Mj. Kuhn et al., LUMBAR EPIDURAL LIPOMATOSIS - THE Y-SIGN OF THECAL SAC COMPRESSION, Computerized medical imaging and graphics, 18(5), 1994, pp. 367-372
Purpose. We have identified a specific sign of lumbar thecal sac compr
ession seen in patients with symptomatic lumbar epidural lipomatosis.
Recognition of this sign will aid with proper diagnosis of this unusua
l disorder. Methods. Computerized Tomography (CT) and Magnetic Resonan
ce Imaging (MRI) examinations of the lumbar spine performed in the eva
luation of low back pain over a 24 mo period demonstrated nine patient
s with excessive fat in the epidural space. Myelography was performed
on five of these patients. Detailed analysis of the shape and degree o
f thecal sac compression was made. Results. Eight of the nine patients
with epidural lipomatosis demonstrated a characteristic type of theca
l sac compression not seen with other spinal disorders. On cross secti
onal imaging, the thecal sac has a striking stellate appearance with t
hree rays emanating from a central core. This produces a trifid shape
resembling the letter ''Y'': In two patients scanned following subsequ
ent surgical removal of the epidural fat, the thecal sac had resumed i
ts normal configuration. Conclusion. A seemingly specific and easily r
ecognized type of compression of the thecal sac may occur with lumbar
epidural lipomatosis. This creates a trifid appearance of the thecal s
ac; we have termed this the ''Y'' sign.