If you feel foggy, dizzy, unusually tired, forgetful, sensitive to light, or simply “not right” after a car crash, you may be wondering whether you have a concussion.
Many people assume that a concussion requires a direct blow to the head, loss of consciousness, or an abnormal brain scan. None of those things is required. A concussion can occur when the force of a collision causes the head and brain to move rapidly, even if your head never strikes anything.
What Is a Concussion?
A concussion is a brain injury, commonly called a mild traumatic brain injury or mTBI. The word “mild” describes the initial medical classification. It does not mean the symptoms are insignificant or that recovery will always be quick.
During a collision, the body may stop or change direction suddenly while the brain continues moving inside the skull. The brain can bounce, twist, or stretch. This movement can disrupt the way brain cells communicate and use energy.
In simple terms, a concussion temporarily changes how the brain functions.
The Centers for Disease Control and Prevention explains that a jolt to the head or body can cause chemical changes in the brain and stretch or damage brain cells. These changes may affect how a person thinks, feels, sees, moves, sleeps, and responds to the world around them.
You Do Not Have to Hit Your Head
A direct blow to the head can cause a concussion, but it is not necessary.
In a car crash, the head may be thrown forward, backward, or sideways very quickly. This sudden movement can place stress on the brain even when there is no visible head injury.
You also do not have to lose consciousness. Most people with a concussion remain awake during and after the collision. They may be able to talk, walk, answer questions, and even drive away from the scene.
Some people feel relatively normal at first. Symptoms may not become obvious until later that day or over the following days, especially when the person tries to work, read, drive, exercise, use a computer, or return to a busy environment.
This is one reason concussions are sometimes overlooked.
Why Most Concussions Do Not Show Up on Imaging
One of the most confusing things patients hear is, “Your scan was normal, so you do not have a concussion.”
That is not what a normal scan means.
Most concussions are primarily functional injuries rather than large structural injuries. This means the injury affects how the brain is working at a cellular and metabolic level. Brain cells may have difficulty communicating normally and managing the energy needed to perform everyday tasks.
Routine imaging is generally not designed to show these functional and metabolic changes.
What X-Rays, CT Scans, and MRIs Are Designed to Find
An X-ray shows bones. It does not show the brain or measure how the brain is functioning.
A CT scan is especially useful for identifying urgent structural problems such as bleeding inside the skull, a skull fracture, or significant swelling.
An MRI provides more detailed pictures of brain structure and may identify certain abnormalities that are not visible on a CT scan. However, a routine MRI may still appear normal when a person has a concussion.
CT scans and MRIs are important when a serious structural injury is suspected. They are not the primary way a concussion is diagnosed.
A Normal Scan Does Not Rule Out a Concussion
A normal CT or MRI can be reassuring because it may help rule out certain life-threatening injuries. It does not prove that the brain is functioning normally, and it does not rule out a concussion.
“Low-Impact” Does Not Mean “No Brain Injury”
A collision does not have to destroy a vehicle or cause a visible head wound to affect the brain.
People involved in lower-speed crashes are often told they only have sprains, strains, or other soft-tissue injuries. Those injuries may be present, but the same collision forces can also cause a concussion.
The amount of vehicle damage does not tell us exactly how much force reached a particular person’s head and brain. Head position, body position, seatbelt use, direction of impact, whether the person anticipated the collision, and many other factors may influence how the body responds.
A person can therefore have a concussion even when the collision is described as minor, the airbags did not deploy, there was limited vehicle damage, or the head never struck the steering wheel, window, or headrest.
Common Concussion Symptoms
Concussion symptoms vary from person to person. Some symptoms begin immediately, while others become more noticeable over the next several hours or days.
