[Current imaging of spondylolisthesis by isthmic lysis]

Unilateral spondylolytic spondylolisthesis may cause lateral tilt of the overlying spinous processes towards the normal isthmus on PA views. Bilateral spondylolytic spondylolisthesis is generally located at the L5-S1 level. The vertebral shift is usually moderate. Instability at the level of spondylolisthesis may be demonstrated by stress lateral views but is uneasy to quantify. In case of sciatica associated to spondylolisthesis, foraminal stenosis is probably the most frequent cause but foraminal compression of the spinal ganglion is difficult to assess on imaging.