Last Updated: April 2, 2026

A concussion is a type of traumatic brain injury that can occur from car accidents and cause symptoms including headache, dizziness, confusion, and memory problems. Recovery requires rest and gradual return to activity under medical guidance. Some concussions have delayed symptoms; document all medical care for your claim.

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Concussion After a Car Accident in Illinois: What You Need to Know

The Headache That Will Not Go Away

You were in a car accident. Maybe it was a rear-end collision on I-74. Maybe someone ran a red light at an intersection. The airbags deployed, your head snapped forward, and now — hours or days later — you have a headache that will not quit, you cannot focus at work, and the lights in your kitchen feel too bright.

You might have a concussion. And if you do, the decisions you make in the next few weeks will shape both your recovery and your legal claim.

What a Concussion Actually Is

A concussion is a mild traumatic brain injury caused by the brain moving rapidly inside the skull. In a car accident, this happens from the sudden deceleration — your skull stops but your brain keeps moving, striking the interior walls. You do not have to hit your head on anything. The whiplash motion alone can cause a concussion.

This is the part that catches people off guard. The ER may clear you. The CT scan may come back normal. CT scans are designed to detect bleeding and structural damage — they do not detect concussions. A normal CT scan does not mean your brain was not injured. It means the injury is not the kind that shows up on that particular test.

Concussion symptoms can include:

Persistent headaches
Difficulty concentrating or “brain fog”
Light and noise sensitivity
Dizziness or balance problems
Memory difficulties
Irritability and mood changes
Sleep disturbances — sleeping too much or too little
Nausea
Fatigue that does not improve with rest

Some of these symptoms appear immediately. Others develop over days or weeks. And for a significant percentage of people, they do not resolve in the “7 to 10 days” that emergency room discharge papers sometimes suggest. When symptoms persist beyond three months, doctors call it post-concussion syndrome — and it can affect your ability to work, drive, parent, and function in daily life for months or years.

Why Insurance Companies Undervalue Concussions

Insurance adjusters and their valuation software have a structural bias against concussion claims. The reason is straightforward: concussions often lack the objective medical findings that drive settlement values upward.

There is no cast. There is no surgical scar. The MRI may look normal. The adjuster’s Colossus software — the valuation tool used by more than 40 property and casualty insurers — preferences objective medical findings over subjective complaints and discounts outlier verdicts. When the primary evidence of your injury is that you cannot concentrate, that you have daily headaches, and that you have not been the same person since the accident, the software generates a number that does not reflect what actually happened to you.

Adjusters also exploit the gap between the ER visit and the onset of symptoms. If you went to the emergency room, were told your CT was normal, and did not follow up with a neurologist for three weeks, the adjuster will argue there was a gap in treatment — evidence, in their system, that the injury was not serious. The reality is that many concussion patients do not recognize their symptoms as brain injury symptoms until they try to return to work and cannot function.

As we discuss in our article on proving a brain injury when scans look normal, the challenge is building a medical and documentary record that overcomes this structural disadvantage.

Building the Medical Record That Protects Your Claim

See a neurologist or concussion specialist. Emergency room doctors are focused on ruling out life-threatening conditions — bleeding, fractures, spinal injury. They are not concussion treatment specialists. A neurologist or sports medicine physician who specializes in concussion management will perform cognitive testing, document your specific deficits, and create a treatment plan that establishes the severity of your injury in medical terms the insurance company cannot easily dismiss.

Get neuropsychological testing. This is often the most powerful evidence in a concussion claim. A neuropsychological evaluation measures processing speed, attention, memory, executive function, and other cognitive abilities against normative data for your age and education level. When the testing shows measurable deficits — you are performing in the 12th percentile on processing speed when your education and background suggest you should be in the 70th — that is objective evidence of brain injury that even Colossus has to account for.

Document everything in writing. Keep a daily symptom journal. Note what triggers your headaches, when you cannot concentrate, what tasks you used to do easily that now exhaust you. Write down conversations where you lost your train of thought. Record the days you had to leave work early or could not drive because of dizziness. This documentation does what a CT scan cannot — it shows how the concussion changed your daily life.

