Inconsistent venous opacification: a pitfall of epidural venography.

The lumbar epidural venograms of 45 consecutive patients with prior normal or equivocal myelographic examinations were reviewed. Each venographic injection was performed using transfemoral double-catheter technique, abdominal compression, Valsalva maneuver, and serial filming for 12 sec. There was a 30% incidence of false "occlusions" of epidural veins suggestive of compression by a herniated intervertebral disk. These false venous occlusions were demonstrated to be such by both subsequent opacification of previously nonopacified veins and lack of opacification of previously opacified veins during repeat venography. In view of the significant incidence of spurious venous occlusions in this series, It is recommended that epidural venography with single injection should be interpreted with caution except for normal studies.