how much does the brain fluid cushion?
 

I'm sorry to open another thread but i am extremely worried, after i became symptoms that only occured in the first days after my concussions happened.

I have scoliosis and twitches of my lumbar spine happen. This causes my head to move very quickly down for like 1 inch(hard to discribe). It normally happens only two times a day, but after it happened about 10-15 times in a short period of time, i am really concerned as i feel that something is wrong. It happened over one week ago and the symptoms did not resolve.

My neuro could not tell me, if the brain hits the skull because of such movements. He said its possibly enough cushioned by the fluid. As the space between the skull and the brain is really small, i rather doubt it. What do you think?

You have asked this question at least twice before. There is no definitive answer. The proper question would be, How much force can the brain tolerate ? Research suggests that the brain can tolerate 20 to 40 G's without any problem. I doubt your twitches even reach a level of 10 G's.

I think your greater risk is the impact your anxiety has on your healing. Anxiety causes the brain's chemistry to get out of balance. This can slow recovery.

I know that I've already asked it Mark. I had a hard time and the anxiety grew especially because no doctor managed to put my mind at ease. All neuros seemed to have no clue.
But your words have a positive effect :)

Do you have a source for what you've written in your last post?

20 G is enormous. I thought that even the slightest impact or twitch could cause the brain to hit the skull, as the fluid has a consistence like water and the space measures only 1-2mm.

Actually, they usually use 60 G's as the threshold for injury. I reduced that number substantially because people do not believe it.

As I said, it is not the fluid space but the amount of impact the brain can tolerate. The sports medicine industry has researched this for football with G sensors mounted inside helmets.

In all my research I have never come across such a figure as that. A source would be appreciated, *edit*. Cheers.

RE. CSF. You have to picture the brain as suspended in the fluid, both fluid and brain fill your skull wholly. It is not open, or with air, so the fluid sloshes around, but is a complete volume.

With most knocks there will remain a cushion, or portion of the CSF volume between brain and skull. With a forceful enough blow, or with great momentum, this cushion is not soft put provides a tense/hard surface. With great enough force/momentum the brain can hit against the skull.

To test this: get a bottle/jar of water. put in a pingpong ball (brain) with a weight attached (brain stem) and fill completely with water (CSF). Have a shake, using diff forces. This will give you a good idea...but remember we are more sophisticated and have evolved this process for protection! :)

However...those twitches? I get them. Though I think of them as tremours, and this is related to my motor issues. It was unnerving but now is kinda annoying and a bit embarrassing. It is not damaging my brain.

A couple of nights ago I smacked my head rather hard againts the rail of my sons bed--went to put something on the desk and stood up in the wrong lace, duh. Symtoms flared, my headache worsened but I did not injure my brain.

Ash,

Do some concussion research related to American football. You will find the information. Until you do, please do not post such negative remarks.

Info-
[60 G's as the threshold for concussion]

https://www.google.com/search?q=60+G...for+concussion

Oh I thanked then clicked. That is ust a link to a google search. A search that shows those measurements are based on wearing a football helmet, and theoretical at that. Does any one have a legitimate and in depth study?
*edit* it cannot be stressed enough that opinions read on boards like these, or in articles should *always* be compared to valid sources or medical professionals/ neuroscientists ect.

*edit*

The Google link has multiple results listed, readers may want to explore them..

The 60 G research is based on a number of sources. The US Air Force did G research on pilots. They can experience very high side to side G forces during quick roll movements of fighter jets. The football research was done looking at the head with G sensors (accelerometers) between the helmet padding and the players head with EEG sensors and recording equipment recording the changes in brain wave form. The in-helmet sensors have recorded 120 G's or more for very small times (milliseconds). The NFL uses 98 G's as the threshold for concussions based on their research. Again, this is 98 G's at the skull, not at the exterior of the helmet.

This research has been going on in the US since the mid 1990's. I could give you a long list of names and research organizations but you would likely just discount them anyway. Here is just one : http://www.purdue.edu/newsroom/relea...0-percent.html Note they have seen 250 G's of force in their research.

