TBI means Traumatic Brain Injury whereas a stroke may not seem to fit the definition of traumatic in a classic way. It doesn't matter how you come by an injury to your brain it is traumatic be it a car accident, a fall, lack of oxygen, or a stroke, the results are the same and equally devastating. All BIs are traumatic no matter how they occur. I thought this is a great explanation. I found it to be a very good breakdown of technical stuff into human readable language. The great thing about it was that this was a post by a member of a mailing list I belong to called SoTbi (survivors of traumatic brain injury). I think Scot Hume has a gift where he can take something that was explained to him by his Neurologist & write it so it makes sense. If it also helps a non-TBIer to understand us a little --great!

  "While I don't have a great solution yet, I can explain the fatigue a bit. My neurologists explained that when you get hit, (when the brain suffers damage) a whole bunch of neurons get killed. Around those neurons are more connecting neurons and each survives by firing periodically to keep in touch with all its friends. Sort of like someone sitting around in their house and calling their neighbor once in a while.

Scattered throughout the brain are little "dead" areas and their friends next door keep sending out signals to try and reach them. The problem is that there isn't anybody to send the signal back. So the live neuron gets frantic and starts sending even more signals. This pushes it towards anaerobic respiration which is when the cell firing threshold allows it to fire uncontrolled and deplete the oxygen supply. Uncontrolled, this leads to a really nasty event called neuronal death which is a fancy way of saying a lot more brain cells keep firing until they die. Fortunately, your brain is pretty smart and figures out that this uncontrolled firing isn't a very good idea. So it just starts turning off sections in an attempt to regulate things and keep from doing more damage. This makes you physically tired and you lay down to rest.

Now, if a neuron fires and doesn't get a response and has enough oxygen, it starts to extend its axons out farther and farther. The neurons on the other side of the damaged area do the same thing. Hopefully, they are close enough that they make a new connection and just skip over the lost cell. I sort of think about it like three houses on a block. The middle house burns down and the two neighbors start throwing telephone cable across the lot towards each other. Hopefully, one of the neighbors catches the line and a new connection is created.

I was told that the key is to just accept fatigue as a good indicator of when to stop and not try to push through. The old saying "No Pain, No Gain" really doesn't work with brain cells. So as I start to get tired from walking to more cognitive things like math, I try really hard to use fatigue as the mark of when to stop or take a break. Stopping is never as easy as it sounds. Even trying to be careful, I find that I have to push through sometimes. Still, I started out not being able to walk and carefully worked my way back up to climbing and skiing.

I know this is kind of long, but there is hope that all kinds of new pathways are being built and eventually the fatigue level goes down as these new routes become the preferred path."