--or it may not; not only are EMG/NCV tests not always a reliable indication of the extent of nerve damage (one can have annoying and considerable symptoms of compression, especially sensory, and not show much in the way of deficit), but if the smaller, unmyelinated fibers are involved, those tests, which can only measure larger, myelinated fibers, may not show anything.

Compression of nerve at the knee head, by the way, is actually very common--I have a degree of it in my right leg that extends down the front of my right calf (it's a slight numbness, not what you're feeling, but I empathize). This is often found in people with imparied glucose tolerance, but also often in athletes (compartment syndrome, in which bulging muscle actually presses on and displaces nerve), and, of course, in people who assume squatting and bending positions ("strawberry pickers' palsy"), or sit cross legged often (I'm certainly guilty of the latter). The knee is also a place, like the spine, at which osteophytic spurs can grow as we get older, and these can compress nerve.

Most people who have systemic nerve damage from impaired glucose tolerance, other metabolic problem, or autoimmunity or toxic assault will be more prone to compressive effects from then on--there is actually a "double crush hypothesis" that states that a second, compessive assault on a nerve can combine with other reasons for nerve dysfunction to produce symptoms that would be greater than the assumed sum of their contributing parts. I don't know if you've had a thorough workupf or more systemic causes of neuropathy that may be contributing to all this, but it can be a long (and expensive road) of ruling out possibilites. Take a look at the Liza Jane spreadsheets at www.lizajane.org, and see which of these tests you may have had (the sheets were designed to be a very comprehensive listing of tests for neural symptoms and a way to track test results over time)--I'm betting not a lot of them--and it may be a way to encourage neurologists to delve deeper.