After you suffer a brain injury in an accident or following a trauma, you’ll likely have symptoms like memory loss or pain. Several kinds of brain injuries exist with different symptoms, though. A concussion, for instance, happens when the brain is impacted and swells. This is the most common type of brain injury, but it won’t always show up on your diagnostic tests, like CAT scans or MRIs.
Contusions, on the other hand, are a result of a direct brown to the head. A contusion, which is a bruise, can be bad enough to need surgical intervention due to the bleeding in the brain putting pressure on the nerves. In some rare cases, coup-contrecoup injuries happen, which are contusions that are so bad that they impact the brain from one side to the other.
Another interesting kind of brain injury is known as a second impact syndrome. This is essentially a brain injury that happens before the original injury has healed. For example, a football player suffering from a concussion who then gets a second concussion would have this syndrome. The second time the injury takes place can cause more widespread damage, which is why anyone with these injuries needs to be allowed to recover before participating in sports or dangerous activities again.
Source: Brain Injury Association of America, “About Brain Injury,” accessed May. 26, 2015