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How Do You Know If You Have a Concussion?
Dr. Mark Allen PhD

By: Dr. Mark Allen PhD on November 18th, 2019

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How Do You Know If You Have a Concussion?

Concussions  |  Brain Injury Awareness  |  Traumatic Brain Injury  |  Brain Safety & Care

If you’ve been reading about concussion diagnosis and symptoms and feel confused, that’s pretty normal. Most advice about concussions feels vague. It’s hard to know what applies to you. And if you’re like most patients, you may be second-guessing yourself and unsure of whether to see a doctor after your injury.

In this post, we’ll try to make it easier for you to know if you have a concussion and what options you have. Along the way, we’ll debunk some common myths about concussions and how you can tell if you have one.

Here’s a sneak peek at what we’ll cover:

We’ll explain what a concussion is in more depth later in this post, but for now, we’ll use this as a working definition:

A concussion is a mild traumatic brain injury sustained after a blow to the head, whiplash, or jostling of the brain. That impact to the brain causes inflammation and may damage some brain cells. That injury and subsequent inflammation leads to concussion symptoms.

Note: If you’re experiencing symptoms that won’t resolve after one or more concussions, you’re not alone and you’re not crazy. On average, our patients improve by 75% after treatment at our center specializing in post-concussion therapy. To see if you are eligible for treatment, sign up for a free consultation.

Can I Still Have a Concussion If ... ?

How do you know if you have a concussion? In this post, we'll discuss what causes a concussion, what to look for, and common misconceptions that might be confusing you.

In this first section, we’ll address some common questions that all take the form of, “Can I still have a concussion if ... ?” Some of them are tied to old myths about concussions, and some stem from misunderstandings that even many health care providers perpetuate today.

... If I Didn’t Black Out?

Yes! Someone may have told you that it’s not a concussion without loss of consciousness. But the reality is that your symptoms do not dictate whether or not you had a concussion. You don’t have to have memory loss, fainting, or any other major issue for it to be considered a concussion.

Only about 10% of concussion patients black out during their injury. The other 90% stay conscious the whole time!

... If I Didn’t Hit My Head? 

Yes, definitely. While many concussions are caused by a blow to the head, you can also get a concussion from whiplash or jostling. In those cases, the brain slams against your skull, temporarily damaging the cells and causing an inflammation response. It’s just as capable of causing symptoms as a physical hit to the head.

For example, we’ve treated people who experienced whiplash during a car accident. They didn’t hit their heads, but the damage to their brains was very real. Or, say you’re a figure skater, and your falls result in constant jostling of your brain. That could also result in a brain injury, even if you didn’t hit your head on the ice.

... If I Feel Fine the Next Day?

Mild or no symptoms does not mean you don’t have a concussion. Some people don’t notice their symptoms immediately. And the symptoms may not be extreme — it’s possible that you’ll only experience a mild headache and moderate fatigue for a few days before getting back to normal, for example.

Say you bump your head and feel totally fine afterward, and the people you’re with don’t notice any odd behavior. It’s probably not a concussion, but still has a chance of being one (especially if you’ve had brain injuries before). Sometimes, when the brain is injured, you may not experience symptoms immediately. Every brain reacts differently, so it’s important to keep an eye on how you feel for several days after a blow to the head.

Also, keep in mind there’s no such thing as a “minor” concussion. Every concussion is, in technical terms, a mild traumatic brain injury. What makes it a “bad” concussion or not mainly depends on how much your brain is affected and how bad your symptoms are. 

... If My Eyes Didn’t Show Any Change?

Yes. Most of the time, your eyes will not be a reliable source of diagnosis. That said, some baseline tests include eye-movement tracking that is capable of detecting a concussion. Unfortunately, baseline tests are not helpful unless you’ve taken them before your concussion. More on that in a bit.

So can your eyes ever indicate brain damage? They might. If both pupils are dilated, that could just be your body’s normal response to a stressful situation. If one pupil is dilated more than the other, that could indicate more serious brain trauma. It’s worth seeing a doctor immediately to rule out a traumatic brain injury.

... If the MRI or CT Scan Didn’t Show Anything?

Yes! Most regular MRI and CT scans will not show concussion damage. They’re simply not designed to detect concussion damage.

