Understanding the Risks of Second Impact Syndrome in Youth Concussions

A male, 173 cm, 69 kg, faints, falls backwards, his fall is stopped a bit because he falls with his left arm against a cupboard in the bathroom, this happens when he is about 45 degrees with his body compared to the ground, the bathroom has tiles but there is a little flimsy mat to stand on.

What is the g force approximately he hit his head with on the ground?

Thank you so much

Welcome to PF.

QImpact said:

A male, 173 cm, 69 kg, faints, falls backwards, his fall is stopped a bit because he falls with his left arm against a cupboard in the bathroom, this happens when he is about 45 degrees with his body compared to the ground, the bathroom has tiles but there is a little flimsy mat to stand on.

What is the g force approximately he hit his head with on the ground?

Thank you so much

This seems oddly specific. Is it for an accident investigation and reconstruction? Why are you asking this?

berkeman said:

Welcome to PF.This seems oddly specific. Is it for an accident investigation and reconstruction? Why are you asking this?

Thank you. Well it happened to me and got me curious. And i dont know about physics, so that s why i ask here :)

I hope you recovered okay. What were your injuries?

berkeman said:

I hope you recovered okay. What were your injuries?

Im doing okay. I did feel a little bit of headache, but nothing much. It could have also been caused by stress. (It s the second time in 6 months i passed out, so it gave me a bit of a scare, also because this was the back of the head and last time i felt face forward)

If you get hit on the head and pass out, then it s clear u have a concussion. Then you will have severe symptoms like nausea, real headache etc.

I passed out and THEN hit my head. So i wondered how hard the hit was.

People always say in this case : mild concussion. But is it? Could this be a concussion?

They say a concussion happens with about 60-100 g. That s why i wonder how much force my head hit the ground with.

QImpact said:

I passed out and THEN hit my head.

Do you have any idea why you passed out? Have you talked with a doctor about these syncope events (your passing out). Were paramedics called to help you after you were injured?

QImpact said:

People always say in this case : mild concussion. But is it? Could this be a concussion?

We cannot diagnose a concussion over the Internet. I might be able to do that in person but that does not help us here.

QImpact said:

They say a concussion happens with about 60-100 g.

Can you post a link to where you read this? Thanks.

berkeman said:

Do you have any idea why you passed out? Have you talked with a doctor about these syncope events (your passing out). Were paramedics called to help you after you were injured?We cannot diagnose a concussion over the Internet. I might be able to do that in person but that does not help us here.Can you post a link to where you read this? Thanks.

I think it was a combination of flu and being tired. Last time i also was sick and tired.

https://www.drheisig.com/blog/how-m...you need to,and schedule a consultation below.

A mild concussion cant be diagnosed conclusively (although pet scans can show alterations of brain function). It s not like i want a diagnosis, but just wonder how much g force it was

It would help if you could also answer my other queries above. Thanks.

berkeman said:

Have you talked with a doctor about these syncope events (your passing out). Were paramedics called to help you after you were injured?

On your impact g acceleration (not force) question, a ballpark is if you go from ##-1\frac{m}{s}## velocity (that's in the downward direction) to ##+1\frac{m}{s}## in say ##100ms##, that takes on average about ##2\frac{m}{s}\frac{1}{0.1s} = 20\frac{m}{s^2}## of acceleration. Since ##1g = 9.8\frac{m}{s^2}## that gives a ballpark of ##2g## of acceleration.

If the time of the "bounce" of the head is much shorter (like it could be on bare tile) or if the velocities are higher, that gives higher "g" accelerations. If the bounce is off of a floormat instead of bare tile, that gives a lower acceleration.

berkeman said:

It would help if you could also answer my other queries above. Thanks. On your impact g acceleration (not force) question, a ballpark is if you go from ##-1\frac{m}{s}## velocity (that's in the downward direction) to ##+1\frac{m}{s}## in say ##100ms##, that takes on average about ##2\frac{m}{s}\frac{1}{0.1s} = 20\frac{m}{s^2}## of acceleration. Since ##1g = 9.8\frac{m}{s^2}## that gives a ballpark of ##2g## of acceleration.

