What is a concussion?

• A. A bruising of the skull
• B. A minor ankle sprain
• C. A dehydration effect
• D. A brain injury caused by a blow to the head

Answer: (D)

A concussion is a brain injury caused by a blow to the head (or a force that makes the head move rapidly). The key idea is that the damage and symptoms come from the brain’s function being disrupted, not from a visible bone injury. You can have a concussion without a skull bruise, and it isn’t about an ankle sprain or dehydration. A skull bruise is a bone injury on the outside, while a concussion reflects how the brain is affected by the impact. An ankle sprain or dehydration relate to different parts of the body or different problems altogether. So the description that identifies a brain injury caused by a blow to the head is the best fit.