How can I tell if a head injury is serious or not?

Any head injury, no matter how minor, has the potential to be serious, so when it doubt have it checked out. A temporary change in mental status (confusion, disorientation) is often a sign of concussion. Loss of consciousness is caused by the disruption of the long tracts that reach down into the brainstem and may signal a more serious injury. Find out more about brain and spine injuries.