bleeding within the brain or skull or fractures of the skull or neck. We understand now, more than ever, that just because we can’t see the injury, it doesn’t mean that something’s not wrong.
Current evidence suggests that the rapid stretch of nerve fibers within the brain during a concussive trauma results in the release of various neurotransmitters (signalling molecules within the brain), which trigger the initiation of a complex neurometabolic cascade. Ultimately an energy crisis ensues, and the brain is unable to produce the energy required to sustain its normal processes. These changes take place within minutes of the injury and can last for hours, days, or weeks before normalization occurs. It is thought to be this metabolic imbalance, along with other impaired physiological processes that contribute to the physical, cognitive, behavioural and emotional signs and symptoms typically seen in a concussed individual.
What is “Second Impact Syndrome”
Second Impact Syndrome is a rare, but serious consequence of head trauma, which results in rapid swelling of the brain – potentially leading to severe disability or death. Controversy exists as to whether second impact syndrome is a product of cumulative head trauma (when an athlete sustains a concussion while still suffering the effects of a previous concussion), or if it is simply a product of a single, mild traumatic brain injury.
Regardless of its cause, second impact syndrome is a severe consequence of head injury in young athletes. There should be absolutely NO return to play while an athlete is displaying signs and symptoms of a concussion, regardless of the level of competition.
Once I have had a concussion, is it easier to sustain another one?
When the brain is in a state of metabolic dysfunction (such as with a concussion) it is believed to be more “vulnerable” to subsequent trauma. That is, a relatively minor second blow to the head may produce more severe and irreversible changes in brain function. The physiologically altered brain is essentially weakened and less able to withstand or recover from a subsequent (though potentially mild) concussion. In this way, concussive injuries are thought to be cumulative, with progressively less force required to induce trauma to the brain each time (when occurring in close temporal relation). The symptoms experienced may be completely disproportionate to the mechanism of injury. What would have been two “mild” head injuries summate to form a more severe traumatic brain injury with longer lasting impairment.
Athletes often minimize the severity of concussion-like symptoms, or do not report symptoms at all following head injury. This may be because the athlete wants to continue playing and believes the symptoms are mild enough to play through. The athlete may believe having their “bell rung” is part of the game. In these situations, often the athlete, parent, coach, or trainer does not realize the significant consequences of playing with a concussion.
However – in general, when a concussion is identified early, managed properly, and return to sport is gradual, the risk to that athlete of sustaining a future concussion is not likely to be significantly different.
How do I know if I have sustained a concussion?
Concussions can be difficult to properly recognize given the wide range of symptoms & individual responses (especially for the lay person). Symptoms such as headache and dizziness are common yet can also occur in a variety of other sport-related issues (eg. dehydration, heat-related illness). To complicate things further, the appearance of symptoms may be delayed for several minutes or even hours after the initial injury.
Use this rule of thumb: If you, or your son/daughter is displaying one or more of the symptoms listed previously and there was an incident or trauma involving direct contact to the head or a “jostling/whiplash” effect, treat it as a concussion. It is important to realize that the mechanism of injury may be subtler and not as obvious as a “big hit.” An individual who is not acting normally, having difficulty remembering events or words or following instructions may have sustained an injury several hours previously. For athletes, there should be absolutely NO return to play on the same day as the injury regardless of the level of athletic performance.
Parents, coaches, and trainers should be taught that a symptom scale/checklist is a good method for identifying symptoms that may be indicative of concussion. For the team coach or trainer who knows the athlete well, it may be obvious that the athlete is struggling with simple questions and/or is acting unusual or different. Other cases are less apparent. Sideline concussion evaluations, which assess orientation, concentration, and memory, help to determine how well the athlete’s brain is working. The Pocket Concussion Recognition Tool is a valuable sideline assessment tool that can be used to evaluate the domains above, however it is not designed to take the place of a more comprehensive evaluation by a medical professional.