thanks yarok and alophysio, I think I see your point now yarok, excuse my small rant there. A small disturbance along the spine , distant from immediate referral sources may incurr elements of protective behaviour further along the spine. Agreed. If treatments at the thoraco lumbar area had failed to provide immediate verification of it's involvement , then looking further afield would be logical. Including other spinal segments seemingly not related. I'm with you. Dural connections , as you point out alophysio, are manifestly more complex than simply a string of fibrous tissue.
The logic of most likely first, least likely last , however , still applies.