1. Degenerative Diseases of spine
DR. NITIN WADHWANI
Prof. and H.O.D department of Radio-diagnosis,
DY Patil medical college, hospital & research institute Kolhapur
2.
3. Functional spinal unit (FSU)
70% of applied axial compression is transmitted by the vertebral body and the intervertebral discs
30% of the load being distributed through the facet joints
4. TYPES OF SPINAL DEGENERATION
Horizontal degeneration.
Adjacent segment disease
7. A disc bulge represents displacement of the outer fibers of the annulus
fibrosus beyond the margins of the adjacent vertebral bodies, involving more than
one-quarter (25% or 90°degrees) of the circumference of an intervertebral disc .
DISC BULGE
8.
9. Disc protrusions are a type of disc herniation characterized by protrusion of disc content
beyond the normal confines of the intervertebral disc, over a segment less than 25% of
the circumference of the disc.
• The width of the base is wider than the largest diameter of the disc material which
projects beyond the normal disc margins.
• The protrusion must not extend above or below the relevant vertebral endplates .
A disc protrusion is also described in terms of its axial position, into
• central,
• subarticular,
• foraminal,
• extraforaminal,
• anterior locations.
DISC PROTRUSION
11. 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)
• 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.
DISC EXTRUSION
12. Left sided L3/4 foraminal disc extrusion compressing only the exiting L3 nerve root.
Axial T2
Sagittal T2
13. DISC PROTRUSION
when the base of the disc
is broader than any other
diameter of the displaced
material.
DISC EXTRUSION
focal disc extension of which
the base against the parent disc
is narrower than the diameter of
the extruded disc material,
measured in the same plane.
14. MIGRATION-SEQUESTRATION
Migration
indicates displacement of disc material away from the
site of extrusion, regardless of whether sequestrated or not.
• Sequestration
indicate that the displaced disc material has lost completely
any continuity with the parent disc.
15. A - Small subligamentous herniation (protrusion) without significant disk material migration.(disc protrusion)
B - Subligamentous herniation with downward migration of disk material under the PLLC.(disc extrusion)
C - Sub-ligamentous herniation with downward migration of disk material and sequestered fragment (arrow).
16. Degenerative bone marrow (Modic) changes. (a–c) Type 1 changes. (d–f) Type 2 changes. (g–i) Type 3
changes
Marrow edema Fatty degeneration Bony sclerosis
END PLATE CHANGES
17. Disc desiccation (also known as disc dehydration) is an extremely common degenerative change of
intervertebral discs.
It results from replacement of the hydrophilic glycosaminoglycans within the nucleus pulposus with
fibrocartilage.
Although it is commonly thought that the resultant loss of disc height is due to reduction in nucleus pulposus
volume, this has been shown not to be the case. Rather disc height loss is a result of annular bulging and
vertebral endplate bowing.
DISC DESICCATION
18. A grading system of intervertebral disk degeneration
CHANGES IN NUCLEOUS PULPOSUS
21. Annular fissures, also known as annular tears, are a degenerative deficiency of one or more layers that make up
the annulus fibrosus of the intervertebral disc.
Pathology
As we age, the ability of the annulus to contain the pressurized nucleus will become compromised
secondary to a drying and weakening phenomenon (called degenerative disc disease) that occurs in all discs.
As a result, the nucleus may rip its way through the annulus and cause an annular tear.
ANNULAR FISSURES
23. INTRAVERTEBRAL HERNIATIONS
• Herniated discs in the cranio - caudal (vertical) direction through a break in one or
both of the vertebral body endplates are referred to as "intravertebral herniations"
also known as Schmorl's nodes
• They are often surrounded by reactive bone marrow changes.
• Nutrient vascular canals may leave scars in the endplates, which are weak spots
representing a route for the early formation of intrabody nuclear herniations.
25. Degenerative changes in the facet joints
• Facet joint arthropathy (also known as facet joint
arthrosis) is a common cause of low back pain and
is most commonly due to osteoarthritis.
• It occurs from facet joint chondral loss, osteophyte
formation and hypertrophy of the articular
processes that may cause spinal canal stenosis in
severe cases.
26. The ligamentum flavum, called the yellow ligament because of the high content of yellow elastin, makes up about
60–70% of the extracellular matrix.
