The sense that I got from the article is that unlike "normal" TBIs, this type of brain trauma is very difficult if not impossible to see on a scan. The symptom

The sense that I got from the article is that unlike "normal" TBIs, this type of brain trauma is very difficult if not impossible to see on a scan. The symptoms, on the other hand seem very very similar. The progressive degradation in cognitive ability with exposure to explosions is (to my admittedly untrained eye) exactly the same as that of multiple concussions. Which is not to say I didn't find this article interesting. I think the key difference between TBIs caused by explosions and those due to physical trauma is purely because there's no obvious lesion on the brain visible in a scan. As a result, the military treated it differently, which the article points out was a fundamental error that the military has now taken steps to correct.