My fiancée is suing the driver that ran her over when she was 6 years old (she's 27 now). She's just found a 'shunt' in the brain which was found with an MRI which is effecting the function of her eyes and was missed by the idiots posing as Dr's who attended her in A&E :bang:.
So yes it goes without saying any time frame's possible. But in my experience if he's mugging you off just go direct to insurance.
Good luck with this, hope they can prove that this was the cause of the issue, from personal experience I had trouble proving even with evidence a few years back. Would like to know the outcome and if I can help in any way let me know. I had to fight the solicitors (mine) as well as the doctors. I even managed to prove the tests we use here were flawed and the private and public sector was wrong as I spoke to the guy (US professor) who invented the test. Unfortunately I couldnt afford my day in court, so had to settle, but got much more than was originally offered.