What is a Concussion?
A concussion is a "complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces." It is caused either by a direct blow to the head, or another body region which causes the head/neck to accelerate or decerlate. 90% do not result in loss of consciousness.
In the US, 50% of high school sports-related concussions occur in football. For female athletes, soccer is the most frequent sport associated with concussion.
How much force is required to cause a concussion?
Using data of over 57,000 impacts, the highest predictive value for concussions is:
- Angular Acceleration (rotational) - > 5,582 rad/s (picture a whiplash in a car accident)
- Linear Acceleration - > 96.1 g (force of gravity)
What are the effects of multiple "Sub-Concussive Hits?"
The research has shown that football players suffering multiple "low grade" head hits (average 1,177 hits) do not show any deficits during neurocognitive examination. Soccer players have been shown to be free of deficits and are within 100% of normative values during neurocognitive testing.
What happens to my brain when a concussion occurs?
A concussion should be thought of as a transient deficit in neurological functioning. This means that the symptoms associated with concussions (headache, dizziness, confusion, nausea, etc) are temporary, usually resolving in 5-7 days. There is no structural damage to the brain tissue (MRI and CT scans do not show any abnormalities). What occurs is what has been called an ENERGY CRISIS. The injured neurons become unable to produce the required energy for normal function. Coupled with a decreased blood flow to the brain following impact, the brain is unable to supply its own energy, or deliver fuel to create energy!
What should I do if a concussion is suspected?
If an athlete demonstrates any signs or symptoms of a concussion after an impact, they should be immediately removed from play, and should not be allowed back into play until cleared by a health practitioner. When in doubt, sit them out.
There are three reasons to sit an athlete out following a suspected concussion:
1. Delayed Onset of Symptoms - often symptoms are delayed until hours later, therefore it is difficult to know immediately whether or not a concussion has occurred. Better to be conservative.
2. Physical exertion - is known to prolong symptoms and worsen recovery - exercise worsens the energy crisis already occurring, as does elevated body temperature. In fact, cooling the body is neuro-protective.
3. Second Impact Syndrome - is believed to occur when a second concussion occurs before the first concussion has healed. It can result in more serious and even permanent deficits.
What is the recovery time of a concussion, and how do I know when to return an athlete to play?
The good news - usually concussion symptoms are gone within 7-10 days. The bad news - often symptom duration does not match the actual recovery of the affected neurons. In fact, it has been shown that full metabolic recovery takes approximately 30 days. If a second impact occurs before that 30 day period, symptoms may last up to 40 days, meaning full metabolic recovery likely won't occur until 90 days later!
In general, symptom presentation is a poor indicator of recovery. There is a real debate as to when athletes can safely return to sport.
What about the neck? How are concussions important for Chiropractors?
Up to 13% of concussed NHL players have also endured a neck injury. In addition, the neck itself may be implicated in the development of a concussion itself. Early studies have demonstrated that when the neck is stabilized and prevented from moving, a normally concussive blow does not result in a concussion. If the neck is permitted to move, that same blow will cause a concussion. Neck stiffness is the single greatest variable shown to decrease the acceleration of the head, and therefore decrease the incidence of concussions. However, neck strength alone is not enough. In the instance of a concussive blow, neck muscle activation typically occurs AFTER in the impact, therefore the protective effect of neck stiffness occurs when an athlete is AWARE the impact is occurring. This is why the athlete delivering the blow usually does not get concussed. Awareness is the most crucial factor for whether or not a concussion will occur.
For example, in soccer, intentional "heading the ball" scenarios demonstrate head accelerations well below concussion threshold ranges (5,582 rad/s) because the athlete is aware of the upcoming impact.
Baseline Concussion Testing
Baseline testing is becoming increasingly important for helping an athlete safely return to play. The purpose of the test is to establish a level of normal neurological functioning before an(other) impact occurs. Once an impact is experienced and a concussion is suspected, the athlete is monitored and cared for by a health care practitioner.
As symptoms decrease over time, a repeated neuro-cognitive test can be done, and the results compared to the baseline established pre-concussion. This is extremely important, as we know neurological functional recovery lags behind symptom recovery. When an athlete has demonstrated that the brain is functioning normally, he/she may proceed through the necessary physical steps to return to play.
Be sure to see Bayview Chiropractic's Baseline Concussion Testing section for more information. Be safe!