A concussion is a type of TBI (traumatic brain injury). They can be referred to as a “mild TBI” because they are not usually life-threatening. Concussions occur when a hard hit to the head or body causes the brain to move in the skull. The movement of the brain in the skull can cause injury to nerve cells within the brain. This injury is an injury to the brain cells, and thus it is a microscopic injury. This is why x-rays, CT scans, and MRI’s, are usually normal even when the child or teen has suffered a concussion. X-rays are designed to look at bone and could help show a skull fracture, which is rarely present in a typical concussion. CT’s and MRI’s are helpful to look for brain swelling and bleeding, and these are also rarely ever present in a typical concussion. Occasionally a CT or MRI would be indicated after a head injury, but thankfully, are not needed often.
When the brain cells are injured, it causes a cellular change. This cellular change causes chemicals that are typically inside cells to leak out and those that are outside cells to come in. There are also changes in the energy requirements and nerve transmission in these cells. Basically, it causes the injured cells not to work as well, which in turn leads to the symptoms of a concussion worsening with activities that cause you to “use your brain” (i.e. thinking , communicating, physical activity, etc).
Even though concussions are not typically life-threatening, they are still serious. The symptoms of a concussion can persist for longer than the typical 3-4 week recovery period if a concussion is not handled correctly. Also, a concussion can become life-threatening when a child or teen returns to contact sports participation before he/she is fully healed. While recovering from a concussion, it is much easier to sustain a worse injury to the brain with an even smaller hit. In the worst cases, this can be seen in second impact syndrome, a syndrome we have thankfully never seen but have read about in the news
In contact sports, and even just in daily activities, heads get hit by other heads, body parts, balls, sticks, rocks, walls, etc. So, how can you know when your child or teen may have a concussion? Below is what we tell our patients so that they can recognize a possible concussion after a head injury and remove themselves from the activity or play. It is normal to have a headache or soreness to the site of a head injury. Though pain at the site of the hit/injury is normal, it is NOT normal to have any of these symptoms: feeling “dazed,” “seeing stars,” feeling like his/her “bell was rung,” dizziness, nausea or vomiting, feeling slowed down and foggy, feeling disoriented, having balance difficulty or trouble walking, having light or noise sensitivity, a headache that persists or difficulty with concentration or memory. If any of these symptoms are present (even only momentarily) after a head injury (or injury to the body where the head moves back and forth rapidly), the child/teen should stop the activity or play and discuss symptoms with a parent, school nurse, coach, or athletic trainer. These symptoms (one or more) are indicative of a concussion and evaluation is needed.
References: www.cdc.gov, Giza, C. C. and Hovda, D.A., The Neurometabolic Cascade of Concussion. Journal of Athletic Training. 2001; 36(3): 228–235.