MAGNETIC-RESONANCE-IMAGING OF THE LUMBAR SPINE IN PEOPLE WITHOUT BACKPAIN

Background. The relation between abnormalities in the lumbar spine and low back pain is controversial. We examined the prevalence of abnorma l findings on magnetic resonance imaging (MRI) scans of the lumbar spi ne in people without back pain. Methods. We performed MRI examinations on 98 asymptomatic people. The scans were read independently by two n euroradiologists who did not know the clinical status of the subjects. To reduce the possibility of bias in interpreting the studies, abnorm al MRI scans from 27 people with back pain were mixed randomly with th e scans from the asymptomatic people. We used the following standardiz ed terms to classify the five intervertebral disks in the lumbosacral spine: normal, bulge (circumferential symmetric extension of the disk beyond the interspace), protrusion (focal or asymmetric extension of t he disk beyond the interspace), and extrusion (more extreme extension of the disk beyond the interspace). nonintervertebral disk abnormaliti es, such as facet arthropathy, were also documented. Results. Thirty-s ix percent of the 98 asymptomatic subjects had normal disks at all lev els. With the results of the two readings averaged, 52 percent of the subjects had a bulge at at least one level, 27 percent had a protrusio n, and 1 percent had an extrusion. Thirty-eight percent had an abnorma lity of more than one intervertebral disk. The prevalence of bulges, b ut not of protrusions, increased with age. The most common noninterver tebral disk abnormalities were Schmorl's nodes (herniation of the disk into the vertebral-body end plate), found in 19 percent of the subjec ts; annular defects (disruption of the outer fibrous ring of the disk) , in 14 percent; and facet arthropathy (degenerative disease of the po sterior articular processes of the vertebrae), in 8 percent. The findi ngs were similar in men and women. Conclusions. On MRI examination of the lumbar spine, many people without back pain have disk bulges or pr otrusions but not extrusions. Given the high prevalence of these findi ngs and of back pain, the discovery by MRI of bulges or protrusions in people with low back pain may frequently be coincidental.