Ricks,
Don't believe all the horror stories you read first of all.

No, they are not pleasant but they aren't horrible either. At least they aren't for me. I say it all the time...I actually prefer injections over meds because they get at the source and work for me nine times out of ten. My husband also gets them and says the same thing I do. And to be honest with you my PM is out of the country at the moment but the minute he gets back in town I am going to beg for an injection!
Okay, in all seriousness sometimes they work and sometimes they don't. But if the doc already knows the culprit and performs what I THINK will be a Selective Nerve Root Injection based on what you have said, you should get some relief. My husband just had this done for the L5/S1. Also know that they use numbing medicine so you might feel instant relief. The numbing med will wear off and then it can take anywhere from a week to two or three weeks before the steroid kicks in. For me there have been times it took only a week and at others more like three.
And just know I get all kinds of injections in my neck and lumbar periodically and I am not paralyzed yet. Just make sure your doc uses Fluoroscopy...it is an xray machine that helps him guide the needle. If he does NOT have this...run don't walk! You never want a doc to go in blindly. Other than that...you should be fine. And if you are REAL anxious, call the doc and ask about taking a Valium or Xanax to calm you down. They will usually let you do that. OR...almost forgot...some docs will put an IV in and use Versed. You can ask about that too.
Good luck!