Differentiating lumbar disc protrusions, disc bulges, and discs with normal contour but abnormal signal intensity - Magnetic resonance imaging with discographic correlations
Pc. Milette et al., Differentiating lumbar disc protrusions, disc bulges, and discs with normal contour but abnormal signal intensity - Magnetic resonance imaging with discographic correlations, SPINE, 24(1), 1999, pp. 44-53
Study Design. Independent evaluation by two observers of 132 lumbar discs i
n 45 patients with chronic low back pain investigated by both magnetic reso
nance imaging and discography.
Objectives. To assess some of the fundamental differences between lumbar di
sc protrusions, disc bulges, and discs with normal contour but abnormal sig
nal intensity on T2-weighted magnetic resonance images.
Summary of Background Data. Moderate interobserver agreement has been repor
ted when the morphologic terms normal, bulge, protrusion, and extrusion are
used. The validity of this nomenclature remains unknown.
Methods, Discs were evaluated on magnetic resonance images for central and
peripheral signal characteristics, height, contour, and nerve root compress
ion. Discograms were classified according to degrees of disc degeneration,
disruption, and pain reproduction.
Results. Loss of intervertebral height or abnormal signal intensity on magn
etic resonance imagery was significantly associated with disc disruptions e
xtending into or beyond the outer anulus on discograms. All 23 protrusions
(100%) and 12 of 15 disc bulges (80%) were associated with Stage 2 or 3 anu
lar disruptions and, in most instances, similar or exact reproduction of pa
in during disc injection. There was no significant difference between disc
protrusions, disc bulges, and discs with normal contour but abnormal signal
, with respect to degree of disc degeneration, extent of disruptions, or pr
esence of discogenic pain.
Conclusions. In patients with chronic low back pain, loss of disc height or
abnormal signal intensity is highly predictive of symptomatic tears extend
ing into or beyond the outer anulus. Disc bulges and disc protrusions do no
t represent discs with significantly different internal architecture, based
on the findings of discography, and are no more suggestive of symptomatic
tears than discs showing normal contour but decreased height or abnormal si
gnal intensity.