What is your objection to the 60 G number ? Do you think it is too high or too low based on your understanding ?

admin edit

So, the facts I've found:
- in contact sport a layer is regularly exposed to strikes to the head/body. This increases chance of c/TBI.
-The articles in that search are more often than not, with players wearing helmets ect which would require a greater force to overcome such protection.
-There are cases of 120g with no concussion.
-There are cases with 20g resulting in concussion.
-Direct force to head is not always the case, rotational and lineal forces ect are very hard to measure and research is being done but results are not concluded.
-there are cases of regular 2g force, from spinning in skating, leading to persistent concussion symptoms
-Newton's 3rd law should always be considered, but is often hard to factor in injury incidences.
-it is possible a slap will cause 100's of g force, briefly to a local area, with no damage
-sustained low g force can cause much damage/death, specially if it is of the same frequency of an organ.
-underlying cardiovascular issues decrease g force tolerance
-g force tolerance can be increased by training or countering if blow is seen coming

In conclusion, it is incorrect to say that a 70-90 g force is required for concussion. At best this is a generalisation. There are simply too many variables. I spent 15 minutes researching.

*admin edit* I have already posted, before this comment, which i think should make clear why this question was asked.

Also, it must be noted that this is clearly a fad subect in the USA at recently. NFL ect is big money, the sport is dangerous and that comes with insurance issues. This will have an effect on the research conducted. In other parts of the world, who do not hae such financial investment, it somewhat a moot point. Folks getting attacked, or involved in car accidents (non sport) ect do not factor in this research.

Fro what I can see the research is also flawed in that it does not account for individualistic variables.

Yes it is important to regulate health concerns in sort, whether contact of racing ect, but this is a narrow view and one which is not entirely applicable to most posters here. Most people are not physics whizzis nor do they happen to have measuring devices at the time of accident. It is all very hypothetical, and can seem dismissive of those who are suffering.

Ash,

You are dead wrong about the US research. Most was done without any involvement of the NFL or NHL. They actually fought against the research. It is the injured community that pushed the research, against the insurance companies and other financial interests. Concussions are not a fad issue. The internet just made it so more people can access information without the financial interests getting in the way. A few researchers were able to get their research in front of enough people to achieve critical mass. Motor vehicle, falls, assaults and other causes have always been an issue here.

The increased popularity of soccer, your football, and Title 9 access to sport for women/girls has brought injured girls into the public sphere. Parents often take a greater interest in the health of their daughters than their sons. Mother's have driven much of the public interest.

The 20 G concussion and the 120 G non-concussion are debatable issues. There has been a world wide struggle to define a concussion and MTBI. The 20 G concussion likely happens to a subject with quite a history of concussions. The 120 G non-concussion is likely somebody who has never suffered a concussion. Some are more tolerant of impacts. But then, as has been stated here many times, If you have seen one brain injury, you have seen ONE brain injury. There are a myriad of mitigating factors and differences. Neck issues, etc. can make a big difference.

As you claimed, the research can be flawed. The 2 G concussion claim could be just as flawed. I'm not saying it was. I read research regularly that is not flawed but limited in what it can address. People take the research and make assumptions based on misunderstanding the limits of the research.

Just as you contest the research, you do not have all of the answers either. This forum is not about exacting concepts. They do not exist regarding these issues. Research is a system of compiling evidence with models that are intended to reduce the errors. Often, they only find errors as they do the data collection. As they eliminate these errors or abstracts, they can become more exacting. But, they can't do that with concussions. So, they use a broad cohort.

There is currently a controversy about how to properly collect the concussion data needed to fully understand concussions. The US Veterans' Administration has spent millions trying to identify concussions vs similar clusters of symptoms that may be due to other causes.

