It is estimated that 1 to 3 million have a concussion a year. It is estimated that 0.9% of those will have symptoms beyond a year:
Postconcussion syndrome after mild traumatic brain injury in Western Greece. - PubMed - NCBI
sorry to tired to research other articles.

Assuming that the large majority of PCS are resolved after 3 years (in the 4th year) and assuming that the average yearly number of concussions are 2 million (and assuming no repeat concussions for individuals) I get an estimate of the number of people currently dealing with prolonged PCS in the United States: 54000
This amounts to 0.02% of the population. This means this is a rare disease.

I wonder, how come there aren't many international patients on this website? where do these people go? Usually on other health related forums I find many patients living overseas.

I am dealing with 3 rare syndromes. How many get the privilege. A pat on the back....

How do you come up with your assumptions ?
"Assuming that the large majority of PCS are resolved after 3 years (in the 4th year) and assuming that the average yearly number of concussions are 2 million (and assuming no repeat concussions for individuals) I get an estimate of the number of people currently dealing with prolonged PCS in the United States: 54000
This amounts to 0.02% of the population. This means this is a rare disease. "

What I've read is 15% of concussions have symptoms past 6 weeks. These are the classic definition of PCS. The average annual number of concussions is just those that show up in ER's or Urgent Care. Estimates suggest these 1.5 to 3 million is about a third of all concussions.

From what I've read about long term or even never resolved symptoms, the distribution is a version of a bell curve with a long tail to the right. As one study said, The longer the recovery takes, the greater the chances of a very long recovery. Ignore the left half of the bell curve. Notice how the right end starts to flatten out. A real curve of concussion recovery would be high and steep in the middle and much longer to the right with a long slow slope to the right.

Going back to my question, we don't have a lot of foreigners on this site no? Just surprised. I grew up in a war torn country and I can't remember anyone talking about concussion.

Regarding the maths. It is a rough estimate based on the flow of concussions. You are right I might be underestimating the flow because the number I use is only those who show up for care. Also I use the greek study of 0.9% symptoms beyond 1 year and made the assumption that symptoms are resolved within 4 years. I understand that this is not the case. That the distribution is right-skewed.

Here is an estimate based on the stock rather than the flow, focused on long term disability. The stock is estimated back in 2006 to be 5 million.
http://www.nacmed.com/uploads/1/4/1/...ain_injury.pdf

Clearly it could have grown since. Now PCS is only a portion of TBI (which includes moderate and severe TBIs). I have no idea. Out of total TBIs in a given year I am Concussion is around 75% (researched). But when you look at long term disability, the share of concussion must be much smaller since only a very small share last longer than a year. Assuming all moderate and severe TBIs lead to disability, there are about 1 million cases every 3 years, so the share of PCS in that 5 million pool cannot be very large...

My point is that if you are living with PCS beyond 1+year you are a part of a very small population that is very likely less than 1% of population...

That population is likely larger than they think because most with PCS symptoms stop complaining to doctors so they fall of the radar so to speak. .

Very few with PCS apply for or receive disability because most can struggle along with their symptoms. It is the more serious mTBI's and TBI that are most of the statistic. Plus, it is difficult to document injury and symptoms because the same symptoms can easily be faked.

Many with PCS end up in prisons and jails. Studies show that 60 to 80 % of the incarcerated population are living with symptoms from head injuries.

Attempting to put numbers to PCS is difficult.

I think the figure of 0.9% with prolonged symptoms beyond a year is dubious as many just live with the symptoms and give up seeing the doctor. Some even have symptoms without realising it. It also depends on what criteria the Greek study used to define recovery. I'd say the true figure is much higher.