TBI/Amnesia

Luno

Luno

OG
Premium Member
Messages
666
Reaction score
51
Points
28
Hey, wondering if any of you have any links to podcasts covering TBI, especially antero/retrograde amnesia, after/during evaluation of suspected concussion. I've seen quite a few of these, so many that we call it the control-alt-delete syndrome... I'm interested in more specifically the etiology of the symptoms. Thanks -luno
 
Are you looking for something that will help you evaluate concussion w/ either form of amnesia or just simply why it happens? If you're looking for why it happens, it's probably due to some diffuse axonal injury. You can't see it on an MRI, but... the damage is there. It has been a while since I've reviewed amnesia in the setting of TBI/Concussion... You might search for management of concussion in athletes... They tend to suffer a disproportionate amount of TBI in the form of concussion... and I've seen (and evaluated) all the grades of concussion up to Grade III in the Cantu or AANS Grade IIIb and the patient regains consciousness in the field. I've been on the response team with patients who've never regained consciousness in the field, but did regain consciousness later, in-hospital.
 
Last edited by a moderator:
I'm comfortable in the field, evaluation concussions, and the associated antero/retro amnesia, I'm more intested in etiology, and instruction points for EMS providers. It's one of those things that I've studied, and has been pushed to the back shelf by my brain, retaining only the "warning" signs.
 
I checked and didn't find much in the way of research in Mild Traumatic Brain Injury, as far as actual etiology is concerned. There's quite a bit of information about the Post Concussion Syndrome, and Grades 1-3 Concussion, but being that these aren't typically managed surgically, there's probably not a whole lot of info as to why/how this actually occurs in the brain.

As I stated before, this probably is due to some kind of mild diffuse axonal injury from the typical coup-countercoup mechanism. In effect, the brain gets bumped around inside the cranial vault. Tissues, when injured, tend to swell, and in the brain, I found an abstract that indicated that there was some localized edema, and it was the glial cells that actually were swollen. This had the effect of pinching off the microvasculature (capillary beds) within the brain, thus reducing the effective perfusion to various areas of the brain.

Either way, it appears that communication between cells is somewhat disrupted, or slowed down, and it's possible that because of this, recall of events can become difficult or impossible as the brain just can't get to those areas responsible for recent memory... or as the injury progresses, short-term memory stops working correctly as that area isn't as well perfused.

In a way, it's almost like an instant "Control-Alt-Delete" but due to minor injury that's difficult to impossible to see on an MRI or CT, the "file structure" where recent events gets converted to longer term memory is temporarily broken and those memories are simply... lost. Eventually, the damage is repaired, and that system begins working again..

That's about how I figure it...

It HAS been a while since I've looked into this...
 
I think I have a base understanding of the physiology of the incident, I guess what I'm looking at is why 7 min reboot, instead of 5 min, or reverse, and is there a corrolation between reboot times and final outcomes. Also agree with the coup/countercoup motion, but being that there isn't necessarily anterograde amnesia, even with a positive LOC, is there a specific area that is affected when there is antero or retro, vs a general LOC? Is there swelling that is caused by hitting one specific area of the skull, or is there a predictive impact area (by the brain within the cranium) that causes the amnesia? I guess that I am interested in this more, because I have had a LOC personally that caused both kinds of amnesia, and lasted over 30 minutes.
 
I suspect that longer LOC times have to do with a greater amount of cerebral disruption, and the greater the disruption, the longer amount of time someone's going to experience the PCS. It's very much possible to have ante or retrograde amnesia with this... However, the exact mechanism why either occurs, I'm not sure, nor exactly which region of the brain is directly affected. Mostly, this is probably due the fact that there really isn't much known about mild TBI, where's there's a LOT more known about moderate/major TBI.

I have heard of Concussion Grades above III... but these patients never regain consciousness in the field, and they have a much more extensive rehab post injury, if they survive... Grade VI results in death, from massive, but diffuse axonal injury. Basically, the brain is shaken so much that axons no longer connect with the dendrites of other neurons. Kind of like what happens when you shake a motherboard so badly that while the components might stay in place, all the electrical connections break and render the system unusable. You won't see this on an MRI, but it would be seen under the microscope (prepared slides) at autopsy.

At least that's my understanding of Concussion type TBI.

Luno said:
I think I have a base understanding of the physiology of the incident, I guess what I'm looking at is why 7 min reboot, instead of 5 min, or reverse, and is there a corrolation between reboot times and final outcomes. Also agree with the coup/countercoup motion, but being that there isn't necessarily anterograde amnesia, even with a positive LOC, is there a specific area that is affected when there is antero or retro, vs a general LOC? Is there swelling that is caused by hitting one specific area of the skull, or is there a predictive impact area (by the brain within the cranium) that causes the amnesia? I guess that I am interested in this more, because I have had a LOC personally that caused both kinds of amnesia, and lasted over 30 minutes.
Click to expand...
 
Function versus/and formation

How much of the affect is a result of the brain's anatomy (formation), or the mind's function?
I had two friends who were in MVA's before shoulder harnesses and airbags. Each had amnesia of the actual accident once they regained consciousness, each was diagnosed (clinically and by xray, this was pre-CT and MRI) as having a mild to moderate stable concussion and sent home. One suddenly had a flashback and regained memory, the other never regained independent recollection, at least not in 20 years.
Go figure.
 
mycrofft said:
How much of the affect is a result of the brain's anatomy (formation), or the mind's function?
I had two friends who were in MVA's before shoulder harnesses and airbags. Each had amnesia of the actual accident once they regained consciousness, each was diagnosed (clinically and by xray, this was pre-CT and MRI) as having a mild to moderate stable concussion and sent home. One suddenly had a flashback and regained memory, the other never regained independent recollection, at least not in 20 years.
Go figure.
Click to expand...
I would suspect that it has to do with how the brain is put together... at the neuronal level. I would be very surprised to learn that your friend that had recollection of impact actually remembers the impact itself. Recollection of the moments immediately up to and right after impact (after regaining consciousness) would be far more common. Depending upon the structures that got shaken around, there easily could be some amnesia to events just prior to impact.

Frankly, I'd suspect that most of the PCS is structural (hardware) rather than psychological (software) in nature.
 
You must log in or register to reply here.
Back
Top