Yup. Moreover, it's possible, and in fact quite likely, to have both. Having an IED go off near you might result in blast injury to your brain, which produces

Yup. Moreover, it's possible, and in fact quite likely, to have both. Having an IED go off near you might result in blast injury to your brain, which produces one set of symptoms. But it's also pretty likely to cause PTSD as well. That sort of thing is a harrowing experience, more so if you witnessed someone you cared about getting killed or injured in the blast as well, that's an easy candidate for setting you up for PTSD. But the symptoms you experience afterward will end up being a mix of both conditions. I find it interesting that people seemed to have figured out "shell shock" fairly early on simply intuitively. But whereas early treatments focused on it as an almost mechanical thing, and something to be overcome so that soldiers could be put back into the fight, it took a greater sensitivity to psychological issues to realize that PTSD was also a factor though in so doing there was a tendency to attribute all symptoms to PTSD. Now we've rediscovered shell-shock, but I hope we don't forget that PTSD is real and important as well. And we don't view shell-shock as simply a hurdle to overcome so we can get the greatest battlefield efficiency out of wounded soldiers. We've come a long way since WWI in how we treat soldiers, and I hope we don't regress.