Correlation of electromyography with computed tomography in evaluation of lower back pain.

High-resolution computed tomography (CT) of the lumbar spine in 80 consecutive patients with lower back pain was correlated with electromyography (EMG) and with the clinical outcome at one-year follow-up. Forty-two patients had abnormal EMG findings that could be explained on the basis of anatomical defect(s) seen on CT. Nine had normal CT scans but abnormal EMGs, and five patients had normal EMGs but abnormal CT scans. Thirteen of the 80 patients were further investigated with myelography, 22 patients underwent surgical exploration, and the remainder received conservative therapy. In the majority of cases, surgery confirmed the abnormal CT and EMG findings; in some instances, however, myelography and/or surgery confirmed the abnormality only at the level demonstrated on EMG. The CT and EMG often agree. However, an abnormal EMG seems to correlate better with the demonstrated course of radiculopathy than CT.