Can You Have a Concussion With a Normal CT Scan?
Yes. A CT scan looks for emergencies, not for most concussions. What a normal scan means, why it can miss a concussion, and what to do next in Florida.
Header photo: The Bushranger, CC BY-SA 4.0 (creativecommons.org/licenses/by-sa/4.0), via Wikimedia Commons.
Yes, you can have a concussion with a normal CT scan. A head CT is built to find bleeding, swelling and skull fractures that may need urgent treatment, and most concussions do not cause damage of that kind. So a CT can "miss" a concussion simply because it was never designed to show one.
A normal CT is good news. It means the emergency team did not find an injury that needs immediate surgery or close monitoring. It does not mean the brain is uninjured. This guide explains what a CT looks for, why concussions usually do not appear on it, and what patients and treating providers in Florida can do next. It is educational only and is not medical or legal advice.
Key takeaways
- A CT scan checks for emergencies such as bleeding, swelling and fractures.
- Most concussions change how the brain works without causing changes a CT can see.
- Concussion is diagnosed mainly from the injury history, symptoms and examination.
- Symptoms after a normal CT deserve follow-up with a treating provider.
- Standardized testing can be arranged through that provider, who keeps every clinical decision.
What a head CT is designed to find
Computed tomography, or CT, uses X-rays to build cross-section pictures of the head. Emergency departments rely on it because it is fast, widely available and very good at spotting problems that can become life threatening within hours: bleeding on or in the brain, a skull fracture, significant swelling, or a shift in brain structures.
That is exactly what it should do in the first hours after an injury. The question the ER is answering is "Does this person need emergency treatment right now?" A normal result answers that question with a reassuring no. It does not answer a second question: "Is the brain working normally?"
Why a concussion usually does not show on CT
A concussion is a mild traumatic brain injury caused by a bump, blow or jolt that makes the brain move quickly inside the skull. According to the CDC, that movement can cause chemical changes in the brain and sometimes stretch and damage brain cells. These are mostly changes in function, at the level of cells and connections, rather than structural damage large enough for a CT to detect.
The National Institute of Neurological Disorders and Stroke describes mild TBI as an injury that can disrupt how brain cells communicate. That disruption can produce headaches, fogginess, dizziness, light sensitivity, poor sleep and trouble concentrating, all while every image looks normal. In other words, the symptoms are real even when the scan is clean.
A normal CT rules out an emergency. It does not rule out a concussion.
What the research shows
The TRACK-TBI research network has studied thousands of patients evaluated for TBI at US trauma centers. Its findings are a useful reminder that imaging and recovery are different measures.
These figures come from Level I trauma center patients and may not describe every injury. They do show two things clearly: a normal CT can sit alongside a real brain injury, and many people with "mild" injuries do not feel fully recovered for months. For how this plays out in personal injury records, see our article on normal CT scans in Tampa Bay injury cases.
Who gets a CT after a head injury, and who does not
Not everyone with a possible concussion gets a CT. Emergency physicians use clinical decision rules, such as the Canadian CT Head Rule, to decide who needs one. These rules weigh factors like age, vomiting, a worsening level of alertness, signs of a skull fracture and a dangerous mechanism of injury. Many people with a concussion meet none of those criteria, so they are evaluated and discharged without imaging. That is sound practice, because it limits radiation for people unlikely to have a bleed.
The result is that "no CT" and "normal CT" both leave the concussion question open. Either way, the person should know which symptoms to watch for and when to follow up. Our guide on when to go to the ER after a head injury covers the first decision in more detail.
The CDC lists these warning signs: a headache that gets worse and does not go away, repeated vomiting, weakness or numbness, decreased coordination, slurred speech, seizures, one pupil larger than the other, unusual drowsiness or inability to wake up, increasing confusion or agitation, or loss of consciousness.
Can an MRI show a concussion?
MRI is more sensitive than CT for some small injuries, such as tiny areas of bleeding or bruising, which is why it found changes in some TRACK-TBI patients whose CT was normal. Even so, many people with a concussion also have a normal MRI. A treating provider decides whether MRI or other imaging makes sense, based on symptoms and how recovery is going. No single image is the test for concussion.
What to do after a normal CT if you still have symptoms
- Follow up with a treating provider. Your primary care physician, chiropractor, physical therapist or another clinician can review how you are doing in the days after the ER visit.
- Describe the injury and every symptom. Mention any daze, memory gap or new symptom since the injury. Our guide on what to tell your doctor after a head injury can help.
- Keep a symptom log. Write down dates, what you feel, and how it affects work, sleep, screens and driving. Symptoms that appear days later are common; see concussion symptoms that show up days after a crash.
- Follow your provider's guidance on rest, return to work and return to activity.
If the injury came from a car crash, the overlap between neck strain and concussion can make symptoms easy to dismiss. Read whiplash or concussion for help sorting them out.
How standardized testing helps when imaging is normal
When the scan is normal but symptoms continue, the treating provider may want more information about how the brain is functioning. Standardized concussion testing measures areas such as attention, memory, processing speed, balance and eye movement, and compares results with expected norms. It adds structured data to the history and exam the provider already has.
Braintree Health Partners does not replace the patient's doctor or therapist. When a treating provider decides testing makes sense, Braintree's mobile team performs standardized concussion and TBI testing at that provider's office, in communities from Tampa to Jacksonville and Miami. Results are delivered as physician-reviewed diagnostic reports to the treating provider, who reaches their own clinical findings and makes every treatment decision. We diagnose. You treat.
Providers can see how mobile testing fits a practice on the For Providers page. Attorneys can learn how testing is arranged through a client's treating provider on the For Attorneys page. Patients and families can start at For Patients or read about head injury testing.
Symptoms can take days to appear; see how long after a car accident concussion symptoms can appear.
Talk with Braintree
Book a 15-minute call to see how mobile concussion testing works for your patients or clients anywhere in Florida.
Book a 15-minute callCall 813-709-3771Send a referralFrequently asked questions
Can you have a concussion with a normal CT scan?
Yes. A CT scan looks for bleeding, swelling and fractures that may need emergency care. Most concussions change how the brain functions without causing damage a CT can see, so a normal CT does not rule out a concussion.
Can a CT scan miss a concussion?
A CT is not designed to detect most concussions, so a normal result is expected in many concussion patients. The scan is still valuable because it rules out emergencies such as a brain bleed.
Will an MRI show a concussion?
Sometimes. MRI can show small injuries a CT may not, but many people with a concussion also have a normal MRI. A treating provider decides whether MRI makes sense.
How is a concussion diagnosed if scans are normal?
Concussion is diagnosed mainly from how the injury happened, the symptoms, and a clinical examination. Standardized testing of thinking, balance and eye movement can add structured information for the treating provider.
What should I do if I still have symptoms after a normal CT?
Follow up with a treating provider, describe every symptom and keep a symptom log. Return to the ER or call 911 right away for any danger sign, such as a worsening headache, repeated vomiting, slurred speech or increasing confusion.
Why did the ER not order a CT at all?
Emergency physicians use decision rules to decide who needs a CT. Many people with a concussion do not meet those criteria, so they are evaluated without imaging. Follow-up with a treating provider still matters.
Sources
- CDC: About mild TBI and concussion
- NINDS, National Institutes of Health: Traumatic brain injury
- TRACK-TBI study (Yuh et al., Annals of Neurology, 2013): MRI after a normal CT in mild TBI
This article is educational and is not medical or legal advice. Braintree makes no promise about a diagnosis or any case outcome. If this is a medical emergency, call 911.
