Doctor's Notes on Concussion
Concussion describes a mild traumatic brain injury that causes functional changes in brain function but does not lead to structural damage to the brain. The loss of function is short-lived and goes away on its own. Trauma to the head from any cause, such as an accident or sports injury, is the cause of a concussion.
Symptoms of a concussion may be severe or very subtle and hard to describe, even by the affected person. These can include headache, loss of consciousness, mild confusion, nausea, dizziness, irritability, slowing of reaction times, and difficult concentrating or feeling that one’s thoughts are “foggy.” Other associated symptoms and signs can include changes in sleep pattern (either being unable to sleep or excessive sleep), and reduced tolerance of bright lights or loud sounds.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.