Figure 2.

With lumbar stenosis and degenerative spondylolisthesis, there is a marked increase in lateral and foraminal stenosis at the level of the slip. Note in this illustration (Joseph A. Epstein M.D., copyright Nancy E. Epstein M.D.) there is greater right lateral/foraminal compromise attributed to greater hypertrophic changes of the right facet joint and some extrusion of the degenerated synovial cyst into the right L4–L5 foramen compressing both L5 roots (seen here) and also foraminally/superiorly the L4 root