What is the reason for stress intolerance following a TBI?
 

I'm now dealing with PCS, and I noticed that with good sleep and very low stress levels, my symptoms become much milder and I just feel OK.

But a little bit of stress, I noticed, will cause my symptoms to return and make my life harder for a few days (just a little bit of stress messes me up, sometimes for a few days). Without stress, I'm feeling 80%-90% of what I was before my mTBI (which was 2 months ago). Although that sounds good, if you put me in a slightly stressful situation for a minute or two, I'll feel 20%-30% of what I was before my mTBI, and I'll most likely stay with that feeling for a few days. And by stress, I don't mean something necessarily extreme - it could just be an argument with someone.

Is it known exactly why the concussed brain has intolerance for stress especially early in the recovery process? I mean, is there an explanation for what parts of the brain that are responsible for stress tolerance are functioniong more weakly after a concussion?

By the way, I'm learning neuroscience, pharmacology and biology at my free time, so I have some understanding in these areas.
As a part of my learning, I would like to understand the causes to the extreme sensitivity of the concussed brain to stressful situations.

Does anybody here know and can please give a detailed explanation about these stress tolerance mechanisms?

Thanks,
-ProAgonist

From what I understand, stress intolerance is due to a failure of part of the brain that filters out excessive stimuli so that the remaining stimuli is within the brain's ability to process. A large amount of brain processing energy is spent filtering out this stimuli. When this failure happens, the rest of the brain is overloaded with excessive stimuli. This is made even worse with PCS because much of the brain is already struggling to function.

There are likely other issues at play but this is likely the most problematic issue.

Thank you for your reply, Mark.

You said that from what you understand, there's a part of the brain that has difficulties filtering out excessive stimuli in PCS sufferers.

But what I don't understand is, how do all PCS sufferers get damage to this part? I mean, brain injuries are very different among different individuals. Some people may get an impact on the right side of the head, while others may get on the left side, back of the head or the upper part of the head.

So how does this part get damaged in all people who get TBIs, independently of the location of the trauma?

Also, why do most parts that get damaged in the brain make a good recovery, but this part doesn't recover very well? And is it not known yet exactly what is that part of the brain responsible for stress filtering or where it is located in the brain?

I would like to expand on this topic--

Inhibitory neurons use GABA primarily and are responsible for reducing over excitation. It is thought that ADD/ADHD is a disorder of poor inhibitory control.

http://www.medicaldaily.com/brains-n...healthy-289338

More on inhibition:
http://www.ncbi.nlm.nih.gov/pubmed/10924667

For learning about the nervous system this is a good site.
It was made for kids, but I think it is a good learning tool for everyone:
http://faculty.washington.edu/chudler/neurok.html

example of inhibitory neurons and pain:
https://faculty.washington.edu/chudler/pain.html

The Washington site is huge... but filled with useful information to help you understand your nervous system.

Thank you for your reply, mrsD.

The stress intolerance I was talking about is related to mTBI/TBI, not ADHD.

I do know that the GABA system dysfunctions in ADHD, although the major problem is the Dopamine metabolism - Dopamine is metabolised too fast and many of it cannot reach the receptors and activate them because of this problem.

As you have said, the GABA system doesn't work well enough in ADHD and this creates a problem with over-excitation, but it's not only GABA. Other inhibitory systems, such as the endocannabinoid system and the opioid system are also thought to be somewhat related to poor inhibition seen in ADHD patients.

The opioid and endocannabinoid systems are similar in their roles, and they are both integral parts of the reward system, together with GABA (dopamine/norepinephrine are related to "wanting" - they are important for reward prediction and motivation but are not part of the reward system). Unfortunatenly, both systems, motivation and reward show some dysfunctioning in ADHD patients (although the low dopamine is the biggest problem of ADHD).

It's important to notice that stress hormones/neurotransmitters such as Dopamine and Norepinephrine are important to self control, even though they are stimulating (too high or too low levels of dopamine will cause hyperactivity, for example, and normal levels are needed for self control).

