What is the typical age of a person suffering from degenerative disease of the
intervertebral disc?
Is commonest in adults (especially >50 years).
Uncommon in the very young;
Uncommon in the very old.
Which is the commonest site of disc degeneration?
Lx region especially L4-L5 and L5/S1
Briefly outline the pathological events occurring as the intervertebral disc degenerates.
- With normal ageing the I/V disc gradually changes → fissures and herniations.
- Reactive bone formation → Schmorl’s Nodes
- Flattening of the IVD
- Collapse of the disc space → Facet Displacement → OA
- Severe OA may result in → stenosis & osteophytic growth
- Fibrocartilage replacement & segmental fibrosis
- Segmental fibrosis → stabilisation → decrease in associated backpain.
List the possible sources of pain emanating from a focus of chronic disc degeneration.
- Facet joint misalignment
- Facet joint arthritis
- Vertebral instability
- Root canal stenosis
- Spinal canal stenosis
- Sensory nerves in the annulus fibrosus
- Posterior longitudinal ligament tension & ossification
List the typical radiological manifestations that accompany chronic disc degeneration.
Increased osteophyte production Narrowing of spinal canal Narrowing of IV foramina Nucleus pulposus becomes fibrocartilage FIBROSIS of affected structures
List two causes of acute disc herniation.
- jarring-strain (Cx spine)
- combined flexion/compression of the vertebral column (Lx Spine)
- sudden straining when the vertebral column is in an unstable position (Lx Spine)
Does acute disc herniation occur in normal intervertebral discs?
No, physical stress does not commonly cause acute disc herniation in normal discs → acute disc prolapse mostly results when excessive stress is placed on an abnormal disc.
Briefly outline the pathological events occurring during acute disc herniation. Where possible, present the events in the order in which they normally occur.
a. partial herniation:
b. posterolateral rupture
c. large central herniation
d. complete herniation:
Discuss the relative frequency of acute disc herniation in the various parts of the vertebral column.
- lumbosacral discs ie L4-5 and L5-S1
- cervical discs ie C5-C6 and C6-C7
- thoracic discs
Is the clinical picture identical in all cases of acute disc herniation? Discuss.
No → great variation in rate of onset, extent, and variety of symptoms and signs.
Herniation of the nucleus pulposus is not an instantaneous event. It occurs in 3 stages, each of which requires some time in order to occur:
- initial injury ie annulus fibrosus is torn/damaged. The injury may not progress beyond this stage.
- bulging of the nucleus pulposus against the posterior ligament ie acute back pain stage. The injury may not progress beyond this stage.
- herniation of nucleus pulposus through the posterior ligament results in impingement against nerves: ie radiating limb pain stage
Which imaging modalities are usually employed in the diagnosis of acute disc herniation?
- XR
- CT
- MRI
- Myelography
Which is the most widely used imaging modality?
- XR/ CT
List 6 causes of lower back and lower limb pain
- vascular occlusion
- intrapelvic mass
- arthritis of hip
- OA
- AS
- tumours of the cord/cauda equina
- tumours of the vertebrae
- TB of spine
- spondylolisthesis
- prolapsed I/V disc
- tumour of ilium/sacrum
List 6 causes of neck and upper limb pain.
- cord tumours
- prolapsed cervical disc
- cervical OA
- vertebral tumours
- nerve root tumours
- thoracic inlet tumours
- cervical rib
Describe Acute Partial Herniation.
a. partial herniation.
- fibrocartilaginous material (ie the nucleus pulposus) is extruded (bulges) posteriorly
- the annulus usually bulges to one side of the posterior longitudinal ligament
- the degree of the partial herniation gradually increases with successive injuries
Describe Acute Posterolateral Rupture.
b. posterolateral rupture
- may press on the nerve root proximal to its point of exit through the I/V foramen
- L4/5 herniation causes compression of 5th lumbar root
- L5/S1 herniation causes compression of 1st sacral root
Describe Central Herniation.
c. large central herniation
- ie herniation of both the capsule (annulus fibrosus) and the nucleus pulposus
- may result in compression of the spinal cord or cauda equina
Describe Complete Herniation.
d. complete herniation.
part of the nucleus may:
- break loose and lie free in the spinal canal
- break loose and work its way into the intervertebral foramen
Describe Chronic Disc Changes and Reactive Bone Formation.
With normal ageing the I/V disc gradually changes →
- annulus fibrosus develops fissures parallel to the vertebral endplates
- small herniations of nuclear material squeeze through the annulus in all directions
In time these herniations result in reactive bone formation around Schmorl’s nodes and other sites of herniations (vertebral margins).
Describe Chronic Disc Spondylosis & OA Development.
These changes result in: flattening of the I/V disc ie “spondylosis” osteophyte formation
Collapse of the disc space results in displacement of the facet joints which results in osteoarthritis after many months and years.
Severe OA may result in →
- narrowing of spinal canal and I/V foramen
- increased osteophyte formation
- spinal stenosis
Describe advanced stages of Chronic Disc Herniation.
By the end of the degenerative process we observe the following:
- total replacement of the gelatinous mucoid material of the nucleus pulposus with fibrocartilage
- segmental fibrosis
Segmental fibrosis often results in stabilisation of the disc lesion and a decrease in associated backpain.
