We performed magnetic resonance imaging on sixty-seven individuals who
had never had low-back pain, sciatica, or neurogenic claudication. The
scans were interpreted independently by three neuro-radiologists who had no
knowledge about the presence or absence of clinical symptoms in the
subjects. About one-third of the subjects were found to have a substantial
abnormality. Of those who were less than sixty years old, 20 per cent had a
herniated nucleus pulposus and one had spinal stenosis. In the group that
was sixty years old or older, the findings were abnormal on about 57 per
cent of the scans: 36 per cent of the subjects had a herniated nucleus
pulposus and 21 per cent had spinal stenosis. There was degeneration or
bulging of a disc at at least one lumbar level in 35 per cent of the
subjects between twenty and thirty-nine years old and in all but one of the
sixty to eighty-year-old subjects. In view of these findings in
asymptomatic subjects, we concluded that abnormalities on magnetic
resonance images must be strictly correlated with age and any clinical
signs and symptoms before operative treatment is contemplated.