Think of it this way: Imagine you’re looking into the window of a company. The lights are on, the building is intact, and the workers are present. Externally, it seems like the company is running well. But for the purposes of our example, we’ll say that the workers don’t get along, the company’s finances have been mismanaged, and the CEO just resigned amidst a scandal. It’s actually not doing well at all.

The view you get of the company by looking at appearances (i.e., is the building there, are there people in it, etc.) is like looking at your brain with a regular MRI: It can verify that your brain structures are present and undamaged. But a regular MRI can’t tell you how well that brain is using its resources and whether your neurons are communicating the way they need to (i.e., are the employees collaborating, is the CEO leading them well, etc.). For that, you’d need an fNCI — a test we’ll talk about more in a following section.

What Are the Signs of a Concussion?

Man sitting next to his car and his bike, grabbing his head.

So what should you look for if you think you have a concussion? If you ...

  1. Experienced a hit to the head, whiplash, or jostling, and
  2. Experience one or more concussion symptoms

... then it’s likely (but not guaranteed) you have a concussion. Let’s discuss which symptoms you can get from a concussion, along with how doctors can evaluate patients when a concussion is suspected.

How You Hit Your Head: Does It Matter?

Maybe you were driving without a seatbelt when you got into a car crash. Maybe it’s a sports injury. Maybe you tripped and slammed your head on the counter. Or maybe you got knocked around at the roller coaster park. From the most frightening to the most inglorious methods of getting a concussion, the answer is the same:

You cannot have a concussion unless you hit your head, experienced whiplash, or jostled your brain enough for it to crash against your skull.

If you did experience one of those three causes of head injuries, then your chances of having a concussion are high. That said, some situations are more likely to result in serious brain injury than others.

Crash into a tree snowboarding?

Hit your head in a motor vehicle accident?

Fall off a balcony?

Those situations — and others like them — are more likely to result in a severe traumatic brain injury than, say, getting tackled during football. But having a less terrifying hit to the head doesn’t mean you should let your guard down. If you experience any symptoms of a severe traumatic brain injury (listed here), seek medical attention immediately. 

Common Symptoms of Concussion

We’ve written an extensive guide to concussion symptoms, so we won’t rehash everything here. Here’s the short version:

Signs & Symptoms of a Concussion Checklist

As you can see from the chart, there are many different kinds of symptoms of a concussion (which makes sense when you consider that your brain controls everything you do!). You might experience balance problems, overwhelm, and memory problems, while someone else might have headaches, blurry vision, and personality changes. And in young children, symptoms don’t look the same either (see items starred with an asterisk in the chart) because they can’t express what they feel as well as we can.

Doctors consider the symptoms you’re experiencing in light of your medical history. If you had it prior to head trauma — for example, depression — but it got worse after a head injury, then you should mention it as well.

Concussion Tests

There is no gold standard when it comes to concussion testing. Many doctors, for lack of better options, will order an MRI or a CT scan. Unfortunately, neither of these tests can reliably detect a concussion, although they can rule out more serious causes of your symptoms. For example, if you have a tumor, brain bleed, or aneurysm, the scans should detect that.

If it’s been several months after your injury and you’re still experiencing symptoms, then we recommend a test we use at Cognitive FX: functional neurocognitive imaging (fNCI). It’s a special kind of functional MRI that looks at how your brain uses its resources in response to stimuli.

This is as opposed to a regular MRI, which only looks at brain structure. It wouldn’t matter what you were thinking of when you got the standard MRI, the results would be the same. But for a functional MRI, the scan will change dramatically based on which regions of your brain are currently active. This distinction is critical. 

During the fNCI we administer, patients complete a set of six cognitive tasks. We use the scans to see which brain regions are involved in those tasks. Post-concussion patients exhibit clear patterns of hyperactivity or hypoactivity in the brain regions affected by their injury. When patients meet established criteria, we can say with a great degree of certainty that they suffer from post-concussion syndrome.

To learn more about other tests used during post-concussion diagnosis, please see our article on tests for post-concussion syndrome

Baseline Testing

If you play contact sports (or are in other situations that increase your likelihood of sustaining a concussion), you could complete a baseline test. A baseline test establishes what your normal functioning level is. It usually involves some basic cognitive and reaction time tests and may also involve some balance testing.