So, there is no perfect answer. All we have is the research being done. Most of life is based on similar concepts. If we live life based on the outlier ideas such as " a concussion from 2 G's" we will be paralyzed. If we use common sense and reasonably moderate our behavior based on what we observe personally, we can hopefully move forward. Fretting about involuntary head jerks in bed is problematic when one can currently not do anything to end those head jerks. Stopping compulsive head jerks or head banging to music is worth the effort.

If you will read my comments, I said, "They usually use 60 G's " and "20 to 40 G's." Somebody who can not tolerate 2 G's would need to stay in bed. Walking can impart 2 G's to the head. I know the physics and have run the numbers. G's relate to acceleration and deceleration. Both are changes in speed over time. A sudden stop against a fixed object can cause high G forces for very small time increments. A jerk of the head does not not have that sudden change. It would be near impossible to achieve 20 G's with a simple head jerk. The muscles are just not strong enough to start and stop in the time and distance needed to reach those levels. The repetitive effect of shaking can cause trauma at lower G forces.

The research says that the brain can often tolerate extremely high G forces for miniscule time periods. It is the G force sustained over time that is most problematic.

But, when a question is asked, the available answer is usually based on research or at least a large amount of anecdotal evidence.

btw, You said "-The articles in that search are more often than not, with players wearing helmets ect which would require a greater force to overcome such protection." You ignored the fact that the research is based on G forces at the surface of the skull, not at the exterior of the helmet. There are accelerometers that are less than 5 mm thick by 10 to 15 mm square that are fitted against the skull with the helmet and padding holding them tight against the skull. They are set to measure G forces in multiple axis. Some use piezoelectric effect to sense movement. These are accelerometers similar to those in an iPhone that sense position.

Happy Birthday for the other day Mark btw - seems like you switched from being 59 to 60 recently right?

*
You have also moved the goalposts, so to speak. From talking about force required to cause concussion, to that of specific contact sport incidences. *

*, ignoring sustained, rotational, cenrefugal forces ect). Even with those who are gifted in this area it would be a very impressive feat; not only to measure the variables but to calculate them. Perhaps as sensory tech advances and quantum computers crack prime numbers we will see an improvement here.

* HITs only measure above 15g and only for 48ms. This has been used to improve protective wear and provide predictive (not certain) values.

As I have said the fact remains that there are little facts. There are observations, trends in data ect but no true answer. It is misleading to claim there is*

This is an interesting link, and yes looking at american football. The whole thing is worth reading but I'll pull a few key lines from the conclusion.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2943536/

"Ultimately, the analysis fell short in identifying a single variable or set of variables that predicted concussion in high school football athletes on a level that can used for diagnostic purposes. The use, therefore, of the Head Impact Telemetry System as an acceptable diagnostic tool is not warranted at this time. The HITS can, and does, provide a clear indication of which individuals necessitate further evaluation following an impact."

Reference:-The Biomechanical Properties of Concussions in High School Football
Steven P. Broglio, PhD,1 Brock Schnebel, MD,2 Jacob J Sosnoff, PhD,3 Sunghoon Shin, MS,3 Xingdong Feng, PhD,4 Xuming He, PhD,5 and Jerrad Zimmerman, MD6

Yea, I hit the big six-o early in January. Boy, I feel old.

We are re opening this thread at this time..please stay on topic with replies to OP..
Thank you

I researched as well, and found the following informations:

A fall into a chair creates about 10 g and is sufficient to cause a concussion.

Sneezing and coughing, like we all do everyday, creates about 3 g.

I also saw the research results about nfl players. They said that helmet collissions, which create about 50-60g can cause concussions. But the helmet acts like a second skull, providing additional protection to the head. So this number can probably not be taken for impacts whithout helmets.

(I cannot add links as my number of posts is less than 10)

My second concussion was caused by a fast tennis ball that hit me straight on the head.
According to calculation in a physics forum, a tennisball served at 200km/h creates a force of 3g(the same as sneezing). I don't understand it. How can this tennis ball cause a concussion, when it has the same force on the body as a simple sneeze?

