I am having a lumbar discogram. Wondering what they are like? Any permanent risk of harm?

Discogram. A discogram is used to evaluate a particular pattern of back pain that involves sitting intolerance and relief with recumbancy. Placement of needles into the disc spaces to perform a fluid pressure test should be well tolerated but there are some concerns that it may accelerate degenerative changes in the tested discs. The most common risk would be infection but the rate should be less than 1%.
Always risks. There are risks associated with every procedure. You will experience worsened back pain and possible worsened leg pain after the procedure which may last for a few days and then improve.