The American Academy of Neurology's Quality Standards Subcommittee defines a concussion as a change in mental status brought on by some sort of traumatic head injury that may or may not result in a loss of consciousness. While typical symptoms of an "uncomplicated" concussion include memory loss and confusion, in more complicated concussions, symptoms that are due to brain swelling may occur.
Focal Neurologic Deficits
A focal neurologic deficit refers to a problem with the brain's ability to function normally, damage to a nerve or a problem with the spinal cord. It can refer to a small area--such as an eyelid drooping abnormally--or an entire concept, such as memory. The type of deficit, as well as how severe it is, can provide clues as to which area of the brain or nervous system is affected. If the concussion-inducing trauma also causes brain bruising--also known as a brain contusion--focal neurologic deficits may occur. Dr. Randolph Evans of the Baylor College of Medicine writes in the medical reference UpToDate that this occurs because the bruised area of the brain becomes swollen and oxygen-deficient. Examples of possible focal neurologic signs indicating brain swelling include weakness, vision changes, or numbness in an arm or leg. Each of these symptoms is an indicator that the normal brain function has been disrupted.
Headache
An injury leading to concussion may also result in a blood vessel within the brain tearing and causing areas of the brain to fill with blood. This is called an intracranial hematoma, and is also associated with brain edema, or swelling. One symptom of an intracranial bleed is a headache that gets worse over time. This suggests that the patient has blood collecting within the brain; as more blood collects, the headache may worsen. This is a medical emergency; a patient experiencing a worsening headache should seek medical attention immediately.
Lethargy, Loss of Consciousness or Death
A feeling of intense drowsiness and being difficult to awaken are signs that a patient is experiencing lethargy. This symptom is another indicator that a patient with a concussion also has bleeding within the brain. In some cases, the lethargy worsens and the patient loses consciousness. As the patient deteriorates further, he is at risk of death from the bleeding that is causing the brain swelling. As in the case with a worsening headache, patients who have had a concussion but who begin to feel abnormally sleepy should consult with their health care provider; this is a situation in which urgent medical attention is highly recommended.
References
- "Neurology"; Practice parameter: the management of concussion in sports (summary statement); Quality Standards Subcommittee of the American Academy of Neurology; 1997
- MedlinePlus: Focal Neurologic Deficits
- UpToDate; Concussion and Mild Traumatic Brain Injury; Randolph Evans; June 2010
