These are HIGHLY addictive. Xanax won't get you high, but Valium will, so I prefer Xanax for muscle spasms.
I am not sure if they stop the pain or allow you to not care. I know that when I have walked five miles and my hip is killing me, I take a Valium and it stops. I take the Xanax to sleep.
The down side is that, when you try to wean off or to stop taking these, every pain that you ever had in your life comes back to haunt you.