Radicular symptoms are usually related to the level of the responsible lesion; the L5 root is compressed in the L4–L5 space or foraminal or extraforaminal level of the L5–S1 space. In contrast, compression in the L3–L4 space affects the L4 root. However, in some patients the level of stenosis on the image does not correlate with the neurological findings. The cauda equina are bundles of nerve roots within the thecal sac and at the L3–L4 intervertebral level, the L4 root is situated anterolaterally and the lower roots such as L5 and S1 roots tend to take up a more medial central position. According to the specific anatomical structure of the lumbar thecal sac, a severe compression of the thecal sac at the L3–L4 level may damage the caudal roots such as the L5 and S1 roots
Citation: Eguchi Y, Ohtori S, Toyone T, Ozawa T, Yamauchi K, et al. (2012) Surgical Experience in Cases of L5 and S1 Symptoms Caused by Upper Lumbar Spinal Stenosis of L2â€“L3 and L3â€“L4. J Spine 1:105.