Traumatic Brain Injury (TBI) After a Car Accident: A Complete Guide

A traumatic brain injury is one of the most serious injuries a person can suffer in a motor vehicle crash. Unlike a broken bone, a TBI can be invisible on the outside while causing lasting changes to memory, mood, and the ability to work. This guide explains what a TBI is, how car accidents cause them, how doctors grade their severity, and what to watch for in the days after a crash.

What Is a Traumatic Brain Injury?

A traumatic brain injury (TBI) is a disruption in the normal function of the brain caused by a bump, blow, or jolt to the head, or by a penetrating head injury ¹. In a car accident, the brain can be injured even without the head striking anything, because the rapid acceleration and deceleration of a crash cause the brain to move violently inside the skull.

TBIs are a major public health problem. According to the Centers for Disease Control and Prevention (CDC), there were 68,663 TBI-related deaths in 2023, which works out to more than 190 deaths every day ¹. In 2020 there were roughly 214,110 TBI-related hospitalizations, and those figures do not count the far larger number of people treated and released from an emergency room or never treated at all ¹.

Motor vehicle crashes are one of the leading causes of TBI, alongside falls, assaults, and firearm injuries ². The forces involved in a crash, even at moderate speeds, are more than enough to injure the brain.

How Car Accidents Cause Brain Injuries

A TBI in a crash usually happens through one of two mechanisms, and often both:

• Impact injury. The head strikes the steering wheel, window, dashboard, or another object, or an object penetrates the skull.
• Acceleration and deceleration injury. The vehicle stops suddenly but the brain keeps moving, slamming against the inside of the skull. This can bruise the brain on both the front and back, a pattern known as a coup-contrecoup injury, and stretch or tear nerve fibers throughout the brain.

Rear-end collisions, head-on crashes, and rollovers all generate these forces. A person does not have to lose consciousness or strike their head to sustain a concussion, which is the most common form of TBI.

TBI Severity: Mild, Moderate, and Severe

Doctors classify TBI severity using the Glasgow Coma Scale (GCS), a standardized 3 to 15 point scale that measures eye, verbal, and motor responses ³. The total score places the injury into one of three categories ³:

• Mild TBI (GCS 13 to 15). Often called a concussion. There may be brief or no loss of consciousness, but symptoms can still be significant and long lasting.
• Moderate TBI (GCS 9 to 12). Longer loss of consciousness and more pronounced symptoms.
• Severe TBI (GCS 3 to 8). A score of 8 or lower indicates coma and an inability to protect the airway ³.

The word "mild" is misleading. A mild TBI is still a brain injury, and a meaningful number of people with concussions have symptoms that persist for weeks, months, or longer.

Symptoms to Watch For

TBI symptoms can appear immediately or may be delayed for hours or days as swelling develops. Mayo Clinic groups them into physical, sensory, and cognitive or emotional categories ⁴:

• Physical: headache, nausea or vomiting, fatigue, dizziness, loss of balance, and trouble speaking.
• Sensory: blurred vision, ringing in the ears, sensitivity to light or sound, and a bad taste in the mouth.
• Cognitive and emotional: confusion, memory or concentration problems, mood swings, anxiety, depression, and sleeping more or less than usual.

Warning signs that require emergency care include a headache that gets worse or will not go away, repeated vomiting, seizures, slurred speech, weakness or numbness, dilated pupils, and worsening confusion ⁴. Anyone who may have struck their head in a crash should be evaluated, even if they feel fine at the scene.

Diagnosis and Treatment

Diagnosis usually begins with a neurological exam and the Glasgow Coma Scale, followed by imaging such as a CT scan to look for bleeding, bruising, or swelling ⁴. Standard CT and MRI scans can appear normal even when a real concussion is present, which is one reason mild TBI is sometimes missed.

Treatment depends on severity. Mild TBIs are often managed with rest and a gradual return to activity. Moderate and severe injuries may require hospitalization, medication to limit secondary damage, and in some cases surgery to relieve pressure or remove a blood clot ⁴. Many survivors of moderate and severe TBI need rehabilitation, including physical, occupational, speech, and cognitive therapy.

Why a TBI Matters After a Crash

A brain injury can affect your ability to work, drive, and care for your family long after the visible injuries heal. Because the symptoms are often invisible and can be delayed, a prompt medical evaluation does two things at once: it protects your health, and it creates a documented record that connects the injury to the crash. Keep every record, follow your treatment plan, and report any new or worsening symptoms to your doctor right away.

If you or a loved one may have suffered a brain injury in a car accident, see a medical professional immediately. This guide is general information and is not medical advice.

Sources

1. Centers for Disease Control and Prevention (CDC), "Facts About TBI." https://www.cdc.gov/traumatic-brain-injury/data-research/facts-stats/index.html

2. Centers for Disease Control and Prevention (CDC), "TBI Data." https://www.cdc.gov/traumatic-brain-injury/data-research/index.html

3. Jain S, Iverson LM. "Glasgow Coma Scale." StatPearls, National Library of Medicine (NCBI). https://www.ncbi.nlm.nih.gov/books/NBK513298/

4. Mayo Clinic, "Traumatic brain injury: Symptoms and causes." https://www.mayoclinic.org/diseases-conditions/traumatic-brain-injury/symptoms-causes/syc-20378557