It's been 5 months since the concussion and I'm still completely exhausted and in bed all the time. I've had Chronic Fatigue Syndrome for many years, but this level of fatigue is far more severe.

Does anyone know what exactly causes the fatigue in PCS?

It could be a hormone malfunction.

Are you taking any meds ?

@CBS64

The underlying cause for fatigue caused by PCS is most likely not the same from person to person. That being said, different hypothesis have been presented to try and account for the fatigue caused by tbi.

The first hypothesis is disruption/reduction of the hypocretin/orexin neurons in the brain. Orexin is a wake-promoting neuropeptide produced by a small cluster of approximately 30.000 neurons in the brain. Changes in this system could be a cause of fatigue, at least in people with severe tbi [1].

The second hypothesis is, that the reduced ability of glutamate recycling and reuptake in synapses by both astrocytic- and neuronal cells, cause an excitotoxic build up of glutamate in the synapses. This toxic build up of glutamate causes the brain to slow down and require more rest in order to protect itself and clear the synapses [2].

Other hypthesis include disruptions in the brain stem and/or chronic inflammation processes like cytokine production, however research is still ongoing in all of these areas.

[1] Loss of hypocretin (orexin) neurons with traumatic brain injury


[2] http://www.lakartidningen.se/engine.php?articleId=6451 [Swedish article]

-GlassHead

The fatigue is a very difficult symptom for me. It is not resolved by sleeping! Often after brain injury, more areas of the brain are utilsed to do the same task as before, which may cause great fatigue. Hopefully over time, the brain will become more efficient!

Here are two useful links that helped me and my spouse to understand a bit more:
http://bianj.org/Websites/bianj/imag...igueandtbi.pdf
http://www.brainline.org/content/201...r_pageall.html

Hope you feel better soon.
M

Most of my symptoms began about four months after my accident. At five months I began admitting to myself I was not really improving, but was getting worse. Then at seven months, the bottom fell out. Although I have evidence I was doing things and occasionally journaling, I have almost no memories for the next year, and only in the last few weeks have I begun leveling off and possibly improving, nearly two years after my accident.

It is my understanding that diffuse axonal tearing, caused by rotational injury in which denser parts of the brain rotate faster than less dense areas, can cause a cascade of dying neurons, which release toxic levels of neurotransmitters when they die, which in turn causes the death of more neurons. The effect is like an extreme overdose of antidepressants. The dying overwhelmed neurons need rest. *admin edit*

Your brain uses more energy than any other part of your body, when it is injured or concussed your energy reserves are depleted as a result. During PCS your tension and arousal levels are high and this also leads to reduced concentration and increased fatigue. Everything becomes an effort and it takes a long time to get over, but resting is the right course of action.