Guide · Serious Injury · Illinois

Traumatic Brain Injury Symptom Timelines: Why “I Feel Fine” Can Be Misleading

A concussion may not announce itself at the scene. How symptoms tend to appear, why that complicates a claim, and what to do about it.

By Lincoln Square Law · 8-minute read

After a crash or a fall, many people say the same thing to the police officer, the paramedic, and the adjuster: “I feel fine.” For many injuries, that is a reasonable first report. For a brain injury, it can be the start of a long misunderstanding. A mild traumatic brain injury, often called a concussion, may not announce itself at the scene. Its symptoms can appear hours or days later, and the ones that change a person’s life, such as trouble concentrating, memory lapses, irritability, and poor sleep, are the ones least likely to be noticed by a stranger or recorded in an emergency room. This guide explains the typical timeline, why it creates problems for an injury claim, and what to do about it.

Why “I feel fine” is not reassurance

A brain injury does not require a blow to the head. The rapid acceleration and deceleration of a collision can move the brain inside the skull enough to injure it. At the scene, adrenaline and shock can mask headache and confusion. Emergency departments are focused, appropriately, on life-threatening conditions such as bleeding in the brain, which is what a CT scan is designed to find. A normal CT scan rules out some serious injuries. It does not rule out a concussion, which usually does not show on standard imaging.

The Centers for Disease Control and Prevention explains that some symptoms of mild TBI and concussion may appear right away, while others may not appear for hours or days after the injury. The CDC groups those symptoms into four categories. Physical symptoms include headache, dizziness, and fatigue. Thinking and memory symptoms include difficulty concentrating. Social and emotional symptoms include anxiety and irritability. The fourth category is sleep.

The typical timeline

Every injury is different, and only a medical provider can evaluate a particular person. In general terms, the pattern many people describe looks like this.

At the scene and in the first hours. A person may be dazed, have a brief gap in memory, or feel nothing unusual. Some people have a headache or nausea that they attribute to stress.

The first days. Headache, dizziness, sensitivity to light or noise, and fatigue become more noticeable. Family members may notice that the person is slower, repeats questions, or is unusually short-tempered.

The first weeks. Many people improve. The CDC notes that most people with a mild TBI or concussion feel better within a couple of weeks. For others, problems with concentration, memory, mood, and sleep persist, and they often become most apparent when the person returns to work or school and the demands increase.

Beyond the first month. For a smaller group, symptoms continue for months. These cases typically require evaluation by specialists, such as neurologists, neuropsychologists, and therapists, and they are where the largest disputes arise.

Danger signs that require emergency care

The CDC advises seeking immediate medical attention for danger signs that include a headache that gets worse and does not go away, repeated vomiting, slurred speech or unusual behavior, and loss of consciousness. These can signal a more serious injury, and they should never be waited out.

The evidence problem this timeline creates

The delay between the event and the symptoms is a medical fact. In an injury claim, it becomes an evidence problem, because the records created in the first hours are the ones an insurer will rely on.

• The first records say “no complaints.” A police report noting no injuries, a paramedic’s note that the patient was alert and oriented, and an emergency discharge summary with a normal CT scan will all be used to argue that there was no brain injury.
• Gaps in treatment are treated as recovery. If weeks pass between the emergency room and the first neurology visit, the defense will argue that something else caused the later symptoms.
• The symptoms are invisible. A broken bone is shown on an X-ray. Concentration problems and irritability are described by the injured person and the people around them, and an insurer will call that subjective.
• Pre-existing conditions are raised. Prior headaches, anxiety, depression, or attention problems will be offered as alternative explanations.

None of this means the injury is not real. It means the proof must be built deliberately.

Getting the right care, and the right proof

• Report every symptom, every time. Tell each provider about headaches, dizziness, memory problems, mood changes, and sleep problems, even if they seem minor or unrelated. What is not reported is not recorded.
• Follow up promptly. If symptoms appear after an emergency visit, see a primary care provider and ask whether a referral to a concussion clinic or neurologist is appropriate.
• Keep a daily symptom log. Short, dated notes about headaches, missed tasks, and difficult days are far more persuasive than memories reconstructed a year later.
• Ask the people around you to write down what they see. Family members, coworkers, and supervisors often notice changes before the injured person does. Their observations can become testimony.
• Keep work and school records. Performance reviews, missed days, accommodations, and grades before and after the injury help show the change.
• Be complete about your history. Tell your providers and your lawyer about earlier head injuries or conditions. Illinois law allows recovery for the aggravation of a pre-existing condition (Illinois Pattern Jury Instructions (Civil) 30.03), and a history that surfaces later without explanation does more damage than one disclosed at the start.

How a contested brain injury is proved

When an insurer disputes a brain injury, the case usually turns on specialist evidence. A neuropsychologist can administer standardized tests of attention, memory, processing speed, and executive function and compare the results with expected norms, including built-in measures of effort. A neurologist can connect the findings to the mechanism of the crash and the course of symptoms. Advanced imaging may add support in some cases, but its use is often contested, and expert opinions in Illinois must meet the state’s foundation and general-acceptance requirements (Ill. R. Evid. 702 and 703). The strongest cases pair expert findings with the ordinary evidence described above: the symptom log, the observations of family and coworkers, and the records from work or school.

The deadline does not wait for the diagnosis

A delayed diagnosis does not delay the filing deadline. For an injury caused by a sudden, traumatic event such as a collision, the Illinois Supreme Court has held that the limitation period begins at the time of the event, even if the injured person does not yet know the full extent of the injury (Golla v. General Motors Corp., 167 Ill. 2d 353 (1995)). Most Illinois injury claims must be filed within two years (735 ILCS 5/13-202), and claims against local public entities generally within one year (745 ILCS 10/8-101). A person who first learns of a concussion months after a crash has less time than it may seem.

Talking with insurers

A brain injury can affect memory and word-finding, which makes a recorded statement to an insurer especially risky in the weeks after a crash. It is reasonable to decline a recorded statement and to refer the adjuster to your attorney. It is also wise to avoid signing a release or accepting an early settlement until the course of the injury is clear, because a release generally ends the claim, including for symptoms that have not yet appeared.

Follow up promptly and keep a written symptom record

A concussion often arrives quietly and is recorded poorly. The early records will say the person was fine, and the defense will build its case on those records. The answer is prompt medical follow-up, complete reporting of symptoms, a written record kept by the injured person and the people around them, and attention to the deadline from the date of the event.