Chronic low back pain.

Most episodes of low back pain are mechanical in origin and resolve within a 12-week period. These acute episodes of back pain are associated with muscle strain and intervertebral disc herniation with radiculopathy. A smaller proportion of individuals have back pain with a duration greater than 12 weeks. These patients have back pain secondary to a wide variety of mechanical and nonmechanical disorders. The mechanical disorders associated with chronic low back pain include osteoarthritis and lumbar spinal stenosis; the nonmechanical disorders include infectious, neoplastic, rheumatologic, endocrinologic, vascular, and gynecologic. The clinical symptoms associated with each variety of disorder helps guide the appropriate diagnostic evaluation. Plain roentgenograms are useful in documenting the presence of spinal stenosis, benign or malignant tumors, osteoporosis, sacroiliitis, and spondylitis. CT scan is helpful in defining the bony alterations associated with malignant tumors and the vascular abnormalities associated with aneurysms. MR imaging is the technique of choice to document the extent of malignant processes and the presence of endometriosis in the pelvis. The therapy of these entities are specific for the disease entity causing the chronic low back pain. Although most of the disorders that cause chronic low back pain cannot be cured, therapy can decrease pain and improve function of the symptomatic patient.