Ligamentum flavum hypertrophy refers to abnormal thickening of the ligamentum flavum. If severe, it can be
associated with spinal canal stenosis.
Ligamentum flavum hypertrophy
27. A classification of lumbar degenerative spondylolisthesis
Lumbar spondylolisthesis
Spondylolisthesis (plural: spondylolistheses) denotes the slippage of one vertebra
relative to the one below.
28. Spondylosis
Spondylosis is common nonspecific term used to describe
hypertrophic changes of the end plates (osteophytes) and facet
joints
30. For the evaluation of the spinal canal, stenosis is compatible with an AP diameter of the canal less than 10
mm in the cervical spine or 12 mm in the lumbar spine
31. grading of severity of central, lateral and foraminal stenosis on the lumbar spine
Notas do Editor
Two adjacent vertebrae, the intervertebral disc, spinal ligaments and facet joints between them constitute a functional spinal unit
Types of spinal degeneration.
(a–b) Horizontal degeneration. Initial degeneration of the intervertebral disc (a) subsequently leads to the facet joint osteoarthritis (b).
(c–d) Adjacent segment disease. Severe degenerative changes on a segment result in abnormalities in the level above
Displacement of disc material beyond the limits of the intervertebral disc space may be diffuse (bulging) or focal herniation (protrusion, extrusion and extrusion with sequestration) [21] (Fig. 9). On the axial plane, it may be anterior or posterior.
Focal disc migration (disc herniation) is defined as a condition where a detached piece of the nucleous pulposus migrates from its original intradiscal location. Herniation usually occurs in relatively young patients when intradiscal pressure remains high. Depending on the extent of the focal migration of the nucleous pulposus, disc herniation may result in protrusion, extrusion or sequestration of the nucleous pulposus material. Disc herniation may occur in any direction
Classification
Bulges are always broad, and can be further divided according to how much of the circumference they involve:
circumferential bulge: involves the entire disc circumference
asymmetric bulge: does not involve the entire circumference, but nonetheless more than 90°degrees.
Figure 2a is a normal looking T2-weighted axial MRI image of an L3 disc from a middle-aged male. Note the concave posterior appearance of the disc (arrows).
Figure 2b, which is also a T2-weighted axial image of an L3 disc in another middle-aged male, clearly demonstrates that the posterior disc has lost its normal concavity and is "bulging out" in a smooth and general fashion.
That's it! It's really not so difficult to see a bulging disc.
Difference-
Disc bulge is distinguished from a disc protrusion in that it involves more than 25% of the circumference.
Disc extrusion is distinguished from a disc protrusion in that the base of the protruded disc material is narrower than its 'dome'. Furthermore, this material may extend above or below the disc level.
image 1; Focal disc protrusion compressing traversing S1 nerve root on the left
imge 2:Single T2 image demonstrates a central disc protrusion largely effacing the thecal sac
Terminology
disc protrusion is distinguished from a disc extrusion in that the base of protruded disc material is wider than its 'dome'; furthermore, this protruded disc material must not 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.
Sequestrated disc, also referred to as a free disc fragment, corresponds to extruded disc material that has no continuity with the parent disc and is displaced away from the site of extrusion.
By definition, it corresponds to a subtype of disc extrusion.
The term "migrated" disc refers only to position and not to the continuity of disc substance. So, this term can be used when referring either to extruded discs that still have continuity or those without, i.e. sequestrated (e.g. disc extrusion migrated caudally, sequestrated disc migrated cranially).
Type 1 changes (decreased signal intensity on T1-WI and increased signal intensity on T2-WI, enhancement after contrast administration) correspond to bone marrow oedema and vascularised fibrous tissues
Type 2 changes (increased on T1-WI and iso/hyperintense on T2-WI without contrast enhancement) reflect the presence of yellow marrow in the vertebral bodies (Fig. 17d–f).
Type 3 changes (decreased on both T1- and T2-WI) represent dense woven bone and the absence of marrow. These changes are potentially stable and almost always asymptomatic
Figure #1: Here is the classic presentation of DDD as seen in this T2-weighted sagittal (lateral) image. Note the bright white and healthy L3 disc (above the L4 vertebra) in comparison to the 'black' and desiccated L4 and L5 disc. Also note a 4mm herniation at the L4 disc (between L4 and L5 vertebrae) and a 9mm herniation at the L5 disc. Also note there is a loss of disc height at both L4 and L5, in comparison to the thicker L3 disc.
