Quote
Saguaro
Ever been hit hard enough to leave a bruise somewhere on your body?
Unless you bruise easily, it usually takes a blow that hurts quite a bit.

But then there have probably been times when you were hit pretty hard, and wondered if there would be a bruise, and there wasn't.
That hit hurt, too, but didn't cause bleeding. The pain was only a warning, but not damage.

I'm using bruising as an analogy. I'm not saying that a concussion is the same as a bruise.

Just as it may be possible to take a hard hit on soft tissue, a hit that really hurts, but have or not have a resulting bruise.

So it may be possible to take a hard blow to the head, maybe one that you really feel, and have a concussion, or not have a concussion.