I've recently undergone facet block injections for slipped discs with a nerve root pressing on one of them causing the most intense pain I've ever felt in my lifetime. NOT the injections, the nerve. Sadly for me they didn't work, but the procedure was very simple. It was done in the radiology dept with a local first, then they injected a lidocaine type of medicine into the spinal canal first. The injections itself was just a pinch. I didn't even feel the steroids being injected after that. A few hours later I did have a bit of additional pain but to put your mind at ease, the papers they had me sign stated that it had been twelve years since the hospital had had any complications with the procedure. I'm sure you're aware that any procedure has it's dangers but I would not be too fearful of this.
I also underwent a spinal during the birth of my daughter that did go wrong and I experienced spinal headaches that were aleviated with a blood patch. They draw your own blood, about twenty cc's and then inject into the area around the tiny hole in the spinal chord. The relief was immediate.
Good Luck to you and yours. I hope you are able to enjoy a Happy New Year.