CT myelography for differential diagnosis between intramedullary and intradural-extramedullary spinal tumors in the region of the conus medullaris.
We reviewed the myelograms and computed tomographic myelograms of 12 cases of intraspinal tumor with a "cupping sign" on the myelogram in the region of the conus medullaris from 1986 to 1988. There were 5 intramedullary tumors, 4 of them having an exophytic component, and 7 intradural-extramedullary tumors. The myelograms revealed that 4 of the 5 intramedullary tumors showed expansion and the outline of the conus medullaris was irregular, whereas 1 of the tumors showed smooth compression (crescent-shaped) and displacement of the conus medullaris. Six of the 7 intradural-extramedullary tumors showed smooth compression and displacement of the conus medullaris, while 1 of the tumors had caused expansion of the conus medullaris. Complete blockage of the passage of the contrast medium was noted in 3 of the 5 intramedullary tumors, while a partial block was noted in 3 of the 7 intradural-extramedullary tumors. Two of the 7 intradural-extramedulllary tumors showed an extradural tumor component, such as a dumb-bell tumor and a enlarged intervertebral neural foramen. Tumor calcification was noted in 1 of the 7 intradural-extramedullary tumors. Dural ectasia was noted in 2 of the 7 intradural-extramedullary tumors which were later proven to be neurofibromatosis. We conclude that smooth compression (crescent-shaped) and displacement of the conus medullaris, existence of an extradural tumor component, and eroded intervertebral neural foramina favor intradural-extramedullary tumors, while expansion and a conus medullaris with an irregular outline favors intramedullary tumors.
Department of Radiology, Medical College and Hospital, National Taiwan University, Taipei, R.O.C.
T C
TC
Wang
K M
KM
Huang
H M
HM
Liu
Y C
YC
Chang
C Y
CY
Hsu
D000293:Adolescent; D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000000981:diagnostic imaging; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000000981:diagnostic imaging*; D008875:Middle Aged; D009192:Myelography; D009442:Neurilemmoma / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D013120:Spinal Cord Neoplasms / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed