There is an injury that looks like PTSD, which comes from being too close to a powerful explosion. But you're not likely to have it unless you're a vet. The brain, by and large, is pretty well protected. There's the scalp, the skull, and a layer of fluid. They do a pretty good job. Even against some things that you might think would mess up the brain (like getting thrown throw a windshield in a car accident, or hitting a dash board....which causes the brain to swell, but once the swelling goes down (if you live through it) most people are fine. It does mess up the memory, but it doesn't cause AS. Brain injuries are extremely complicated, there is a whole field of medicine that studies them. Rode a medivac helicopter with a young woman who had been slammed head first into an engine block at what the cops figured was 30 miles an hour (no I wasn't in the accident). At one point, she was awake before they operated, and, because I was the one with the movie camera, she started to try to talk to me. I said nothing (those were the rules) except I'll get a doctor if you want to talk. Two months later, I was eating lunch in the same hospital, and this pretty young woman on crutches sits down across from me, sees the video camera and says "remember me? I met you in an operating room a few months ago." I don't know how she pulled through it, but one of the doctors later said it was the fact that her skull and aricnoid fluid protected her brain. So no, I don't think a head injury can cause AS. Death, yes. but not AS.
Beentheredonethat