The Journal of Bone and Joint Surgery, Vol 70, Issue 9 1279-1290, Copyright © 1988 by Journal of Bone and Joint Surgery, Inc
False-negative lumbar discograms. Correlation of discographic and histological findings in postmortem and surgical specimens
T Yasuma, R Ohno and Y Yamauchi
Department of Orthopaedic Surgery, Kouto Hospital, Tokyo, Japan.
To investigate the causes of false-negative discograms, 181 lower thoracic
and lumbar intervertebral discs that had been removed as part of en bloc
specimens during thirty autopsies were studied first by discography and
then histologically. Comparison of the results of the two methods showed
that if fissures and cysts were present in a degenerated anulus fibrosus,
but did not establish continuity between the nuclear cavity and the site of
a herniation, the discogram was false-negative. Under these circumstances,
the inner fiber bundles of the anulus fibrosus were intact and their
orientation was often reversed, so that they bulged inward. This finding
suggested that a protrusion or a prolapse of tissue from just the anulus
fibrosus might have been developing. Ten of the fifty-seven discs that had
such changes in the orientation of the fibers had a histologically proved
protrusion or prolapse of the anulus fibrosus. However, the discograms
showed protrusion in only six of the ten discs and demonstrated a
false-negative result in the other four. The cases of seventy-seven
patients in whom discography had been performed and a herniation had been
subsequently confirmed at operation were also studied. Fifty-nine of the
patients had a protrusion and eighteen had a prolapse of the disc. The
discograms were falsely interpreted as negative in 32 per cent (nineteen)
of the fifty-nine patients who had a protrusion and in 56 per cent (ten) of
the eighteen who had a prolapse. Histologically, the prolapses were
interpreted as protrusions of a portion of the anulus fibrosus. It was
concluded that false-negative discograms are more frequent when a
protrusion or a prolapse involves the anulus fibrosus rather than the
nucleus pulposus, and that a negative discogram does not exclude the
possibility of extensive degeneration of the anulus fibrosus.
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