You know even more on the topic than I thought you did. I wouldn't mind reading a summary of how you think you ended up having PCS, what you would advise doing or not doing to avoid being in that situation of having PCS, or maybe some interesting facts you came across during your research.
It's an important topic and a lot of people still lack proper education on the topic. People like you can massively help by educating others.
There's a lot to unpack, but I can try. I've been thinking about doing a writeup, but I have a few other obligations coming up so maybe in a little while. It's a difficult field because there are no respectable clinical guidelines, and a lot is not known about concussions and brain damage still. First thing is to clarify what a concussion is.
Part 1
Mechanism and pathophysiology of a concussion:
A concussion is a mild traumatic brain injury as a result of trauma either directly to the head, or indirectly to other parts of the body, causing a rapid acceleration and deceleration of the brain. As soon as that happens, it sets off a pathophysiological process in the brain and an influx of glutamate and calcium, amongst others, which starts something called the neurometabolic cascade. This creates systemic changes in the brain including a release of inflammatory cytokines, disruption of the blood-brain-barrier and metabolic energy deficits. Concurrently, as mentioned in the vid in the OP, the initial trauma can cause biomechanical stretching and tearing of axons, which are nerve cells, and damage the white brain matter, which is the fatty matter covering those cells. This leads to slower synapse speed, aka, slower brain functions. All these things are thought to be behind the symptoms of a concussion which includes headaches, dizzyness, foggy brain, impaired cognition, nausea, anxiety, so on. This metabolic cascade usually lasts about 10 days, and after 14 days up to 90% of people suffering from a concussion are symptom free. However, 10-15% get prolonged symptoms, even after the acute disruptions in brain metabolism has subsided. No one knows exactly why that is.
Contrary to popular belief, you do not have to lose consciousness to sustain a concussion. In fact, 90% of concussions happen WITHOUT the loss of consciousness. The tricky part is, that regular CT scans and MRIs can't tell you anything, and at this time, there are no standardises biomarkers for detecting a concussion. Certain unique MRIs, SPECT scans and even EEGs can shows signs of damage, but they are not included in general practice. You are diagnosed by your symptoms, which makes it harder to define as a condition. Future reliable biomarkers are needed, and being researched.
Whiplash, vestibular and occular (eyes) dysfunction are often accompanied by a concussion, and are thought to be part of why some people have prolonged symptoms. It is pretty well established in the literature. However, newer research shows that dysautonomia, or rather, dysfuntion of the autonomic nervous system after a concussion can be a major factor in why some people experience prolonged or sustained symptoms. That is what our project sought out to investigate. Funny enough, while we were writing it, a review which was the first of its kind showed clear evidence between concussions and dysautonomia (
https://content.iospress.com/articles/neurorehabilitation/nre172298). BTW, I have over a hundred citations which were used in our project, but I wont go through them here.
The aforementoned neurometabolic cascade effects the limbic system of the brain, particularly the amygdala, which is basicly the fear center of the brain. That could explain why the rate of anxiety and depression after a concussion is much higher than in the general population. Equally importantly, the same cascade also effects the autonomic nervous sytem. That, and damage to the cranial nerves as a result of the whiplash often accompanied during the trauma might be why this happens. One of the cranial nerves, the vagus nerve, serves as the main branch to the so called parasympathetic nervous system, which is the "rest and digest" part of the nervous system that makes you relax. This relaxation can be inhibited after a concussion. The autonomic nervous sytem is also responsible for hormonal homeostatis (balance) in the body and works together with several brain regions to create this balance. This can be "out of whack" after a concussion.
That is a VERY cursory look at the pathology behind a concussion, and PCS. Again, no one knows exactly why person A keeps having symptoms, but person B doesn't. As Reys said, it's very much an individual thing. Like all conditions really.