Sorry to hear you are still having all these CNS problems. As you probably know, I have MS, as well as SLE.
Maybe some of what I experienced during my diagnosis could help you somehow. After I had MRI's that showed white-matter lesions, they went straight to a lumbar puncture and then nerve conduction and evoked potentials tests. I don't recall a spinal MRI, but my memory of that time isn't very good. I get total numbness, but rather than being bilateral, mine is unilateral, from about my mid thighs down. I lose all sensation, but still have full control of my legs. For eyesight, I've had no double vision, instead I get nystagmus-both eyes, and optic neuritis, usually the right eye.
My first symptoms were the leg numbness and falling hard, like somebody flipped a switch and my legs just gave out. I'm 6'1" and 200lbs, so it's a long way down, and I hit hard! I also had the neuritis in the right eye, and dragging of my right foot. One ongoing problem is diminished sensation in my fingers which causes me to drop things all the time because I can't sense pressure. Stuff just slips out of my hand. I have to be careful because I can burn my hands and not realize it.
The main line of defense for me right now is IV Infusions of Methylprednisolone. I get the infusions three days a month, and it takes about 90 minutes to do each one. It doesn't have the side effect of weight gain for me, just jitters and insomnia/nightmares when I first started it. It does a pretty good job of controling my MS symptoms.
If it's MS, the meds available are fairly effective, and fast acting. There are quite a few treatment options as well, and many seem to be effective. I hope you get this figured out soon. CNS problems can be a real nightmare to deal with.