@gently I think the extra "space" that you get by reducing inflammation with a steroid spinal injection is minimal, and when the steroid wears off and is cleared from the body, the inflammation returns to the damaged area and that "space " must shrink away. The risk to the nerves is from compression. With severe compression nerves can die and may not be able to regenerate. There is research going on of course in regenerative medicine, but there do not seem to be miracle cures for spinal cord injuries at this time. But that being said, there was some research at Mayo where a patient with a spinal cord injury was able to walk again with stem cell research, but that was unusual, and most patients in the study did not get such good results. Most spine patients tend to have compression over a period of time that eventually surgeons decompress to save the functional capabilities and prevent further damage.

I guess you can think of it in that steroid injections could buy some time or slow the progression of compression perhaps, but that also depends on how fast things are changing. That may not be the same for everyone. I know with my own MRI imaging of my herniated cervical disc that the amount of bone spurs growing around the herniation doubled in 9 months. My neurological and pain symptoms were also increasing at the same time. I regard the nerves as being at risk if there is compression or instability in the spine. My disk had collapsed by 50% and when I would side bend my neck, I could hit those nerve roots and cause a burning pain in my arms. I didn't have boney growth around the nerve roots, and it was simply that because the disc got thinner, the vertebrae were closer together and didn't have enough space to move without hitting the nerves. Since my fusion corrected that, I can no longer bend at that level and the space for the nerve roots is preserved.