"Sgt. Sanes got hit with two rounds simultaneously on his position within five meters," platoon Staff Sgt. Anthony Fuentes told TIME a few days after the fight. The rounds landed just as an Afghan Army sergeant was firing a recoilless rifle. The blast knocked him to the ground and his round exploded inside their position. After that, "our weapons squad leader [Sanes] was giving fire commands to a rock. That's what happened in our case. They got nauseous, they couldn't vomit (but they wanted to), they couldn't focus and they had double vision,

The pounding that Sanes and his men took may have been intense but multiply it by hundreds and thousands of incidents over a range of severity and you have the potential causes for what may be a murkily diagnosed set of symptoms affecting U.S. servicemen and veterans