You know it when you see it, yet it’s still hard to define.
While many people can recognize a concussion when they see it, it can actually be a challenge to define exactly. That’s partially because a concussion is another name for a “mild” traumatic brain injury (TBI)—and it’s not always easy to determine what counts as mild.
“There are a lot of definitions of what a concussion is. It’s kind of mind-boggling; it sort of adds to the confusion of what concussion is,” says Steven Flanagan, MD, chair of the Department of Rehabilitation Medicine at NYU Langone Health.
The Centers for Disease Control and Prevention (CDC) defines a TBI as a “bump, blow or jolt to the head … that disrupts the normal function of the brain,” and if it’s mild, it simply results in “a brief change in mental status or consciousness.” This still leaves some room for interpretation: What is brief? What is normal?
“If there’s loss of consciousness, by definition, it has to be less than 30 minutes,” says Dr. Flanagan, “and the symptoms generally resolve within hours, days, weeks, [or] sometimes a little bit longer.”
When loss of consciousness is prolonged, then it’s considered a moderate or severe TBI. These are life-threatening emergencies and they can cause long-term effects on the body. Thankfully, severe TBIs are much less common than mild ones, or concussions. (Here are warning signs that a TBI is an emergency.)
A concussion is often defined by its symptoms, such as memory and thinking problems, mood changes, headaches, sleepiness, and sensitivity to light or noise. (Learn more symptoms of concussion here.) However, it helps to understand what causes a concussion. While a severe TBI may include penetration of the skull and brain—an obvious injury—a concussion can be a lot more subtle.
“The brain is actually very soft. It has the consistency of formed Jello,” says Dr. Flanagan. “When your head gets jerked backwards and forwards and sort of to the side, the brain can actually compress on itself, stretch, [and] twist a little bit.”
This unnatural twisting and stretching doesn’t just hurt the brain tissue, but it stretches out a part of your nerve cells called axons. “The axons are like telephone wires, or like wires in a computer network. If they’re stretched, there’s going to be a period of time where they’re just not gonna work properly, and they’re not gonna transmit information properly,” says Dr. Flanagan.
These injuries to the axons is what leads to the telltale signs of concussion. For example, if the coordination between your eyes and ears are off because of axon malfunction, your balance is going to be off.
But the good news about a concussion is that most people can recover without any major issues. Learn more here about concussion recovery here.
Dr. Flanagan is the chair of the Department of Rehabilitation Medicine at NYU Langone Health. He specializes in brain injury rehabilitation.
00:00.567 --> 00:01.532
00:01.533 --> 00:04.632
There are a lot of definitions of what a concussion is.
00:04.633 --> 00:05.766
It's kind of mind-boggling.
00:05.767 --> 00:08.666
It sort of adds to the confusion of what concussion is.
00:08.667 --> 00:11.999
Most definitions will say that if there's loss of consciousness,
00:12.000 --> 00:13.532
it's less than 30 minutes.
00:13.533 --> 00:16.799
Typically, oftentimes, there isn't loss of consciousness,
00:16.800 --> 00:20.632
and symptoms generally, not always, resolve within days to weeks,
00:20.633 --> 00:23.299
sometimes a little bit longer.
00:23.300 --> 00:28.232
00:28.233 --> 00:32.266
So a concussion is a traumatic brain injury,
00:32.267 --> 00:36.266
but it's considered on the milder end of the spectrum continuum.
00:36.267 --> 00:39.766
So if there's loss of consciousness, by definition,
00:39.767 --> 00:43.266
it has to be less than 30 minutes, based on most definitions,
00:43.267 --> 00:47.199
and the symptoms generally resolve within hours, days,
00:47.200 --> 00:49.999
weeks, sometimes a little bit longer.
00:50.000 --> 00:53.366
When there's an injury to the brain, let's say a concussion,
00:53.367 --> 00:56.032
the first thing to realize is the brain is actually very soft.
00:56.033 --> 00:58.532
It has the consistency of formed Jello.
00:58.533 --> 01:01.166
And when your head gets jerked backwards and forwards
01:01.167 --> 01:06.032
and sort of to the side, the brain can actually compress on itself,
01:06.033 --> 01:08.699
stretch, can twist a little bit,
01:08.700 --> 01:12.499
and that compression, that stretching, the twisting,
01:12.500 --> 01:15.332
will actually stretch all of the nerve cells,
01:15.333 --> 01:17.699
or part of the nerve cells called the axons,
01:17.700 --> 01:20.399
and the axons are like telephone wires,
01:20.400 --> 01:23.932
or like wires in a computer network.
01:23.933 --> 01:26.032
If they're stretched, there's going to be a period of time
01:26.033 --> 01:28.166
where they're just not gonna work properly,
01:28.167 --> 01:30.932
and they're not gonna transmit information properly.
01:30.933 --> 01:35.199
And in order for us to do what we would normally do as humans—
01:35.200 --> 01:39.199
think, remember, concentrate, maintain our balance,
01:39.200 --> 01:41.832
have our eyes and our ears coordinate properly
01:41.833 --> 01:44.499
so our balance doesn't go awry—
01:44.500 --> 01:47.232
all of that's gonna be off or it could be off,
01:47.233 --> 01:50.199
and those are the symptoms of concussion,
01:50.200 --> 01:54.499
and it's explained by the stretching of those nerve cells.
01:54.500 --> 01:56.899
Eventually, in the vast majority of cases
01:56.900 --> 02:00.032
after mild traumatic brain injury, things settle down,
02:00.033 --> 02:02.899
and then your symptoms resolve.
02:02.900 --> 02:09.867
Acute mild traumatic brain injury (concussion) in adults. Waltham, MA: UpToDate, 2020. (Accessed on March 31, 2020 at https://www.uptodate.com/contents/acute-mild-traumatic-brain-injury-concussion-in-adults.)
Severe TBI. Atlanta, GA: Centers for Disease Control and Prevention, 2019. (Accessed on March 31, 2020 at https://www.cdc.gov/traumaticbraininjury/severe.html.)
Symptoms of traumatic brain injury (TBI). Atlanta, GA: Centers for Disease Control and Prevention, 2019. (Accessed on March 31, 2020 at https://www.cdc.gov/traumaticbraininjury/symptoms.html.)
Traumatic brain injury & concussion. Atlanta, GA: Centers for Disease Control and Prevention, 2019. (Accessed on March 31, 2020 at https://www.cdc.gov/traumaticbraininjury/index.html.)