Traumatic brain injury usually results from a violent blow or jolt to the head or body. An object that penetrates brain tissue, such as a bullet or shattered piece of skull, also can cause traumatic brain injury.
Traumatic brain injury can have wide-ranging physical and psychological effects. Some signs or symptoms may appear immediately after the traumatic event, while others may appear days or weeks later.
Mild traumatic brain injury
Physical symptoms – Loss of consciousness for a few seconds to a few minutes, Nausea or vomiting, Problems with speech
Sensory symptoms – Sensory problems, such as blurred vision, ringing in the ears, a bad taste in the mouth or changes in the ability to smell
Cognitive or mental symptoms – Memory or concentration problems, Mood changes or mood swings, Feeling depressed or anxious
Moderate to severe traumatic brain injuries
Physical symptoms – Convulsions or seizures, Loss of consciousness from several minutes to hours
Cognitive or mental symptoms – Slurred speech, Agitation, combativeness or other unusual behavior
(mayoclinic.org)