Concussion Series Part 1: What is a Concussion?

Concussions have been a hot topic in our country the last few years, especially in sports. Most people understand that a concussion is a head injury and it has commonly been referred to in the past as a “brain bruise”. The latest research has steered the conversation away from that as a comparison because it is much different than what we understand a bruise to be when we see it on our skin. If the brain is not bruised in a concussion, then what happens after a person gets hit in the head? In order to understand what happens, first we need to understand exactly what the brain is made up of and how it is protected.

The average brain weighs about 3 pounds and has the consistency of Jell-O. It is made up of mostly fat that helps to protect the nerve cells and allow those nerve cells to communicate faster. Our brains are then suspended in a fluid inside the skull; very much like how an egg yolk is suspended inside the egg white inside of the shell. If you shake an egg, the yolk inside can be damaged even if the shell itself isn’t damaged. That also happens inside of our heads with our brain. The skull is there to protect against direct blows to the brain but the brain is still able to move around inside.

Damage to our brain happens in two phases. The first phase is the tearing of our nerve cells with the acceleration and deceleration that happens to our head when we get hit. In football, this happens in mainly two ways. First is the impact of one player striking another directly in their helmet, causing the head to accelerate backward or to the side and then stopping when it reaches the end range of motion. The brain then moves inside the head and that movement can tear the nerves and damage the supporting structure. The second phase happens after the initial tearing. Our bodies only allow certain chemicals to enter into the brain tissue itself and any other chemicals can be harmful to the cells. Thus, when the supporting structures are damaged it allows many different chemicals to cross into the brain itself and those chemicals can damage the brain tissue. The second phase happens slowly and can lead to an increase or change in symptoms over the following 2-3 days.

Concussion symptoms can be varied and that all depends on what area of the brain is damaged. Our brain is sophisticated and well organized so certain areas control our movement, balance, speech, sight, hearing, and movement. This is the reason why newer concussion testing involves many different aspects and is more than just asking the individual a few basic questions such as “Can you tell how many fingers I am holding up?” and if they know their name.

In the next two articles in this series we will go over different options for treatments and how to know when our athlete is ready to return to play.