What is a Concussion?
Concussion has become a buzzword in recent years due to the immense amount of research detailing the extremely detrimental effects of head trauma in athletes, especially in football and soccer players. Concussions are nothing new, however, the research detailing the short-term and long-term effects is growing. The evidence is clear. Concussions cause significant and often severe short-term and long-term effects, especially if they are not diagnosed early on and then evaluated and treated correctly. There are multiple names healthcare professionals use to describe concussion or head injuries, such as Traumatic Brain Injuries (TBI) and Chronic Traumatic Encephalopathy (CTE). Movies like “Concussion” have demonstrated the destructive effects that head injuries, like the ones in football or even soccer can have on people lives. In 2009, the Centers for Disease Control (CDC) reported over 248,000 sports-related head injuries, with almost a third of those injuries occurring in athletes 19 years old or younger. A concussion is defined by institutions such as the Mayo Clinic and the American Association of Neurological Surgeons as “a traumatic brain injury that causes a change in brain function.” In some cases it is even possible to have brain function deficits without having a concussion with what is called a “sub-concussive trauma.” We see this decrease in brain function with a variety of symptoms that we will list and discuss in the second part of this article.
Anatomy Affected in A Concussion
Our central nervous system (CNS) is composed of the brain and spinal cord. These structures sit suspended in a fluid known as cerebrospinal fluid, or CSF. This fluid helps keep the brain and spinal cord protected, buffered from touching the bones of the skull and spine and provides a network for waste disposal. In addition to the CSF, there are hard connective tissues know as dura. This dura is composed of three layers of tissue known as the dura mater, arachnoid mater and pia mater. These provide additional support in keeping the brain and spinal cord in the correct position. The vertebral artery and internal carotid artery stem from the neck provide a vast network to keep the brain oxygenated and provide nutrients, such as glucose.
When an impact occurs, it can force the brain itself to hit the hard bone of the cranium. When this happens, the direct impact can destroy nerve cells. We call these injuries coup-countrecoup injuries, due to the fact that the initial impact causes the brain to hit the skull on one side, which then causes the brain to collide with the opposite wall of the skull. These injuries are potentially very dangerous, since the swelling in the brain may not be visible on the injured athlete or car accident victim. In some cases head trauma can even be invisible to advanced imaging such as MRIs and CT scans.
When a head injury occurs, the force of impact causes a shift in the CSF forcing the brain to move. This movement can cause strain on the many small arteries through out brain and in some cases this tension or strain can “choke” the arteries disrupt blood flow to different areas of the brain. In addition, as the brain is shifted inside the cranium, the shearing force can cause damage and degeneration of the nerves. These injuries lead to increased inflammation and decreased function of many systems of the brain. These include and may not be limited to: focus, attention, emotional control, coordination, and intelligence.
It is important that as soon as a head injury occurs that the injured athlete be evaluated immediately. Time is of the essence and the worst thing that you can do is waiting to be evaluated and treated. Be sure to check out part two of our series on concussions, where we will talk about the signs and symptoms of a concussion, and what you need to do if you ever feel you have sustained one.
1. Hwang S, Ma L, Kawata K, Tierney R, Jeka J. Vestibular Dysfunction following Sub-Concussive Head Impact. Journal of Neurotrauma 2016.
2. Hayes JP, Bigler ED, Verfaellie M. Traumatic Brain Injury as a Disorder of Brain Connectivity
J Int Neuropsychol Soc. 2016 Feb;22(2):120-37. doi: 10.1017/S1355617715000740.
3.Giza CC, Hovda DA. The Neurometabolic Cascade of Concussion. Journal of Athletic Training. 2001;36(3):228-235.
4. The American Association of Neurological Surgeons. AANS. Available at: http://www.aans.org/patient information/conditions and treatments/concussion.aspx. Accessed March 1, 2016.
5.Centers for Disease Control and Prevention. Centers for Disease Control and Prevention 2016. Available at: http://www.cdc.gov/traumaticbraininjury/get_the_facts.html. Accessed March 1, 2016.