NavList:

Frank you wrote:
" am not sure I understand what is meant by compression medically, but I assume it's brain injury, an extreme concussion?"

I’m not a medic, but last week I happened to update my long lapsed first aid certificate with a six hour course.  I’ve probably forgotten most of it already, but the thread and the photo of the Co-Pilot seemingly OK prompted one memory.  In the simplified nomenclture designed for the volunteer first-aider, concussion is likened to a “brain shake” from which you gradually recover; a “compression” is when a segment of skull bone is depressed into the brain causing bleeding inside the skull.  The effects can strike some time later.  It sounds very like what Tom describes.  It’s a long time since any of my kids attended ER after a fall, but in the UK they used to give the parent a slip of paper when they took the child home again saying roughly “It looks like your child’s OK, but bring them straight back if you get any of the following signs or symptoms.   Dave