I am epileptic and it has been triggered a couple of times by claustrophobia on long haul flights, once I had a full freak out too and came round to find a couple of FA's had strapped me into a bussiness sleeper seat with the edges padded with blankets and pillows! Another time when I was put in the middle of a row between two big guys and the bloke in front reclined his seat straight away I just lept out of my seat screaming and ran for the door, that was a bit embarrassing really.
As most of my flying is for work now I get to fly up the front of the plane most of the time which is so much better but I still let the FA's know, just in case.
Before that I always called the airline soon after booking my ticket, and again a couple of days before flying to tell them I was going to be a tricky passenger and it was in their best interests to put me in a seat with a bit of space around it.
I also have some medication from my nurologist which is an anti-spasmodic but acts pretty much like a tranquillizer and hence makes me a bit zombie like.
Having the help and support of the staff on the plane does make a huge difference, only rarely have I come across FA's that dont understand how traumatising claustrophobia can be, the vast majority seem to know exactly when a big smile and a bar of choccy can make things so much easier to deal with. Once a wonderful guy was sitting opposite me in the crew jumpseat making silly faces as we waited for take off, turning my nerves into a fit of giggles. Another thing that has helped is letting me board last to reduce the time sitting on the plane while everone else gets on, also it means that I am still busy faffing with my stuff when they close the doors.