Do not skip appointments. Every gap in your treatment record becomes ammunition for the adjuster. If your doctor recommends weekly vestibular therapy, go every week. If you need to reschedule, document why. Gaps in treatment are one of the strongest negative value drivers in insurer evaluation systems. The adjuster will code a two-week break as evidence your symptoms resolved — even if the real reason was that you could not get a babysitter.

Our concussion checklist walks through what to tell your doctor in that first post-accident visit so the medical record accurately reflects your symptoms from the start.

Post-Concussion Syndrome: When Symptoms Do Not Resolve

Most concussions resolve within weeks. But a meaningful percentage of patients — estimates vary, but research consistently identifies 10 to 30 percent — develop persistent symptoms that last months or longer. This is post-concussion syndrome, and it fundamentally changes the value and complexity of your legal claim.

Post-concussion syndrome can mean you cannot return to your previous job. It can mean you cannot tolerate a full day of screen work. It can mean chronic headaches that no medication fully controls. It can mean personality changes that strain your relationships — irritability, emotional flatness, difficulty engaging with your children the way you did before.

From a damages perspective, post-concussion syndrome implicates future medical expenses (ongoing neurology, therapy, medication), loss of earning capacity (if you can no longer perform your previous work), and significant non-economic damages for the impact on your daily life. Under Illinois law, the defendant takes the plaintiff as they find them — IPI 30.21, the eggshell skull doctrine. If you are more vulnerable to prolonged concussion effects because of a prior head injury, your age, or your genetics, the at-fault driver is still liable for the full extent of your injury.

The Two-Year Clock

Illinois gives you two years from the date of the accident to file a personal injury lawsuit (735 ILCS 5/13-202). For concussion cases, this timeline creates a specific tension: your symptoms may still be evolving at the one-year mark, making it premature to settle — but the two-year deadline means you cannot wait indefinitely to decide whether to pursue the claim.

The practical answer is to consult an attorney early, even if you are not ready to settle. Filing a lawsuit preserves your rights without forcing an immediate resolution. And having an attorney managing the insurance company’s documentation requests, recorded statement requests, and lowball offers frees you to focus on your recovery.

Injured? Get the Help You Deserve.

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Frequently Asked Questions

Can you get a concussion from a car accident without hitting your head?

Yes. The whiplash motion alone — your head snapping forward and then back — can cause your brain to move inside the skull with enough force to produce a concussion. You do not need a direct impact to sustain a traumatic brain injury. This is one of the most common misconceptions, and insurance adjusters sometimes use it against claimants by arguing that without a head strike, there was no concussion.

How long do concussion symptoms last after a car accident?

Most concussions resolve within two to four weeks. However, 10 to 30 percent of patients develop post-concussion syndrome, where symptoms persist for months or longer. Factors that increase the risk of prolonged recovery include prior concussions, older age, loss of consciousness at the time of injury, and severity of initial symptoms. If your symptoms have not improved after three to four weeks, see a neurologist.

Will a CT scan show my concussion?

Almost certainly not. CT scans detect structural abnormalities — bleeding, skull fractures, swelling. Concussions are functional brain injuries that do not show up on CT. A normal CT scan after an accident does not mean you were not concussed. Neuropsychological testing and specialized imaging (like DTI-MRI in some cases) are better tools for documenting concussion and its effects.

How much is a concussion claim worth in Illinois?

It depends on the severity and duration of symptoms. A concussion that resolves in a few weeks with minimal treatment may be worth $15,000 to $40,000 in a clear-liability case. Post-concussion syndrome with documented cognitive deficits, ongoing treatment, and impact on earning capacity can push the value into six figures or higher. The strength of your neuropsychological testing and symptom documentation is often the determining factor.

Brain and spinal cord injuries can change your life in an instant. The Peoria personal injury attorneys fight to secure the long-term resources families need.

Concussion After a Car Accident in Illinois: What You Need to Know