Acquired degenerative changes of the intervertebral segments at and suprajacent to the lumbosacral junction. A radioanatomic analysis of the nondiscal structures of the spinal column and perispinal soft tissues.

A review of the imaging features of normal and degenerative anatomy of the spine on medical imaging studies shows features that have been largely overlooked or poorly understood by the imaging community in recent years. The imaging methods reviewed included computed tomography (CT) with multiplanar reconstructions and magnetic resonance imaging (MRI). A routine part of the MRI examination included fat-suppressed T2 weighted fast-spin- or turbo-spin-echo acquisitions. As compared to the normal features in asymptomatic volunteers, alterations in the observed CT/MRI morphology and MR signal characteristics were sought in symptomatic individuals. Findings in symptomatic subjects which departed from the normal anatomic features of the posterior spinal elements in asymptomatic volunteers included: rupture of the interspinous ligament(s), neoarthrosis of the interspinous space with perispinous cyst formation, posterior spinal facet (zygapophyseal joint) arthrosis, related central spinal canal, lateral recess (subarticular zone) and neural foramen stenosis, posterior element alterations associated with various forms of spondylolisthesis, and perispinal muscle rupture/degeneration. These findings indicate that the posterior elements are major locations of degenerative spinal and perispinal disease that may accompany or even precede degenerative disc disease. Although not as yet proven as a reliable source of patient signs and symptoms in all individuals, because these observations may be seen in patients with radicular, referred and/or local low back pain, they should be considered in the evaluation of the symptomatic patient presenting with a clinical lumbosacral syndrome. Imaging recommendations, in addition to the usual close scrutiny of these posterior spinal elements and perispinal soft tissues on CT and MRI, include the acquisition of high-resolution multiplanar CT reconstructions, and fat-suppressed T2 weighted fast-spin- or turbo-spin-echo sequence MRI in at least one plane in every examination of the lumbar spine.