--that, given your history, the first thing to look at is your lower spine area. there may be impingment of nerves from scar tissue and the like, and the fact that your symptoms do change significantly with position does seem to point to something biomechanical. It may be a problem with the spinal cord itself, or with the nerve roots in the cauda equina area.

The other thing to check, just to make sure, is the rest of the spine--problems in the cervical area, especially, can cause problems with the lower body as well as the upper (though it seems too many neurologists forget this).

Have you take a look at our spinal disorders forum?

http://neurotalk.psychcentral.com/forumdisplay.php?f=22

There's a lot of detailed expertise there about post-op symptoms/complications and such.