Doozer,

You said "So Mark, if a person had a concussion and their symptoms are consistently bad with a certain activity, with zero improvement over a very long period of time would that indicate that the nerves handling that activity are dead and gone? As opposed to symptoms which only come and go in general, which would suggest that nerves are injured and, given enough time, able to regenerate to almost their previous abilities? "

You are trying to read too much into my comments. You can not ask such a general question and get a specific answer.

If a certain activity causes symptoms, one can often see what it is about that activity that is causing the symptoms. Often, it is only a limited characteristic of the activity causing the problems.

None of these issues are about nerves dying.

Can you list specific activities, the surrounding circumstances when you do those activities and the symptoms that result ?

And, regeneration of nerves, even to almost their previous abilities is a false statement in the context you are using it.

Symptoms come and go because of triggers, etc. that exceed the tolerance of the brain as it uses large numbers of complex nerve pathways. Some nerve pathways are stronger and more tolerant than others.

Trying to define exact cause and effect is a losing battle. Even the experts cannot do it.

The point of my comment is that if you can do an activity during your best times, that should give hope that you can improve on that function.

What activity/function have you not been able to do for a long time ?