Physical symptoms may include:
- Headaches
- Dizziness
- Balance problems
- Nausea
- Sensitivity to light or noise
- Blurred, uncomfortable, or double vision
- Unusual fatigue
- Neck pain
- Feeling unsteady
- Motion sensitivity
- Difficulty tolerating busy stores or crowded environments
Changes in thinking may include:
- Feeling foggy, slowed down, or confused
- Difficulty concentrating
- Forgetfulness
- Trouble following conversations
- Difficulty reading
- Difficulty using phones or computer screens
- Taking longer to complete familiar tasks
- Losing track of what you were doing
- Difficulty finding the right words
Emotional and sleep-related symptoms may include:
- Irritability
- Anxiety
- Feeling unusually emotional
- Sadness
- Sleeping more or less than normal
- Difficulty falling asleep
- Waking frequently
- Feeling exhausted despite sleeping
A person does not need to have every symptom to have a concussion. Symptoms may also overlap with injuries involving the neck, eyes, inner ear, balance system, or other parts of the body. A thorough evaluation helps determine which systems may be contributing to the patient’s problems.
How Is a Concussion Evaluated?
Because a concussion usually affects brain function rather than creating an obvious structural abnormality, the evaluation focuses on how the brain and related systems are working.
A thorough concussion evaluation may examine:
- The details of the collision
- How the head and body moved
- Symptoms that appeared immediately or developed later
- Memory, attention, concentration, and processing speed
- Balance and coordination
- Eye movements and visual tracking
- Dizziness and the vestibular system
- The interaction between the neck, eyes, and balance systems
- How symptoms respond to physical or mental activity
- The effect of symptoms on work, driving, sleep, and daily life
No single test identifies every concussion or explains every symptom. The diagnosis is based on the complete clinical picture.
This is also why a quick emergency-room examination and normal imaging may not identify every concussion-related problem. Emergency departments perform the essential job of looking for injuries that could threaten a person’s life or require immediate treatment. A detailed concussion evaluation has a different purpose: determining how the brain and related systems are functioning after the immediate emergency has passed.
When Symptoms Require Emergency Attention
Although concussions are classified as mild traumatic brain injuries, some symptoms may signal a more dangerous structural injury.
Seek immediate emergency medical care if you develop:
- A severe or worsening headache
- Repeated vomiting
- Increasing confusion or unusual behavior
- Slurred speech
- Weakness, numbness, or poor coordination
- A seizure
- One pupil that appears larger than the other
- Loss of consciousness
- Extreme drowsiness or difficulty waking
- Rapidly worsening symptoms
These symptoms may require emergency imaging to look for bleeding, swelling, fracture, or another serious condition.
Why Diagnosis and Documentation Matter
If a concussion is never identified, the patient may be treated only for neck pain or headaches while important brain-related problems remain unexplained.
For example, treatment directed only at the neck may not fully address problems involving memory, concentration, eye movements, balance, sleep, or tolerance for physical activity. Different problems may require different types of care.
A clear diagnosis helps guide appropriate recommendations, rehabilitation, activity changes, and referrals. It also creates a medical record showing:
- When the symptoms began
- How the symptoms changed over time
- How they affected work and daily activities
- What testing found
- What treatment or rehabilitation was recommended
- How the patient’s condition progressed during recovery
Without this information, persistent problems may be misunderstood, minimized, or incorrectly attributed to something unrelated to the crash.
Getting the Right Evaluation
Feeling confused, foggy, dizzy, exhausted, forgetful, or unlike yourself after a collision should not automatically be dismissed because your CT scan, MRI, or X-rays were normal.
At Billings Chiropractic Injury Clinic, we evaluate the different systems that may be affected after a crash. Depending on the patient’s symptoms, this may include testing brain function, memory, concentration, balance, eye movements, the vestibular system, physical exertion tolerance, and the cervical spine.
The goal is to identify the likely sources of the patient’s symptoms, document how those symptoms are affecting daily life, and determine what care or additional referral may be appropriate.
If you are experiencing possible concussion symptoms after a car crash, a thorough evaluation may help you understand what happened and what steps to take next.