But back to the main point - I have suffered stress tolerance problems since my mTBI and posted this here since I wanted to know what parts of the brain are exactly responsible for low stress tolerance after suffering a concussion. Also, I think that everyone suffers a cognitive decline in higher stress levels - it's just that it's more severe in PCS patients than in most people.

What I am reading in Science News articles lately is that there are hubs of neurons all thru the brain scattered, that move impluses all over. They are not "organs" like the hippocampus, etc, but little clusters of neurons.

example:
http://www.sciencedaily.com/releases...0929154714.htm

If you search "hubs of neurons in the brain" you'll find more.

Brain science is still very crude...you might not find definitive answers yet.

This can make matters much more complex in treating brain problems (such as traumatic brain injuries or mental disorders),
but this can also allow brain researches to understand better how to help the brain recover from injuries.

It especially complicates the understanding of concussions, but I hope it'll also lead to a better understanding and better treatment of TBIs in the future.

Here is the hubs in the brain article I found for you, ProAgonist:

https://www.sciencenews.org/article/...study-suggests

Illustrations are helpful for this tough concept.

and nearby in this search:
ADHD
https://www.sciencenews.org/article/...-symptoms-fade

Our family has subscribed to this wonderful magazine since the 1960's.... so you might find it interesting too.

Pro,

Not every concussion sufferer has the same stress intolerance. For some, they are just intolerant of cognitive load. Others, visual stimulation or audio stimulation. Even others, tactile stimulation.

My neuro explained it this way. Sensory information is received into the brain. It needs to be filtered and directed to the proper processing areas. The term he used was 'gating,' as in gates open and close to control the flow of information. He could see how this flow was happening by observing the wave forms in a qEEG. In my case, he could see the amount of sensory information that was being received by the brain and then compare it to the amount of information that was being sent to the various parts of the brain for processing. He responded with "You hear everything. How do you handle that ?" He had not been informed that I had horrible struggles with audio over-stimulation.

If I remember it correctly, this gating happens in the area of the the pons and corpus callosum. If you look at the anatomy of the brain. This area has a different mechanical structure. The pons is connected to the brain stem that is anchored in the spinal column. The corpus callosum is between the two hemispheres. This creates shear points where axons have greater risk to physical stresses from all directions. Forces on the right hemisphere are different than the forces on the left hemisphere with the strain concentrated at the connection between the two. Just as the neck is traumatized when the head moves with more force than the body can follow. So, as these communication pathways between the right and left and front and back are strained, the information that needs to travel along these pathways become disrupted.

Add to this the chemical strains on the brain as it tries to rebalance itself, and you have a problem. Since sensory stimuli processing is such a huge percentage of the total brain processing load, this becomes a big problem.

Some of this chemical strain is due to the strain to the vascular and glymph system that needs to drain away the waste products. The brain's 'sewer' system gets backed up.

The injured brain gets stuck in a Catch-22. It is overloaded with processing demand and the resulting chemical waste reducing its capability thus increasing the waste output in a clogged system.

Great info Mark and well laid out. I had a BAEP test down and indeed my left pontine region was abnormal and in theory causing the overstimulation unique to my injury. Different types of lighting in a building and ambient noise or background conversations can cause my brain to 'shut down'.

Pro, when this happens I look at the floor or a stable object and try to only focus on that - almost as if meditating and looking at a candle- that seems to help me deal with the overstim and regain control of my ability to handle sensory input.

My OT also mentioned that proprioception is huge in maintaining control- stand with feet shoulder width apart- get grounded - and if you need touch a wall or lean against it so your body feels 'safe' and doesn't have to find spatial awareness and can focus on receiving information from your situation.

Overstim sucks! And like you I just have to relax and do nothing for a bit until it goes away. Good news is after incorporating mandatory brain breaks every 2 hours as a prevention measure against overstim- I've noticed improvement. The brain can heal!!

Good luck!