Any idea what the g force might be in a head on collision? Say, at about 50 miles/hr.

:confused:

Just my humble opinion here, but there are far too many variables to be answering these types of questions.

i.e. were you wearing a seatbelt.
Was there an airbag deployed.
What side of the vehicle was hit.
How heavy was the other vehicle.

etc.

Tennis ball. I know a sneeze can be powerful and I know that sneezing can cause people to herniate discs, but again the problem with asking those types of questions is that there is no simple answer.

There are too many variables.

How thick is your skull?
How inflated was the ball?
What side of the head or face or forehead or neck did it hit?
Did you jerk your neck back really fast?
etc.

There is a book called
Concussive Brain Trauma -
Neurobehavioral Impairment & Maladaptation
By: Rolland S. Parker

it might explain some of the more technical and highly variable physics relating to impact.

You can often use specific keywords and search some advertised books online.

I think you are misunderstanding the information you have found.

First. Football concussion research looks at the G forces acting on the skull at the surface of the skin, not the forces acting on the surface of the helmet.

The fall into a chair causing 10 G's sounds very high. If the chair is rigid, and one lands with the back arched (straight vertebral column), and there is minimal absorption through the back side, the G forces could be that high as they are transmitted up the spine. But, a cushioned chair and/or a normally curved back will greatly reduce these forces.

The tennis ball number is also misleading. Is this 3 G's acting on the tennis ball or 3 G's acting on the skull. The fact that a tennis ball distorts means the G force is reduced.

*admin edit*

Regarding sneezing, there is a whiplash effect causing G forces plus a pneumatic pressure in the sinuses.
Here is a good but complex explanation of calculating G forces. http://www.decodedscience.com/mythbu...alling/26999/2

Regarding the head-on vehicle collision. There are far too many variables to even begin to answer that question without seeing the damage to the vehicles (distortion) and movement of the vehicles after contact and making assumptions of occupant movement inside the vehicle. Even the insurance companies do not often try to make these calculations with highly trained accident reconstruction specialists.

When G forces are measured, there are 3 key factors. Speed before collision, speed after collision and the amount of time for that change in speed. The change in speed over time is either acceleration or deceleration and can be converted to G forces. If there is a complete stop, then deflection can be used in place of the time for that change in speed.

That tennis ball is traveling at 55555 mm/sec. It would likely deflect by 12 mms or more. But, if the skull it hits moves back 6 inches (150 mms) during the contact, that movement is part of the deflection. So, the deflection would be 162 mms. The formula for G force is V1 squared minus V2 squared divided by 2 times distortion divided by acceleration of gravity. So, 55555 squared minus 0 squared divided by 324 divided by 9800. That means the tennis ball experienced 972 G's. But the head did not experience the same G force since it started at 0 velocity and ended at X velocity and moved 6 inches (150 mms) during contact with the ball. That calculation is far more complex. This is where the mass of each object would be needed to calculate the G force to determine velocity X. Even so, assumptions would need to be made.

So, hopefully, you see that it is extremely difficult to calculate these forces.

The tennis ball hit me on the forehead, while i was standing at the net. As far as i can remember, my head went back just about one inch(the ball weighs only 58 gramms).

I see how difficult it is to calculate the g's. But i think it is quite interessting to figure out how much is actually necessary to cause a concussion(for instance, everybody around me told me that a tennisball has not the enough force to cause TBI, but in fact it has)

When we say for instance that 10 g's are necessary, does this mean that the brain hits the skull only when a force of 10 g or more is reached or does it hit the skull also on lower g's, whithout resulting in a concussion? The question is interessting, because sneezing or twitching makes me feel dizzy for a while - is that because the brain touches the skull?

