Sciatica is a really awful disease, particularly since it doesn't seem to be very well understood. Several people I know from a forum suffer from it and they have days where they just can't get out of bed because the pain is so bad.
It's not actually a disease in itself, but just a symptom of something else, which often goes undiagnosed.
I do know that with one of them the problem is with the nerves in their hip from an injury they had as a teenager which has never really healed properly. It just seems like a tragedy, to have a pinched nerve in the hip area that never heals right so you've always got to live with pain.
I hope that medicine keeps advancing to the point where people don't have to suffer like that anymore.