What is Traumatic Brain Injury (TBI)?

A traumatic brain injury occurs when an external force causes brain dysfunction, ranging from mild concussions to severe, life-altering trauma.

2.8M+

annual TBI-related emergency visits in the US

— CDC
#1

leading cause of death and disability for adults under 40

40%

of all TBIs are caused by falls

— CDC

Medical Definition

What experts say about TBI

Traumatic Brain Injury (TBI) is defined as "an alteration in brain function, or other evidence of brain pathology, caused by an external force."

— Centers for Disease Control and Prevention (CDC)

Common Causes of TBI

How traumatic brain injuries typically occur

Falls

The leading cause of TBI, especially in young children and adults over 65.

40% of all TBIs

Vehicle Accidents

Leading cause of TBI-related hospitalizations for young adults ages 15-44.

~20% of TBIs

Assaults & Violence

Includes physical assaults, gunshot wounds, and shaken baby syndrome.

~10% of TBIs

Sports Injuries

Common in contact sports like football, soccer, hockey, and boxing.

~15% of TBIs

The Biological Process

What happens to the brain during and after trauma

1

Primary Injury

The initial physical damage occurring at the moment of impact — bruising, tearing, or bleeding of brain tissue.

Occurs instantly
2

Secondary Injury

A cascade of biochemical processes triggered by the initial trauma — swelling, inflammation, and cell death.

Hours to days after
3

Recovery & Neuroplasticity

The brain's ability to reorganize and form new neural connections to compensate for damaged areas.

Weeks to years

TBI vs Other Conditions

How TBI differs from other brain injuries

Condition Cause Brain Involvement Typical Severity
TBI External force Always Mild to Severe
Concussion Blow to head / whiplash Yes (mild form of TBI) Mild
Stroke Blood clot or bleed Yes Variable
Anoxic Brain Injury Oxygen deprivation Yes Severe

When to Seek Immediate Help

Emergency signs after head trauma

Worsening headache

Repeated vomiting

Unequal pupil size

Seizures

Cannot be awakened

Slurred speech

Learn more about TBI: Types of TBIRecovery ProcessTBI & Mental Health
This information is for educational purposes only and does not constitute medical advice. If you suspect a head injury, seek immediate medical attention.