I mangled the L3 to S1 discs in my back in the Army. A couple of years ago I had 30% of the L4-L5 disc removed because it was pressing my spinal cord against the lamina (bones that cover the spinal cord) and the L5 root nerve.
I woke up feeling good a few weeks ago. I rode the DR650 to work. I started having muscle spasms in my lower back about an hour later. That lasted all day. I rode home that evening and couldn't lift my right leg back to get off the bike. Tuesday I woke up with a very sore lower back, and numbness in both legs. I hobbled down the stairs went to the doctors office to find out what was wrong.
That's the long version.
Diagnosis: I ruptured the scare tissue on the L4-L5 lumbar disc. The disc jelly has spread from the L4 to the S1 root nerves on both sides of my spinal cord. The MRI pictures I looked at yesterday looks like a cloud covering most of the lower portion of my spinal cord. That is what's causing the numbness, pins and needles, burning sensations, muscle spasms and occasional weakness in the legs.
Prognosis: I have to do an EMG Tuesday before the VA will decide what action to take next. Since the L4 and L5 vertebrae already rub so they can't take anymore out of that disc for cleanup. Since L5-S1 and L3-L4 are both damaged they won't do a disc replacement. I'm a very likely candidate for fusion on L4-L5 and L5-S1. I don't want that option, but it's the most likely at this point.
In short, I'm retired from riding anything until I get something done to fix my back. I'll have to live vicariously through others until I can ride again. So keep riding.