Physiology of a Concussion
By General Info
A concussion is a traumatic brain injury (TBI) that is caused by something hitting the head, or another injury that shakes the brain inside the skull. The brain has a layer of spinal fluid around it to aid with movement and the skull houses the brain and is also used for protection. At times, this is not enough protection for the brain when it is shaken or moved violently, causing it to hit the hard skull. The brain then bounces off one side of the skull and impacts the opposite side. With this action, the brain is impacted on two different sides causing further damage. The force of the brain hitting the skull produces contusions (bruises) in the brain. Nerve cells inside the head are damaged and no longer able to send signals to other regions of the brain or throughout the body. The body uses cerebral blood flow found in the spinal column to transport nutrients and energy to the brain. A concussion slows cerebral blood flow, making it difficult for the brain to repair injured areas and return to a stable state without sufficient blood supply. These changes temporarily alter the autonomic nervous system and circadian rhythm (sleep cycle). Once a concussion occurs, the person may experience a wide range of symptoms that are classified into 4 categories: physical, cognitive, emotional and sleep-related (see figure 1).