Fig. 1.

An 64-year-old female with symptoms of bilateral lower limb neurogenic claudication with symptomatic improvement with a caudal epidural steroid injection. An interlaminar approach could have been considered appropriate, as well. (a) Sagittal view of a T2-weighted MRI of the lumbar spine. Note the grade I spondylolisthesis of L4 on L5 with severe central canal stenosis. (b) and (c) Axial views of a T2-weighted MRI through L4–5. Note the diffuse disc bulge in (b) and the marked ligamentum flavum hypertophy in (c), both contributing to the severe central stenosis. (d) The L5-S1 level showing no evidence of stenosis