Most common types of this come on slowly (diabetes for example). But you describe sounds like an aggressive cause, probably from something affecting the immune system...that is why they will do a biopsy, to see if it is lymphoma or sarcoidosis.
Once they find out the cause, they will know how to treat it...
But treatment only stops the cause, then you have to wait for the nerves to recover. This may take months and may not be complete.
So be patient...and if the doctors aren't certain, ask for a referral to a bigger hospital that has a specialty clinic in the disease.
I have only seen one case like your wife and we had to refer him out of state to get diagnosed. The treatment took time but after 2 years he was our of his wheelchair.
You are in my prayers.
It started out with a lumbar puncture and suspected inflammation of the spine. They prescribed steroids and her condition seemed to improve. They have now stopped the steroids as they focus on her lungs, and her legs have gotten worse. Then they knocked her out and stuck a tube down her throat and into her lung to take a sample. That wasn’t conclusive enough so now they are going in, either through her side or her chest we don’t know where yet. She’s had lumbar punctures, brain scans and MRIs. We took reports of everything they have done so far to our GP and, after a thorough read through, came to the conclusion that it’s complicated. They are trying their best but it looks like a fishing expedition.