A concussion is a brain injury resulting from an abrupt hit to the head. It causes the head and brain to move back and forth quickly, resulting in a chemical change in the brain.

It may be difficult to determine if someone has suffered a concussion. The U.S. National Library of Medicine says key symptoms of concussion include:

• Convulsions or seizures
• Drowsiness or inability to wake up
• A headache that gets worse and does not go away
• Weakness, numbness or decreased coordination
• Repeated vomiting or nausea
• Confusion
• Slurred speech
• Loss of consciousness

Source: HealthDay