Thoracolumbar Spine Anatomy and Pathology - Spinal Stenosis

Severe degenerative spinal stenosis at the L4–L5 level in a 70–year–old with a history of intermittent claudication and occasional radicular leg pain. The central and lateral stenosis is most pronounced at this motion segment level and is almost exclusively caused by soft tissues. Anteriorly, the circumferentially "ballooning" disc narrows the thecal sac anteriorly and also completely obliterates the retrodiscal portion of the root canals (neuroforamina). The facet joints, especially the superior articular processes are moderately hypertrophied, rendering the joints a ball–and–socket configuration of the facet joints. Note the effusion posteriorly of the left facet joint and the sclerotic meniscoid tag posteriorly into the right facet joint. The thecal sac is severely compressed posterolaterally by the thick ligamentum flavum and assumes a triangular slit–shaped configuration in which the roots of the cauda equina are tightly packed without any cerebrospinal fluid surrounding them. The two ligamenta flava are continuous posteriorly with the thick and degenerated interspinous ligament.