Actually, complex concussion is a term used by the sports trainers, etc. that was suggested by the International Conference on Concussion in Sports. I have never heard it used by main stream medicine. The sports concussion people use it to define those concussions with lasting symptoms keeping the athlete out of the game. In reality, there is no such thing as a simple concussion. It is a term use poorly to justify returning to play without further concussion follow-up.

Any attempt to grade concussions if fraught with errors and risk. When the science is such that they understand the physiological mechanism of concussions, maybe they can classify them by such understanding.

I hope the term complex vs simple gets rejected from concussion terminology since it creates a serious false sense of security.

I know people who were comatose who have much better cognitive and memory function than many of use with 'simple' PCS.

btw, That thread was from July 5, 2010.