I'm not a doctor or medical expert, I can only relate to you my experience having had a number of major lower back surgeries over the last 20+ years now, and tests that I've been through along with the results of those tests as I understand them.
First it's good news that your MRI of your lumbar and thorasic came back normal. The MRI w/Contrast would show the structure of your spine, alignment, and any abnormalities (such as herniated or slipped disc's pressing on a nerve or causing debris in the spinal canal thus affecting sensory perception in your legs.)
I'm somewhat confused/concerned that you're being prepped for surgery without the doctors having a clear indication of where the problem is that's causing loss of sensation in your legs. (Again, I'm no expert and I'm sure they know more than I do.) I suppose it's possible that they'll want to do exploratory surgery to attempt to determine the location of the nerve impingement (assuming it's a nerve root impingement.)
In that case, your doctor should explain to you clearly what they believe they're looking for and how they'll know they've located the problem.
In my case, back in 2008 I had exploratory surgery for a nerve root impingement that did not show on an MRI w/Contrast. Before I went in for surgery, the Neurosurgeon, his team and I talked through the surgery, and the electronic device that would be wired up to my lower back,legs and toes to help them find the source of the impingement. I'm fortunate that my surgery to alleviate that impingement was successful and I recovered full use of my left leg.
If your doctor is talking to you about surgery, make sure you understand what it is he/she is looking for, how they'll know when they find the problem, and what your recovery time is expected to be.
Please do post a follow-up.
Just saw the doctor. They are trying to get me admitted to the therapy floor for extensive therapy. In the meantime, I get therapy here, just not as much as I would on the 4th floor. It would still be treated like a hospital stay in that I get fed and bathed etc...have access to tv and internet...just much more therapy daily. Sounds like the issue is excessive swelling putting pressure on the nerves and keeping me from walking. I was taught to transfer myself from the bed to a wheelchair and took for a stroll down the hall and back. Hoping and praying the swelling goes down soon and that I will walk again soon.