DISC PROLAPSE AND DEGENERATIVE CHANGES

Intervertebral DiscsIntervertebral Discs

Gel like Tissue between Gel like Tissue between each vertebraeach vertebra

fibro cartilaginous fibro cartilaginous cushionscushions serve as the spine's shock serve as the spine's shock

absorbing systemabsorbing system protect the vertebrae, brain, protect the vertebrae, brain,

and other structuresand other structures The discs allow some The discs allow some

vertebral motion extension vertebral motion extension and flexion. and flexion.

Intervertebral DiscsIntervertebral Discs

The disc is made up of The disc is made up of 3 structures the 3 structures the

(1) Nucleus pulposus, (1) Nucleus pulposus, gelatinous centergelatinous center

(2) Annulus Fibrosus. (2) Annulus Fibrosus. Its job is to contain the Its job is to contain the nucleusnucleus

(3) Vertebral end plates (3) Vertebral end plates that attach the disc to that attach the disc to the vertebrae the vertebrae

Process of wear and tear of intervertebral discs, vertebral bodies, and facet joints is called spondylosis

Commonest cause of entrapment spinal neuropathy

Usual age group >60 yrs

Usually asymptomatic

DISC PROLAPSE

Extrusion of nucleus pulposus through posterior or posteriolateral radial tear in annulus fibrosis

TYPES

Focal herniation is a herniated disc less than 90° of the disc circumference.

Broadbased herniation is a herniated disc in between 90°-180° of the disc circumference.

Bulging Disc is the presence of disc tissue 'circumferentially' (180°-360°) beyond the edges of the ring apophyses and is not considered a form of herniation

AXIAL LOCALISATION OF HERNIATED DISCS

Central or medial posterior longitudinal ligament is thickest in this region,disc usually herniates slightly to the left or right of this central zone.

Paramedian or lateral recess PLL is not as thick in this region, this is common region for disc herniations.

Foraminal or subarticular It is rare for a disc to herniate into the intervertebral foramen.'Dorsal Root Ganglion' lies in this zone resulting in severe pain, sciatica and nerve cell damage.

Extraforaminal or lateral Disc herniations in this region are uncommon.

IMAGING for disc prolapse

CT SCAN

Disc material is denser than CSF in thecal sac…… so clearly seen against epidural fat

BUT, very large extrusion may be missed.

MRI

Extruded fragments brighter on T2

Enhance after contrast

Sometimes heavily calcified

More reliable in cervical spine where there is less epidural fat

X-RAYS

Non specific findingsReduction of disc space or vertebral mal alignment or normal

Axial T1-weighted image shows protrusion of a left paracentral disc with compression of left S1 root

Axial T2-weighted image shows protraction of a left paracentral disc with compression of left S1 root

CT axial.L3,4 disc space. Soft tissue mass in R. posterolateral aspect of disc encroaching into intervertebral foramen and extending lateral to it.arrow…L3 N

T1W axial. L4,5 disc, disc fragment extends behind upper part of right side of body of sacrum. Displacing 1st sacral nerve root post and erodes sacral body.

L5/S1 disc space.low signal mass protruding posteriorly and to the right from the posterior disc margin.This causes only minor compresion on the anterior margin of the theca (the bright, CSF containing sac in the spinal canal). The nerve roots within the theca are visible around its posterolateral margins and are not affected. However the neural foramen on the right is obliterated - compare with the other side where the higher signal fat, and the lower signal S1 nerve root are clearly seen

Sagittal T2 weighted MRI images of 49-year male with history of radiculopathy. a. Pre-op image showing disc prolapse at C5/6 level. b,c,d are post-op images

MRI of a patient showing disc prolapse between L5 and S1 vertebra

DEGENERATIVE CHANGES

osteophytosis & marginal sclerosis

Mostly in lower cervical and lumbar region

reactive changes Degeneration in ligaments

ossification

calcification

these changes occur in

post. longitudinal ligament

cruciform ligament

ligamenta flava

capsular ligament of facet joints

Also include Ossification of post. long. Ligament

Retro-odontoid pseudotumor

Ossification of ligamentum flavum

Synovial cysts

degenerative changes are seen in

Ochronosis

Charcot spine

Ankylosing spondylitis

Rheumatoid arthritis

Isolated phenomenon

X-RAYS

most of the features of degeneration can be seen

If, sagittal diameter of spinal canal in cervical region <10mm…..spinal cord compressed

CT SCAN / MRI

Deformation of spinal & intervertebral canals…CT / MRI

Better visualization of neural structures… MRI

Differentiation from infection….MRI… absent/ non-uniform high signal, irregularity/fragmentation.

Sagittal T2W contrast.ossification of post. Longitudnal ligament

SPINAL STENOSIS

Most common in

Achondroplasia

Acromegaly

CT / MRI

Spinal canal is very narrow

Cross-sectional area less than 110mm²

No CSF signal on T2 weighted image

Reduntant coiling of intradural roots above stenosis…on MRI… entrapment of cauda equina

Sagittal T2W ,with contrast. Stenosis of spinal canal at L4,5. no CSF signal at stenosis

POST-OPERATIVE CHANGES Post-op recurrent myelopathy / radiculopathy

2 types

Discogenic

Reactive

CT / MRI

Discogenic Typical mass continuous with disc substance

Reactive Contracting lesion standing around theca / nerve root,

continuing into soft tissue.

T2W, disc higher signal than scar

Recent scar enhances faster, old scar less and slowly.

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