A concussion is a type of severe brain injury that impairs brain function. Headaches and issues with focus, memory, balance, and coordination are common side effects. A hit to the head is frequently the cause of a concussion. However, a concussion can also be caused by a violent blow to another part of the body such as when someone falls onto their head from a height or gets kicked in the head with a foot. Consequences may not appear for several days after the accident. Concussions can be difficult to diagnose because there are no signs or symptoms that will tell you if a person has suffered a concussion. The only way to know for sure is with medical tests and imaging studies. Other disorders that can have similar symptoms include epilepsy, migraine headaches, chronic fatigue syndrome, depression, alcohol abuse, vitamin deficiencies, and dementia. A health care provider will be able to make an accurate diagnosis based on all of the information given about the patient's condition combined with the results of any necessary testing. There are three types of concussions: mild, moderate, and severe. Symptoms vary depending on the severity of the concussion. With a mild concussion, the individual may experience confusion, irritability, dizziness, lightheadedness, headache, stomach pain, feeling tired, and problems with vision or hearing.