What did they say is causing your husband's nerve issues in his spine? I had painful nerve stabbing in my right upper leg every day for about a month, which has stopped since the last prednisone reduction, thankfully. A search for the symptoms found Spinal Epidural Lipomatosis, a buildup of fat in the spinal cavity, most often caused by fat redistribution while taking steroids or by being overweight. It causes pressure on the spinal nerves which can affect nerves in the legs.
https://pmc.ncbi.nlm.nih.gov/articles/PMC8567763/#sec15
I toughed it out, hoping that pred reductions and a re-normalisation of fat distribution might fix it. I don't know what made it go away and my problem may not have been that at all, though it was certainly nerves, so I make no assumptions about your husband's ailments. I understand your hesitation about surgery when something less invasive may fix it. Is it PMR, is it prednisone side effects, is it something else, who knows? Good luck to you both.