(Here is the link which i wanted to add in my last post www.braininjury.com/injured.shtml )

And here i found the tennis ball calculation:

http://tt.tennis-warehouse.com/showthread.php?t=357202

That tennis ball calculation is wrong, He forgot to square the 55.55 m/sec/sec. Plus, he does not account for the time the racket spends pushing the ball in a powering through stroke. Others suggest the ball was in contact with the racket for 48 cms. As he said, he did not stay at a Holiday Inn Express nor is he a physics expert. If the ball was in contact for only a short distance, the 2200 G's would be the answer. At 48 cms of contact with the racket, the G's would be 320.

The ball that hit you was not going 200 km/hr (55 m/sec). A common tennis serve is 34 m/sec as the ball leaves the racket. By the time it crosses the net, it has lost a lot of speed, maybe to 25 m/sec.

At 58 grams, the tennis ball does not have much effect on a 5000 gram human head attached to a heavier body. According to my calculations, a 5000 gram head would move only about 5 inches when struck by 58 grams at 25 m/sec. The G's of that hit would be about 50 or maybe a bit more. It would move less if there was an effort to limit any movement. In that case, the G force would be higher. Sounds like enough G's for a concussion.

The numbers in the braininjury.com web site are not supported by either research or common physics. It would take quite a plop to get 10 G's. It would take a 20 inch fall with only 2 inches of cushion distortion to get 10 G's. I don't know of many butts that are 20 inches higher than the seat of an easy chair with only 2 inches of cushion distortion. Mine distorts about 4 inches. This site is an attorney's web site with a lot of 'selling to the jury.'

There is one more thing that bothers me. I've read that some people got concussions from hitting there head (very) lightly against a hard, non moving surface(wall, table). It happens unfortunately from time to time to probably everyone(you can't be cautios enough)

Back to our g calculations, how can such a light bump ever cause a concussion? I mean there is not enough acceleration of the brain that could reach the required g force, even though the deceleration is of course higher.

Those things you read are likely not accurate. A light touch against a hard object or wall would not cause a concussion. It may cause an anxiety response. A very sensitive brain may sense a slight 'dinger.'

You guys need to think more about the heads structure in your attempts at calculations and ponderings.

Different substances absorb force in different manners, as does structure diffuse. IE Skin and bone behave very differently under force. And then there are different strengths and weaknesses in the scull. Then an understanding of where nerves/blood vessels lay. Where the impact is will serve to antagonise/mitigate the blow.

If you have a hard tap to the right place on the head it is possible, as the flesh/skin would becomes inflamed and starts to heal, you may have a few burst blood vessels and if this is over a nerve the inflamation could cause the signals to get muddled for a few weeks (or much longer if the actual nerve is damaged, with greater force).

Ash,

We are not discussing surface or skin confusions. Yes, they can be painful but do not relate to the concussion forces that we are discussing.

Mark, even you said in one of your older posts that light hits can cause a concussion.

http://neurotalk.psychcentral.com/thread82429.html

Nonetheless this is not the only source I found. I googled for a couple of minutes and saw quite a number of posts, where people experience concussion symptoms after a light bump(even without prior head injuries)

I don't excactly know what you mean with 'dinger'

The case in that thread was jumping and hitting the head into the ceiling. That is not a very light hit. A dinger would be the same as what researchers call a sub-concussive impact. There is an awareness of bumping the head or suffering an impact but no concussion symptoms, either immediately or later.

S is that very small distance. It is the deflection distance or thickness of the cushioning. It is very difficult to determine but the starting velocity is also difficult to determine. A falling object has a known velocity based on the acceleration of gravity but a horizontally moving object requires some sort of metering of the horizontal speed. A slow walking speed of 3 mph is 134 cm/sec. 134 squared is 17956. If there is 1 mm (.1 cm) deflection, then you would divide the 17956 by .2 divided by 980 cm/sec/sec to get 91.6 G's. If the deflection was 1 cm, then you would divide that by 2 (2 times deflection of 1 cm) and the G force would be 9.16 G's. If the deflection was .25 cm then the G force would be 36.32 G's.

