A concussion is a functional brain injury caused by a blow or sudden acceleration and deceleration to the head, neck or body, with forces transmitted to the brain.  While the structure of the brain doesn’t change, how it functions does.

Signs of a concussion and concussion symptoms can be a bit confusing, and each person may experience these differently. Some show up immediately after injury while others present hours or even days later. Some signs and symptoms are quite benign and common, while others are considered red flags and can be an indication of a more serious brain injury.

In this article, we will share concussion signs and symptoms to be aware of, when it’s time to seek emergency care, and also how to best mitigate chronic or Persistent Concussion Symptoms (PCS).

Signs and Symptoms: What’s the Difference?

A concussion sign is something that can be observed while a concussion symptom is NOT visible, but something that the athlete or patient may experience and report.

For instance, a loss of consciousness is a sign of a concussion. You can visibly see that, after the injury, the patient loses consciousness.

A symptom of a concussion may be a headache. You can’t see a headache, but the patient can report that they have one.

People often assume that to be diagnosed with a concussion, there must have been a loss of consciousness. Although loss of consciousness is a sign of concussion, it is a very rare one, and most people do not experience this. In fact, less than 10% of concussions have this visible sign.

Seizure is another concussion sign, but this too, is very rare.

A more common sign of concussion is a blank or vacant stare. This sign alone is not enough to officially diagnose a concussion, but it is something that points us in the right direction.

Other signs of a concussion may include – delayed verbal and motor responses (where a person is slow to answer questions or follow instructions), confusion, inability to focus their attention, disorientation (ie. picking up the ball and running in the wrong direction), slurred speech, gross observable incoordination (ie. an athlete that gets up stumbling and appears off balance), inability to walk in tandem (ie. heel-toe walking), becoming emotional, and memory deficits.

Memory deficits may be shown in the form of a patient’s inability to remember a list of words that you have provided them or a true deficit such as Post Traumatic Amnesia (PTA). An example of PTA is the patient not being able to remember the first half of the game.

Concussion Symptoms and Signs


Concussion Symptoms

When it comes to the symptoms of a concussion, there are actually quite a few, 22 to be exact. Each of the following are symptoms that are asked about within the SCAT, short for ‘Sport Concussion Assessment Tool’, as part of the symptom questionnaire.

The 22 main concussion symptoms are:

  • Headache
  • Pressure in the head
  • Neck pain
  • Nauseousness or vomiting
  • Dizziness
  • Blurred vision
  • Balance problems
  • Sensitivity to light
  • Sensitivity to noise
  • Feeling slowed down
  • Feeling “in a fog”
  • Feeling “not right”
  • Difficulty concentrating
  • Difficulty remembering
  • Fatigue or low energy
  • Confusion
  • Drowsiness
  • More emotional
  • Irritability
  • Sadness
  • Nervous or Anxious
  • Trouble falling asleep

Diagnosing Concussion Symptoms

Knowing the concussion symptoms  is fine, but what does this look like in real life?

Let’s say you’re a hockey coach on the sidelines, and one of your players just took a bad hit. You call them off the ice and talk to them, but they are staring blankly at you. You know something is up and start asking some questions.

As they begin to answer, you may notice their speech is delayed, and so are some of their motor responses, throwing them off balance. They may be confused and disoriented; when you tell them to go have a seat, they walk in the wrong direction.

These are all signs of a concussion. But what if there are no signs? How do you recognize a concussion based on symptoms?

When we assess someone based on concussion symptoms, we typically use a “zero to six” rating scale, requiring the athlete to subjectively rate the symptoms they are reporting. Zero being, “I don’t have that particular symptom,” up to six, “I have that symptom and it’s the worst I could ever imagine.”

When suspecting a concussion, one or more of the 22 main symptoms may be present, although some symptoms are a little more general than others. For instance, many different conditions may cause a headache or dizziness. Due to this, diagnosis of a concussion also factors in the mechanism of injury. Was the person hit in some way? Did they undergo acceleration or deceleration of the head, neck or body? How soon after the injury did symptoms begin? In this way, we look for any of the 22 symptoms of a concussion that closely followed a significant mechanism of injury.

As you can see, diagnosing a concussion can be tricky, which is why we always advise to work with health professionals trained in concussion management.

Distinguishing Signs Of A Concussion & Symptoms from ‘Red Flags’

A concussion by itself is not a fatal event, though mismanagement of concussion can be. It’s important to recognize and distinguish concussion signs and symptoms from ‘RED FLAGS’.

RED FLAGS are signs and concussion symptoms that may point to a more serious head injury, and one that could be potentially fatal.

In the initial period (defined as the first 24-48 hours), what we are most concerned with are things like bleeding in the brain, swelling of the brain, skull fractures, neck fractures, and even detaching of the retinas in the eyes. While a concussion itself may not be fatal, these other injuries can be.

