4. Degenerative change is considered a response to insults - mechanical or
metabolic injury, rather than a disease.
The aetiology of the degenerative changes may be
• Mechanical micro-insults
• Damage secondary to macro-insults, such as
• Spinal fractures
• Spinal surgery not related to degenerative disc disease
• Significant metabolic processes, such as ochondrosis or
mucoplysaccharidoses
5. Approach
The pathophysiology based approach in assessing imaging findings in
the degenerative spine can:
• Accurately characterise the process in the involved segment
• Identify the sequence of degenerative changes and predict further
abnormalities
• Identify hidden or subtle abnormalities based on indirect signs
• Assist clinicians in finding the source of pain or neurological
symptoms
• Identify the best treatment options for patients.
6. The degenerative
process may include
other elements of the
involved functional
spinal unit, which is
termed as horizontal or
segmental
degeneration, or change
the entire biomechanics
of the spine, including
the adjacent functional
spinal units, known as
an adjacent segment
disease.
7. Degenerative changes of the disc
Pathological changes
• Water and proteoglycan content decreases
• Collagen fibers become distorted
• Tears may occur in the lamellae
Results in
• Decreased disc height and volume
8. • X-ray: show spinal degenerative changes
but not a herniated disc; rule out obvious
underlying problems
• CT: Relatively less used
• MRI: Modality of choice
9.
10. DISC BULGE
Generalized or circumferential disc displacement (involving 50% to 100% of the
Bulging can be physiologic (e.g. in the mid-cervical spine and at L5–S1), can re
11. Symmetrical and asymmetrical bulging disc on transverse CT or MRI
scans.
• Normally the intervertebral disc (gray) does not extend beyond the edges of
the ring apophyses (black line).
• In a symmetrically bulging disc, the disc tissue extends concentrically beyond
the edges of the ring apophyses (50%–100% of disc circumference).
• An asymmetrical bulging disc can be associated with scoliosis. Bulging discs
12.
13.
14. ANNULAR TEAR
Disruption of concentric collagenous fibers comprising the
annulus fibrosus
MR Findings
• T1WI: Contrast-enhancing nidus in disc margin
• T2WI: High signal zone at edge of disc which has low intrinsic signal
15.
16. TYPES
Concentric tears are circumferential lesions which are found in the outer layers of the
Radial tears are characterized by an annular tear which permeates from the deep central
Transverse tears, also known as “peripheral tears” or “rim lesions,” are horizontal rupt
18. On a CT discography. The black arrows point to the concentric annular tear in the periphery of the annulus
In Fig. #1 the injected dye (black) does not leak out of the nucleus. This is normal. Fig.#2 demonstrates a m
19. DISC HERNIATION
Herniation is defined as a localized displacement of disc material (nucleus, cartil
• Intravertebral Herniations
• Protruded Disc
• Extruded Disc
20.
21.
22. INTRAVERTEBRAL HERNIATIONS
Herniated discs in the cranio-caudal (vertical) direction through a break in one or both
Nutrient vascular canals may leave scars in the endplates, which are weak spots repre
23.
24.
25. PROTRUDED DISCThe terminology “protruded disc” is used when the base of the
disc is broader than any other diameter of the displaced
material.
Based on a two-dimensional assessment of the disc contour in
the transverse plane, a protruded disc can be focal (involving
<25% of the disc circumference) or broad-based (involving
25%–50% of the disc circumference).
26. Types of disc herniation as seen on transverse CT or MRI scans.
Protrusions: the base of the herniated disc material is broader than t
27.
28. EXTRUDED DISC HERNIATIONS
The terminology “extruded disc” is used for a focal disc extension of
Extrusion: the base of the herniation is narrower than the apex (toothpaste sign)
29. Massive lumbar disc extrusion at L5–S1 Sagittal and axial T2WI. The extrude
Extrusion is also used when there is no continuity between the herniated disc m
30. If the displaced disc material has no
connection with the parent disc, it is
called a “sequestrated fragment”.
This is synonymous with a “free
fragment”.
31. MIGRATION – SEQUESTRATION
Migration
Indicates displacement of disc material away from the site of extrusion, regardless of whether seq
Sequestration
Indicate that the displaced disc material has lost completely any continuity with the parent disc
32. A Small subligamentous herniation (protrusion) without significant disk material migration.
B Subligamentous herniation with downward migration of disk material under the PLL.
C Sub-ligamentous herniation with downward migration of disk material and sequestered fragment.
33.
34. Three degenerative stages of vertebral endplates and subchondral bone
(Modic et al. 1988a,b)
Vertebral Endplates and Bone Marrow
Changes
35.
36.
37.
38.
39.
40.
41.
42.
43. Degenerative Changes of the
Posterior Elements1. Facet Joints
2. Ligamentum Flavum
3. Spinal Canal
4. Spinous Process
5. Nerve root
45. Degenerative changes of the facet jointDegenerative Changes
Cartilage lining loses water
content
Cartilage wears away
Facets override each
other
Leads to abnormal
function of motion segment
46. Arthropathy of the Facet Joints
Osteophytes - narrow the lateral recesses and intervertebral foramina
causing central or lateral spinal canal stenosis.
Hypertrophy - enlargement of an articular process with normal
proportions of its medullary cavity and cortex.
More subtle changes like cartilage changes, joint space narrowing and
subchondral erosions can be better analysed on axial CT and MR
imaging.
CT is superior to MR imaging in the depiction of joint space narrowing
and subchondral sclerosis.
57. Degenerative Changes of Ligamentum Flavum
Partial ruptures, necrosis and calcifications - Negatively impact function
Chronic degenerative changes in the ligamentum flavum, followed by (re
58. MRI of spinal stenosis: arrow points to the moderately stenotic spinal canal caused by hypertrophic fac
59.
60.
61.
62. LIGAMENTUM FLAVUM HYPERTROPHY
Symmetrical thickening of the ligamentum flavam is a frequently observed find
Calcifications of the ligamentum flavam have been observed in patients with d
Calcifications are also associated with metabolic diseases such as renal failure,
63.
64. Wildermuth S et al (1998) Lumbar spine: quantitative and
qualitative assessment of positional (upright flexion and
extension) MR imaging and myelography. Radiology
207(2):391–398
