--for such symptoms to be traced to pressure on nerve roots in the lower lumbar and sacral spine areas.

What that would mean, of course, is that technically you don't have true tarsal tunnel, as the symptoms are starting higher up than that area. You could have some compression going on in the foot ankle area as well, though--the so-called "double crush phenomenon".

Neural symptoms from widely different causes can "feel" exactly the same--they may be caused by peripheral nerve problems, problems in the spine, or even in the brain--which is why investigation into their causes are often long, expensive and rather process of elimination.