If the time of the "bounce" of the head is much shorter (like it could be on bare tile) or if the velocities are higher, that gives higher "g" accelerations. If the bounce is off of a floormat instead of bare tile, that gives a lower acceleration.

Oops i forgot that question

They did an ecg (heart), checked blood sugar and everything was ok.it was probably vasovagal syncope because of the combination of flu and being tired

Well 2g doesnt seem much :p

If the medics did those checks soon after they got to your home, most likely they did some simple concussion tests on you and they were negative. Did they give you a list of things to watch for that night (it's a common list for head injury patients)?

I had a skateboard crash patient one time (alcohol was involved) who hit their head on concrete after falling straight off the back of their board (no helmet). They did indeed end up with a concussion, but we were able to diagnose it fairly easily on-scene and convince him (and his family) that he needed to be transported by ambulance for observation and more tests (like for bleeds in the brain).

Glad again that you got checked out and were okay.

berkeman said:

If the medics did those checks soon after they got to your home, most likely they did some simple concussion tests on you and they were negative. Did they give you a list of things to watch for that night (it's a common list for head injury patients)?

I had a skateboard crash patient one time (alcohol was involved) who hit their head on concrete after falling straight off the back of their board (no helmet). They did indeed end up with a concussion, but we were able to diagnose it fairly easily on-scene and convince him (and his family) that he needed to be transported by ambulance for observation and more tests (like for bleeds in the brain).

Glad again that you got checked out and were okay.

Also my general practitioner saw me and he said: you act like always, you are talking coherently, so jo need to suspect contusion

QImpact said:

you act like always, you are talking coherently, so jo need to suspect contusion concussion

Fixed that for you.

(I'm pretty sure you had a bruise/contusion, even if it was hidden by your hair)

berkeman said:

Fixed that for you.

(I'm pretty sure you had a bruise/contusion, even if it was hidden by your hair)

Oops i mean there is a brain concussion and a brain contusion, right? And the second one is dangerous and you cant sleep without supervision right?

Well, a brain contusion is a concussion, as far as I know. Maybe there is some subtle difference that I'm not aware of.

And yes, one of the things on the head injury list is to have a family member wake you up every couple hours to be sure you are reasonably coherent (modulo the fact that you were just awakened in the middle of the night), and not weak or nauseous/etc.

I once had a young basketball player who fell on an outside court during practice and hit his head. He was mostly fine at the time, but luckily his dad (my co-coach) had a medical background too, and checked him multiple times that night. Turned out they went to the emergency room early in the morning due to the son's symptoms, and sure enough it was a subdural hematoma that the son had to get treated for.

I'll move this thread to the Medical forum now, since that fits better than the original Other Physics Topics forum.

berkeman said:

Well, a brain contusion is a concussion, as far as I know. Maybe there is some subtle difference that I'm not aware of.

And yes, one of the things on the head injury list is to have a family member wake you up every couple of hours to be sure you are reasonably coherent (modulo the fact that you were just awakened in the middle of the night), and not weak or nauseous/etc.

I once had a young basketball player who fell on an outside court during practice and hit his head. He was mostly fine at the time, but luckily his dad (my co-coach) had a medical background too, and checked him multiple times that night. Turned out they went to the emergency room early in the morning due to the son's symptoms, and sure enough it was a subdural hematoma that the son had to get treated for.

But how is that possible? If you get a concussion woth 60g and falling is about 2g as you calculated, then how can you get a concussion?

QImpact said:

But how is that possible? If you get a concussion woth 60g and falling is about 2g as you calculated, then how can you get a concussion?

Higher fall speeds, more of a whip action on the head/neck at the bounce, hard surface with shorter bounce time, etc.

Plus, the reference you supplied is not a valid medical reference. You may want to look around a bit more to see what the range of g values are for concussion studies.

berkeman said:

Higher fall speeds, more of a whip action on the head/neck at the bounce, hard surface with shorter bounce time, etc.