If the 3 mph speed (134 cm/s) was not directly at the wall, you would need to calculate the velocity vector perpendicular to the wall. At 45 degrees, the speed perpendicular to the wall would be 2.1 mph (94 cm/s). At 1 mm (.1 cm) deflection, then, 8798 divided by .2 divided by 980 is 44.9 G's. You need to make sure everything is in the same units: meters, centimeters or millimeters.

At the 1/2 mph speed (.13734 m/s) you used with 1 mm deflection, the G force would be 0.96 G's. That is like gently lying down on a hard surface. Your head at rest would be 1 G.

The deflection is the amount of distance the glass door or wall moved combined with the flexing of your skull. If the total deflection was .5 mms, then the G force would be 1.96 G's. If the deflection was .25 mms, the G force would be 3.85 G's.

If you could measure it, you would find that a glass pane has quite a bit of flex. Just watch the reflection off a glass pane during a wind storm. The pane will bow in and out. Plus, there would be some movement in the glass frame in the door track. Even a wall has flex.

I would think that CSF would be considered in the deflection.

As I said in the other thread, any sound is the result of deflection. A brick wall will not make a sound but the skull will make a thud as it deflects.

Hi Katharsis,

I'm just wondering if discussing this actually helps calm your anxiety or does it make it worse and you worry more?

Sometimes it is hard to let go, but all this calculating and trying to figure out technical possibilities & scenarios...... that alone is a big strain on the brain when you should be letting it rest...:grouphug:

Thanks for your honest answer.

I was asking because I too have anxiety issues and that was long before head injuries. Born that way ;)

I love to learn and figure things out and sometimes working things out will help me but other times it will make me more anxious because it can almost feel as if it's feeding my anxiety. That is why I asked the question.

It's good you're going to see a professional to help you with your anxiety.

All they have to do is give me the parameters and I will do the calculation. One of the common ways to overcome anxieties is to demonstrate the truth that overcomes the irrational thoughts.

I and an number of others use our Christian faith to reduce our anxieties. It may be a continuing battle but it is effective. Anybody can PM me for how I specifically use my faith to overcome anxiety. Discussing faith in the main forum has not always been well received.

Difficult question.

After the concussion I had around 10 years ago, my anxiety became much worse. I have residual vertigo that has become much better now, but it was quite bad for a number of years. That really was the thing that made me worse because I became afraid of falling again.

I watched every step and feared so much going through it all again. The fact is that it was my fear/anxiety that made me disabled more than the concussion did. I stopped living my life for a while there. I was afraid to drive and afraid to go to shopping centres with slippery floors.

I was afraid of wet concrete. You name it and I was afraid.
IMHO, they were not irrational fears. They are rational fears because a. I had fallen and b. I didn't want it to happen again.

Because I've always had this background anxiety disorder (mostly I just work around it) I was having panic attacks all the time. Not good!

I have in the past had treatment for anxiety and obsessive compulsive issues but I refuse to ever take medication again so I've tried more alternative routes. I use supplements and I practice relaxation techniques and attempt to meditate regularly although that is difficult with all the background chatter going on in my brain sometimes. ;) I don't relax enough mentally but I'm much better than I was.

If anxiety reaches a point in your life when it is affecting your daily life, then it's really important to seek help dealing with it. There are many ways doctors treat anxiety and it doesn't just mean taking medications. Cognitive Behaviour Therapy can help us recognize the patterns we have learned with our thought processes and with guidance, they can be changed.

It's all very individual.

p.s. I think you wrote in your first post that you were at university.
Does your University offer any help for students who are facing health issues such as this? That is worth investigating as it may help you keep on track with your studies and at the same time you will have support and maybe accommodations set in place in your learning environment.

Now that is a big topic for discussion!!
Lots of folks have that very same issue.

Simple non medicated ways to mellow out / relax for best sleep..

This may sound silly but have you ever watched Indian head massage or hair brushing /ASMR videos on you tube?
There are other relaxing videos that you can find - like waves, rivers, soft music.
Some are specifically to help you fall asleep and sleep well..