How can you tell the difference between slight and transient brain injury?

TIA. You mean transdient ischemic attack, this a pre-stroke syndrome.This need to be treated as soon as possible before it developed into a completed stoke.Other name is acute. Brain attack.
Brain injury. Slight brain injury is nonspecific. That means the brain has sustained trauma, which is not significant. Transient brain injury means that the brain sustained a problem, but that this problem is now gone.