Plus, the reference you supplied is not a valid medical reference. You may want to look around a bit more to see what the range of g values are for concussion studies.

We had a similar thread a couple of Years ago about guy who hit his head on his car door and wanted to confirm the g forces.

I went for F=ma others went for KE

It is probably worth pointing out that it's not really the g-forces that cause damage. It's the difference in force across your noggin. If everything accelerated uniformly, there would be no force between one part of your head and another - so no damage.

So you're not even asking for the relevant number. Unfortunately, the right number is harder to calculate, harder to measure, and harder to compare with similar numbers.

This from the British Medical Journal: https://bmjopen.bmj.com/content/4/5/e005078

Referencing football players and helmets:
"The 50% and 75% likelihood of concussion values for resultant linear head acceleration in this study were 65.1 and 88.5 g, respectively."

Above found with:
https://www.google.com/search?hl=en...=minimum+acceleration+for+cerebral+concussion

Cheers,
Tom

And the simple case of free fall under gravity through distance ##z_{fall}## followed by stopping over a distance ##z_{acc}## the size of the stopping acceleration is at minimum $$a=\frac {z_{fall}} {z_{acc}} ~g$$

My father fell and hit his head 2x 2 years ago.

The first time, he blacked out for 10 minutes. We never called his primary or urgent care doctors, b/c they'd already told us before that if he hits his head in a fall, he should go to E.R. (he's on blood thinners and could bleed to death). Surprisingly, my father's 1st fall with LOC resulted in a clean CT scan of the head. His PCP, however, warned very seriously to monitor him for months afterwards. A delayed brain bleed can happen. This is what former President Ronald Reagan had happen to him we were told. Even if symptoms aren't very bad at first, you have to be vigilant for several months before you're in the clear.

My dad had some delayed concussion symptoms from the 1st head fall.

Several months later, he fell and hit his head again (from a mere standing position of less than 6 feet) and had no LOC this time. However, he did express pain immediately and at the hospital they found a subarachnoid hemorrhage and subdural hematoma from CT. Essentially, he was bleeding from his brain and blood had collected and pooled inside of his cranium. If it is a lot and stays there long enough, it can put pressure on the brain and cause brain damage or even death. He was put into ICU for trauma protocol and they had to reverse his blood thinner with KCentra, infuse him with a separate blood clotting agent, and monitor him. The size of his SDH was less than 10mm, so he was not acute. They chose not to do surgery and he was very lucky. Had the SDH been just a slight bit bigger, it could have required surgery to drain the blood and relieve brain pressure. But, my dad was not the same for a long time. I honestly can't tell if he's fully recovered or not. There was likely some brain damage that's permanent. For sure, he went through months of not remembering how to do basic stuff and having intense physical, occupational, and speech therapy.

With any head injury from a fall, if you've had LOC, I personally think that's an automatic E.R. trip. I spoke to an E.R. doctor who said there is an unspecified amount of time that a person with a brain bleed may not realize it. By the time it presents with noticeable symptoms, that person may be in bad shape and even dead. In addition to asymptomatic bleeds, you also have delayed bleeds I mentioned earlier. I would look up symptoms of brain bleed online to be sure you're not having signs (of current or future/delayed bleed).

Time to getting help can be critical sometimes. In my dad's case, he got to the hospital in decent time and they infused him with something to help his blood clot (they'll do a PT-INR test to see how fast your blood clots and probably other general blood work to see if you're missing anything that is related to clotting and infuse you with any missing agents if you've got a bleed). If one waits too long and really does have an injury, it could lead to brain damage and bad long-term outcomes.

Also, OP, if you're young (like maybe under 21), you could be at VERY serious risk for second impact syndrome. It's when you have two concussions within a short period of time. The brain may not have healed from the first and when it gets hurt again, the second injury (even if it's minor and not as bad as the first) can lead to very serious brain issues.

I would look up second impact syndrome or double concussion syndrome. It tends to have much harsher consequences for those who are younger (if I remember correctly all or almost all cases have been with those with still developing brains in the literature).