When I was blasted in the rear end by a drunk driver back in 2000 I was all over his insurance company about this very issue. I had refuse medical attention at the scene after his Fleetwood and my F350 were towed.
After weeks of haggling with them I made the off hand comment that lately I was having headaches and my right hip had shooting pains occasionally and man that flat out paid me 19500 for a truck I had bought 2 years earlier for 15200.
It ended up being for real though as I had L4,L5,S1 back problem, oh and torn labrum in my hip that put me on the surgeons table and off work for 6 months.