(a). The vacuum phenomenon. This sagittal CT reformatting image shows the foci of air within the L2–L3 and L3–L4 discs (arrows).
(b) Intradiscal fluid accumulation (arrow).
(c) A sagittal reformatting CT image at the level of C3–C4 shows disc calcification (arrow)
Annulus fibrous fissures: (a–b) Circumferential fissures. A drawing and an axial T2-WI scan at L4–L5 (arrow) showing a rupture of the transverse fibres without disruption of the longitudinal fibres representing circumferential fissures. (c–d) Radial fissures. A drawing and a sagittal CT discogram at L5–S1 showing (arrow) radial fissures extending from the periphery of the annulus to the nucleus, with disruption of the longitudinal fibres. (e-f) Peripheral rim fissures. A drawing and a sagittal T2-WI scan at L5–S1 demonstrating disruptions of Sharpey’s fibres at the annular periphery
image1:Schmorl nodes are noted at the inferior endplates of L3 and L4.
image:2 Herniation of disc material into the superior endplate of L1 with marked surrounding bone marrow edema but no involvement of the T12 endplate and no disc desiccation or edema.
imae 2;V
Ligamentum flavum. (a) A drawing of the normal anatomy of the ligamentum flavum. (b) Normal ligamentum flavum (arrows) on axial T2-WI scans. (c) Severe hypertrophy of the ligamentum flavum on sagittal T2-WI (arrows). Note that there is fluid in the right facet joint, suggestive of segmental instability
A commonly used method of grading spondylolisthesis is the Meyerding classification, which is based on the ratio of the overhanging part of the superior vertebral body to the anteroposterior length of the adjacent inferior vertebral body
traction osteophytes (Fig. 23a) are 2–3-mm bony structures projecting in a horizontal direction, while claw osteophytes (Fig. 23b) have a sweeping configuration toward the corresponding part of the vertebral body opposite the disc.
A wraparound bumper (Fig. 23c) develops along the capsular insertion of the facet joints and is believed to be associated with instability [45].
Spinal canal. (a) Normal spinal canal. The central portion of the spinal canal is bordered laterally by a lateral recess, dorsally by a vertebral arch and ventrally by a vertebral body and discs. The lateral recess is bordered laterally by a pedicle, dorsally by a superior articular facet and ventrally by a vertebral body and discs. The foraminal space is bordered by cephalad and caudal pedicles and facet joints dorsally and a vertebral body and discs ventrally. The extraforaminal space is lateral to the neuroforamen. (b) Spinal canal stenosis. There are four major causes of degenerative spinal canal stenosis: disc herniation, hypertrophic facet joint osteoarthrosis, ligamentum flavum hypertrophy and degenerative spondylolisthesis
Two 32-year-old patients, one asymptomatic (a and b) and the other (c and d) with chronic low back pain and clinical signs of neurogenic claudication. (a and b) Sagittal magnetic resonance images, T2- and T1-weighted, of a patient with normal values of the amplitude of the spinal canal. (c and d) Sagittal magnetic resonance images, T2- and T1-weighted, of a patient with congenital stenosis of the spinal canal, early degenerative changes, with chronic low back pain and clinical signs of neurogenic claudication. In the last case, all sagittal diameters, except at the level of L5 and S1, are markedly reduced and the severity of the stenosis can be quantitatively defined at each level between L1 and L4.
Lumbar lateral canal stenosis can be classified as: grade 0, no stenosis; grade 1, mild stenosis, where there is narrowing of the lateral recess without root flattening or compression; grade 2, moderate stenosis, where further narrowing of the lateral recess occurs with root flattening but there is some preservation of the space lateral to the root in the lateral recess; grade 3, severe stenosis in which there is severe root compression with severe narrowing and complete obliteration of the CSF space surrounding or lateral to the nerve root (Fig. 29) [63].
Lumbar foraminal stenosis can be absent (grade 0), mild (grade 1, with deformity of the epidural fat while the remaining fat still completely surrounds the existing nerve root), moderate (grade 2, with marked foraminal stenosis where epidural fat only partially surrounds the nerve root) and severe (grade 3 or advanced stenosis, with complete obliteration of the foraminal epidural fat) (Fig. 29) [64].