Wait a few Months and the long term brain stem injuries will begin to show up.

No short term memory.
Inability to perform basic math calculations.
Inability to control muscles in hands and feet.

The human body was never designed to absorb the blast of an IED and all the body armor/kevlar helmets do is allow the body to spasm within the shell (think of a boxers brain after a uppercut or right cross) your skull stops moving but your brain is still rotating back and forth or up and down, each movement breaks another nerve connection in the Medulla connection to your spinal column.

and one day you wake up and cannot remember how to tie your shoes...

Happened to a friend's kid brother 6 months after he got back from Kandahar after their MPV was blown 30 feet into the air by a SMALL IED.