When any RED FLAGS are present or you are in anyway unsure, a patient should be immediately sent to the Emergency Department for further assessment. It is at this point they will also be assessed on the need for further imaging such as an MRI or CT scan, used to investigate for more serious structural injuries such as fractures, bleeding in the brain and swelling.

There are two main clinical prediction tools that have been developed to assist concussion management teams to decide who should and should not get a scan in the emergency department. These two main tools are the New Orleans criteria, which was developed in the United States, and the Canadian CT head rule.

At Complete Concussions, we utilize both sets of criteria because we try and cast a wide net to pick up any red flags. Because in our opinion, ANY red flag is a reason for a trip to the emergency room.

Concussion Sign


Severe or Worsening Headache

Vomiting – The New Orleans criteria states vomiting once is a warranted trip to emergency, whereas the Canadian CT Head rule says two or more episodes. We lean toward the New Orleans criteria.

Age – New Orleans criteria says anyone who is 60 years of age or older should get a CT scan, while the Canadian CT Head rule says 65+. Again, we tend to be more cautious and say if you are 60 or older, you should get checked out in the ER.

Drugs – if there was drug or alcohol intoxication reported at the time of injury, a scan should be completed.

Anterograde amnesia – Having persistent anterograde amnesia, which is the inability to form new memories after the accident (ie. the player or patient keeps asking ‘why am I am here?’).

Retrograde amnesia – Amnesia of 30 or more minutes before the impact (Canadian CT head rules).

For us at Complete Concussions, we would consider any amnesia 30 minutes before or after the injury to be a red flag.

Visible trauma above the clavicle

Signs of skull fracture – an open / visible fracture; palpable discrepancy in the bony contour; bloody ear discharge; cerebrospinal fluid draining from the ears or nose; bruising behind the ears (battle sign); bruising around the eyes (racoon eyes); facial paralysis; nystagmus (flickering of the eyes); paresthesia (numbness or tingling); abnormal pupillary reflex (when you shine a light in someone’s eye, their pupil should constrict. After a concussion, sometimes you will see pupils that stay dilated, or one pupil is larger than the other); vomiting and altered mental state. These are all signs of a possible skull fracture.

A dangerous mechanism – Defined as being struck by a vehicle or ejected from a vehicle; a fall from an elevation of three or more feet or five or more stairs.

Another thing to be concerned about is neck fractures, especially in the field. Because concussion is caused by acceleration of the head, there’s going to be a tremendous amount of force that is transmitted through the neck. If there is any concern of neck fracture, this needs to be dealt with via usual advanced emergency care protocols.

These are the red flags we look for and when we find them, we refer the patient to the nearest emergency room to mitigate any serious injury in addition to concussion.

Remember, structural imaging techniques such as MRI and CT scans are NOT used to diagnose a concussion, but rather structural brain injuries. Concussions are functional injuries, not structural ones, so you cannot see a concussion on a scan. If a patient has a scan and is told that it is ‘clear’, this means that it is clear of any structural injury as mentioned above, not concussion. Scans are NOT used to clear a patient of a concussion diagnosis!

When Are Concussion Symptoms Considered Chronic?

There are 2 main diagnostic classification standards or frameworks used to determine when concussion symptoms have become chronic.

The first is from the Diagnostic and Statistical Manual 4th Edition (DSM-IV), which states that having 3 or more concussion symptoms that last beyond three months from the injury are chronic symptoms.

The second comes from the International Classification of Diseases version 10 (ICD-10). The ICD-10 states that having 3 or more concussion symptoms 4 weeks after the initial injury would be considered chronic.

So which criteria should be followed?

At Complete Concussions, we follow the ICD-10 criteria because data shows that concussion causes an energy deficit within the brain which can persist anywhere from 3 to 4 weeks. This is considered the ‘metabolic’ recovery time zone.

Technically, we do not consider concussion symptoms chronic until the 4-week mark, but at Complete Concussions we treat you as if you are chronic from 14 days post injury. Where a patient may experience treadmill testing, vestibular and ocular motor rehab, treatment of the neck and instructions on an anti-inflammatory diet plan depending on individual assessment results.

These individualized treatment plans are started as early as 10 to 14 days post injury because the science shows that if not, you are more likely to have chronic or Persistent Concussion Symptoms (PCS). Studies show that the sooner you are assessed and treated following concussion, the far less likely you are to experience PCS.

Again, this is why we always advise to seek treatment as soon as possible. Practitioners trained in concussion management can determine if there are any red flags and if not, move forward with a treatment plan that will get you back to your sport as soon as safely possible.

Looking for concussion assessments, treatment or rehabilitation?

Complete Concussions is a network of trained multidisciplinary healthcare practitioners that collaborate with physicians to co-manage concussion injuries, helping patients and athletes safely return to learn, work and play.

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