There are many manifestations of these casualties but the treatment is simple, they have to be withdrawn from fight and rest for a period of time in calm environment.
But the problem is that the military does not want to simply return the psychiatric casualty to normal life, it wants to return him to combat! And he is understandably reluctant to go.
The evacuation syndrome is the paradox of combat psychiatry. A nation must care for its psychiatric casualties, since they are of no value on the battlefield — indeed, their presence in combat can have a negative impact on the morale of other soldiers — and they can still be used again as valuable seasoned replacements once they've recovered from combat stress. But if soldiers begin to realize that insane soldiers are being evacuated, the number of psychiatric casualties will increase dramatically. An obvious solution to this problem is to rotate troops out of battle for periodic rest and recuperation — this is standard policy in most Western armies — but this is not always possible in combat.
The solution is to treat the mentally wounded as close to the front as possible and constantly communicate to the soldiers that they will return ASAP. One could try medicate the problem away, the US and Israel used 'truth serum' with some success to release the emotion via talking out their experiences and preventing to bottle it up.