Can the severity of a brain injury be measured?

  It's difficult. You need usually to have a neuropsychologist. They have a battery of tests they give to people. Often times it's not obvious that there's a brain injury. People have word finding issues, other subtle things. Maybe they're short fused, things like that. A neuropsychologist can run a battery of tests and determine what your cognitive, they call it a cognitive function, can be. Those tests can be very informative.