Intervertebral disc disease nomenclature has changed over the years, and familiarity with definitions is essential if clear communication is to be achieved via radiology reports or referrals, especially as lumbar disc disease is a common problem and a source of a great deal of imaging. Terms such as bulge, protrusion, extrusion, sequestration, and migration all have specific meanings although their definition varies from publication to publication.
The 2014 recommendation - "Lumbar disc nomenclature: version 2.0" - from The American Society of Spine Radiology, The American Society of Neuroradiology, and The American Spine Society has been widely accepted, and are used in this, and related articles 3,4.
Terminology
Disc
The following terms relating to intervertebral discs are recognized 3. A brief description is included for some; each is then discussed in more detail in separate articles.
-
disc bulge: annular tissue projects beyond the margins of the adjacent vertebral bodies, involves >90° of circumference
circumferential bulge: involves the entire disc circumference
asymmetric bulge: does not involve the entire disc circumference
-
protrusion: focal herniation of disc material beyond the margins of the adjacent vertebral body, involves <90° of the disc circumference, with a base that is wider than the dome
extrusion: focal herniation of disc nuclear material through an annular defect, remaining in continuity with the disc, with a base narrower than the dome of the extrusion
sequestration: distal migration of extruded disc material away from the disc, with no direct continuation with the adjacent disc
pseudodisc of anterolisthesis: deformity of annular fibers due to anterolisthesis mimicking a true protrusion or bulge
Localization
In the case of disc herniation then the abnormally displaced nucleus pulposus should be described in terms of its position in both axial and sagittal planes.
Axial localization
Disc herniations are localized in the axial plane into several zones:
central: including paracentral (more precisely, right central or left central)
subarticular: including lateral recess (subarticular zone at the pedicular level)
foraminal: also known as lateral (non-standard)
extraforaminal: also known as lateral (non-standard) or far lateral
anterior
Sagittal localization
The pedicle and disc are used as reference points for craniocaudal localization on sagittal images:
disc level: confined to between the vertebral endplates
suprapedicular: between the superior endplate and the superior border of the pedicle
pedicular: at the level of the pedicle
infrapedicular: below the lower margin of the pedicle to the inferior endplate
Volume
Simple method to grade 3 spinal canal (from axial sections) or neural foraminal (from axial or sagittal sections) compromise:
mild: less than 1/3 of the spinal canal or nerve root foramen diameter
moderate: between 1/3 and 2/3 of the spinal canal or nerve root foramen diameter
severe: greater than 2/3 of the spinal canal or nerve root foramen diameter
Unable to process the form. Check for errors and try again.