What is a concussion?

A concussion is a mild traumatic brain injury that results from a bump, violent jolt or blow to your head that disrupts normal brain function. A concussion can also be caused by a hit to your body that is strong enough to cause your head to forcefully jerk backwards, forwards or to the side.

Concussions stretch and bruise nerves and blood vessels and cause chemical changes in your brain that result in a temporary loss of normal brain function. A single concussion usually doesn’t cause permanent damage to your brain. Multiple concussions over a lifetime may result in structural changes in your brain.

Concussions are not usually life-threatening. However, the effects from a concussion can be serious and last for days, weeks or even longer.

Do you have to be knocked out to have a concussion?

No, you don’t have to lose consciousness to have a concussion. In fact, most people who have a concussion never lose consciousness.

Can you get a concussion from a hit to the chin or jaw?

Yes, sure. Although the jaw or chin can absorb some of the blow, if you are hit in the right place, it can definitely cause a concussion.

What’s the difference between a concussion and a traumatic brain injury?

Really there is no difference. Both are considered injuries to the brain. These are virtually the same terms.

Who is most at risk for a concussion?

People at greater risk for concussion include:

  • Older people and children ages 4 and under due to their risk of falls.
  • Adolescents due to bike accidents and sports-related head injuries.
  • Military personnel due to exposure to explosive devices.
  • Anyone involved in a car accident.
  • Victims of physical abuse.
  • Anyone who has had a previous concussion.

Adolescents are at higher risk of concussion than any other age group. Researchers think this is because their brains are still developing. The brain is still laying down its neural pathways and adolescents’ necks are typically weaker at this age than in young adults and older people.

What causes a concussion?

Brain tissue is soft and squishy. It’s surrounded by cerebrospinal fluid, which acts as a cushion between it and the hard protective exterior, the skull. A concussion occurs when your brain bounces or twists inside your skull or experiences rapid, whiplash-type back and forth movement that causes it to collide with the inside of your skull. This brain movement stretches and damages brain cells and leads to chemical changes in the brain.

These injuries cause your brain not to function normally for a brief period of time and result in the signs and symptoms of concussion.

Motor vehicle accidents, falls, and sports injuries are common causes of concussions. Any sport that involves contact can result in a concussion.

Among children, most concussions happen on the playground, while bike riding, or when playing sports such as football, basketball, ice hockey, wrestling, or soccer.

What are the symptoms of a concussion?

The most common symptoms of concussion include:

  • Headache. (This is the most common symptom.)
  • Nausea or vomiting.
  • Confusion.
  • Temporary loss of consciousness.
  • Balance problems/dizziness/lightheadedness.
  • Double or blurry vision.
  • Ringing in the ears.
  • Sensitivity to light and noise.
  • Feeling tired or drowsy.
  • Changes in sleep patterns (sleeping much more or less than usual or can’t sleep).
  • Trouble understanding and/or concentrating.
  • Depression or sadness.
  • Being irritable, nervous, and anxious.
  • Feelings of being “just not right” or in a "fog."
  • Difficulty paying attention, forgetful, memory loss.

It’s very common for infants and toddlers to hit their head. Concussions in these little ones can be difficult to diagnose because they can’t say how they feel. Look for these signs of concussion in children:

  • Bumps on the head.
  • Vomiting.
  • Being irritable, cranky.
  • Will not eat or nurse.
  • Change in sleep pattern, sleepy at unusual times.
  • More fussy than usual, won’t stop crying despite being comforted.
  • Blank stare.

It’s always best to call your pediatrician if your child experiences a bump to their head. In fact, the American Academy of Pediatrics recommends you call your doctor for anything more than a mild head bump.

How soon do concussion symptoms appear?

Concussion symptoms usually appear within minutes of the head injury. However, some symptoms may take several hours to appear. Symptoms can change days later; others can develop when the brain is stressed with use.

What signs and symptoms of a concussion are of greatest concern? When should a person go to an emergency room?

If a child or adult experiences any of the following symptoms in the hours or days after the head injury, get them to the hospital or call 911:

  • Severe headache or a headache that continues to get worse over time.
  • Seizures or convulsions.
  • Loss of consciousness (greater than 1 minute).
  • Severe dizziness, loss of balance or problems with walking.
  • Repeated vomiting (more than once).
  • Increasing confusion, such as difficulty recognizing people or places.
  • Clear, watery discharge from the nose or ears
  • Bloody discharge from the ears.
  • Numbness, weakness or tingling in arms or legs.
  • Unusual, bizarre or irritable behavior.
  • Slurred speech.
  • Pupils that are bigger than normal or unequal in size.
  • Extreme drowsiness, difficulty waking from sleep, or fainting.

Seek emergency care if your infant has any of these symptoms:

  • Loss of consciousness.
  • Vomiting.
  • Seizures.
  • Discharge or blood coming out of the nose or ears.
  • Unable to open eyes on their own.
  • Difficulty waking from sleep.
  • Swelling of the soft spot; bruising, especially around the eyes or behind the ears; swelling of the head; skull fracture.

Does a concussion occur exactly where the blow to the head occurs? Are there worse areas of the brain to have a concussion?

The force of a hit can cause a concussion on the part of the brain that was directly hit or on the opposite side of the brain (as the brain tissue itself moves from the force of the blow and hits the opposite side of the skull).

Different areas of the brain control different functions, so blows to your head can predict your symptoms. A concussion to the back of the brain causes balance issues, fogginess, neck pain and difficulty concentrating. These symptoms usually predict a longer recovery from a concussion.

Are there certain criteria that I could see in my child, adolescent athlete or my elderly parent that would indicate that immediate medical care is needed?

Yes. Call an ambulance if your child or elderly loved one has lost consciousness for longer than one minute, is not arousable, has a possible neck injury, shows a worsening of symptoms, has numbness that lasts or has weakness on one side of their body (can’t raise arm or leg or has unequal smile). If you have any doubt, it’s always safest to not move your loved one, call your local emergency department and closely monitor your loved one until help arrives.

Last reviewed by a Cleveland Clinic medical professional on 06/02/2020.

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