Traumatic Brain Injury

Traumatic brain injury (TBI) is a form of acquired brain injury that occurs when a sudden trauma causes damage to the brain. TBI can result when the head suddenly and violently hits an object or when an object pierces the skull and enters brain tissue. Not all blows or jolts to the head result in a TBI. The severity of a TBI may range from “mild,” which usually involves a brief change in mental status or consciousness, to “severe,” which includes an extended period of unconsciousness or amnesia after the injury.

TBI is a serious public health problem in the United States and TBIs contribute to a substantial number of deaths and cases of permanent disability. Every year, millions of people in the U.S. suffer brain injuries. More than half are bad enough that people must go to the hospital. The worst injuries can lead to permanent brain damage or death. Half of all TBIs are from motor vehicle accidents. Military personnel in combat zones are also at risk for TBIs.

Symptoms of a TBI may not appear until days or weeks following the injury. A concussion is the mildest type of TBI. It can cause a headache or neck pain, nausea, ringing in the ears, dizziness, and tiredness. People with a moderate or severe TBI may have those, plus other, symptoms, including a headache that gets worse or does not go away, repeated vomiting or nausea, convulsions or seizures, inability to awaken from sleep, slurred speech, weakness or numbness in the arms and legs, and dilated eye pupils.

Healthcare professionals use a neurological exam and imaging tests to assess TBI. Serious traumatic brain injuries need emergency treatment. Treatment and outcome depend on how severe the injury is. TBI can cause a wide range of changes affecting thinking, sensation, language, or emotions. TBI can be associated with post-traumatic stress disorder. People with severe injuries usually need rehabilitation.

TBI is caused by a blow or other traumatic injury to the head or body. The degree of damage can depend on several factors, including the nature of the event and the force of impact.

Injury may include one or more of the following factors:

• damage to brain cells may be limited to the area directly below the point of impact on the skull
• a severe blow or jolt can cause multiple points of damage because the brain may move back and forth in the skull
• a severe rotational or spinning jolt can cause the tearing of cellular structures
• a blast, as from an explosive device, can cause widespread damage
• an object penetrating the skull can cause severe, irreparable damage to brain cells, blood vessels, and protective tissues around the brain
• bleeding in or around the brain, swelling, and blood clots can disrupt the oxygen supply to the brain and cause wider damage

Common events causing traumatic brain injury include the following:

• falls
• vehicle-related collisions
• violence, such as gunshot wounds, domestic violence, or child abuse
• injuries from sports, such as soccer, boxing, football, baseball, lacrosse, skateboarding, hockey, and other high-impact or extreme sports, particularly in youth
• explosive blasts and other combat injuries

Seek emergency care after a head injury with repeated vomiting, worsening headache, seizures, slurred speech, weakness, unequal pupils, or trouble staying awake. Even milder head injuries should be evaluated if symptoms persist.