If you get a concussion after taking a baseline test, you can retake the test immediately after injury. If your scores go down significantly, then it’s likely from your concussion. 

That said, the test isn’t perfect — if it isn’t administered in exactly the same way, for example, you might not get accurate results. Some of the best baseline tests include an eye-tracking assessment. It’s worth seeing if a clinic in your area offers baseline testing with that included.

But again, baseline testing is only helpful if you do it before your concussion. After your concussion, it’s too late to be useful.

If I Have a Concussion, What Should I Do?

A young woman is smiling while riding a stationary bike.

If you think you have a concussion, it’s important not to return to normal life activities right away. The best recovery regimens involve a balance of exercise, light activity, and rest. You can slowly scale up to your previous schedule based on symptoms.

You may also want to see a doctor, both for diagnosis and for help navigating recovery. In this section, we’ll go over some pointers for recovery, along with when to see a doctor.

Active Recovery

If you sustained a concussion playing sports, do not return to play until you have fully recovered from your concussion. People who have sustained one concussion are more susceptible to getting another, especially when they haven’t yet recovered from the first. Although rare, you would also risk second impact syndrome, a fatal condition caused in a small percentage of people who sustain a second concussion while not yet recovered from the first.

Aside from that, the worst thing you can do is something called “cocooning.” Cocooning involves resting all day in a dark room while avoiding all activity (including screens). Many well-meaning doctors still give this medical advice because it’s what they were taught in school. But research over the past decade has shown that cocooning can actually increase your likelihood of long-lasting symptoms.

Here’s what you can do instead:

  1. Light physical activity for 30 minutes per day (at whatever level you can tolerate without skyrocketing symptoms)
  2. Cognitive activity like puzzles, reading, etc.
  3. Restful, calming activities (such as listening to binaural beats, medication, etc.)
  4. Normal activities for you, but at a lower intensity than usual and as tolerated
  5. Gradual return to work or school.

Do your best to get plenty of sleep (but if you have a hard time sleeping, you’re not alone — it’s a common symptom. This post might help.) 

We describe the acute concussion recovery process in depth in this post on how to treat a concussion. If you’d like extra guidance on how to work out safely, you can read our guide to post-concussion exercise.

Visit a Doctor

Seeing a doctor is not always necessary if you’ve had a concussion. That said, it depends on your tolerance for risk: If you want to be absolutely sure that you haven’t sustained a worse injury than a concussion, see a doctor. If you have unevenly enlarged pupils, or any other symptoms of a severe traumatic brain injury, you should seek medical attention immediately.

Here are some of the severe TBI symptoms listed by the NIH:

  • Convulsions or seizures
  • Headache that gets worse or won't go away
  • Inability to wake up from sleep
  • Increased confusion, restlessness, or agitation
  • Loss of consciousness lasting a few minutes to hours
  • Loss of coordination
  • Numbness or tingling of arms or legs
  • Repeated vomiting or nausea
  • Slurred speech

Otherwise, going to the doctor really depends on what you need. If your symptoms are mild and you have someone at home to watch over you, then seeing a healthcare professional may be unnecessary.

What If My Symptoms Don’t Go Away?

A young woman is sitting on her couch and grabbing her head.

If it’s been a few weeks since your injury and you’re still experiencing symptoms, it may be time to consider a concussion treatment clinic. We’ve written a full post on how to find a good clinic that you can use in your search.

Post-concussion syndrome is when you have long-lasting symptoms after a mild traumatic brain injury. Most of the time, these symptoms will not go away without treatment. The condition can be permanent, but after treatment at our clinic, 95% of our patients experience statistically verified restoration of brain function.

To learn more about how we can help you, sign up for a free consultation with our medical staff.

About Dr. Mark Allen PhD

Mark D. Allen earned a PhD in Cognitive Science at Johns Hopkins University with post-doctoral training in Cognitive Neuroscience and Functional Neuroimaging at the University of Washington. He has 15 years of research and clinical experience in fMRI, with 22 publications in tier-1 peer-reviewed scientific journals, 3 book chapters, and dozens of presentations at scientific and professional conferences in neuroscience, neuroimaging, and neuropsychology. Having collected and analyzed fMRI data from over 1,000 experimental subjects and over 300 clinically-referred patients, Dr. Allen is a pioneer and expert in the development of fMRI for use in clinical settings.