Suggest Treatment For Numbness In Legs While Suffering From Spondylolisthesis

I have spondylolystheisis with severe neuroforamina stenosis. I have now developed numbness on both legs and I don t want a big invasive surgery. I woud like some minor invasive surgery to releive me of this pain. L4 slides into L5 and this has been going on for 8 years. HELP