Disc extrusion

Disc extrusion is a type of intervertebral disc herniation and is distinguished from a disc protrusion in that it:

  • in at least one plane, has a broader dome (B) than a neck (A)
    and/or
  • extends above or below the disc level (into the suprapedicular or infrapedicular zone)

Disc extrusions are associated with a defect in the annulus fibrosus which allows herniation of nucleus pulposus beyond the confines of the disc. Depending on imaging method, the distinction between extrusion and protrusion may be difficult, in such cases, the general expression "disc herniation" may be used. 

Extrusion can be in any axial direction and may migrate either superiorly or inferiorly. Terminology

Disc protrusion is distinguished form a disc extrusion in that the base of protruded disc material base is narrower than its 'dome'. Further more this material may extend above or below the disc level. 

Disc sequestration is an extrusion where the disc material migrates and becomes separated from the rest of the herniation.

Note: A number of definitions of what exactly constitutes a disc protrusion have been proposed over the years, and it is important to realise that these differ substantially from one another 1-4.  At the time of writing (August 2016) the most recent and widely used terminology was proposed in 2014 by Fardon et al, and represents a consensus of the North American Spine Society, the American Society of Spine Radiology and the American Society of Neuroradiology 4


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Article Information

rID: 6192
Section: Pathology
Tag: refs
Synonyms or Alternate Spellings:
  • Intervertebral disc extrusion
  • Disc extrusions
  • Intervertebral disc extrusions
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    Figure 1: disc extrusion
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    A focal disc prot...
    Figure 2
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    T2 Axial

Left si...
    Case 1: foraminal disc extrusion : T2
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    Disc extrusion : T2
    Case 2: central disc extrusion : T2
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    Case 3
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    Fig. 1
    Case 4: left lateral extraforaminal extrusion
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    Case 5: left lateral disc extrusion
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    Case 6: left L4/5 disc extrusion with NRE
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    Case 7: left L4 extra-foraminal compression
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    Case 8: at L5/S1 level
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    Case 9
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