Degenerative disc disease (DDD): Normal anatomy of the ...

DEGENERATIVE DISC DISEASE

Prof. Cem ?alli

EDiNR, EDiPNR, EDER

Chief of Neuroradiology Section, Ege University Medical Faculty, Dept of Radiology

Izmir, TURKEY

Degenerative disc disease (DDD):

Normal anatomy of the (intervertebral) disc:

? A component of spinal degeneration

? One of the most common cause of back pain

? Has a high medical / socioeconomic significance

? DDD should not always be interpreted as `'disease''

? Not always correlated with the clinical findings

? Present almost 30% of normal population

? Radiologists should be aware of the imaging findings



Normal anatomy of the (intervertebral) disc:

MRI protocol for lumbar spine?

Cor STIR/T2w/PD

Sag T2w FSE Sag T1w FSE

Nucleus pulposus

End plates

Soft structure Containing ? Water ? proteoglycans ? Collagen type II

T2W hyperintense

Annulus fibrosus

Cartilaginous structure Provides disc nutrition

T2W & T1W hypointense

Strong fibrocartilaginous Attached to the end plates Containing ? Collagen type I ? Dense fibers

T2W & T1W hypointense

Did you know? ? L4-5 disc is the largest avascular space in our body

Axial T2w FSE

Axial T1w FSE

Sag STIR

Disc degeneration: Imaging

Novel techniques: ? T1-rho calculation

? T2/T2* mapping ? CEST ? MRS ? Sodium-MRI ? etc....

All trying to evaluate the chemical composition of the disc, mainly proteoglycan content.

Physiology behind the normal disc

A normal disc maintains an `'Intradiscal pressure'' Degeneration of Nuclues leads to decreased pressure of NP

Kushchayev SV, et al. ABCs of the degenerative spine. Insights Imaging. 2018 Apr;9(2):253-274.

Why does a disc go degeneration?

? Genetic influence ? Aging ? Occupational / Mechanical stress ? Obesity ? Smoking ? Trauma ? Metabolic conditions

Pathophysiology behind the disc degeneration

Burden to the disc

Desiccation of NP

Passing mechanical load to AF

Increased load results in cracks of AF (Fissures / tears)

DDD: What does it include?

1. Disc degeneration

? Desiccation, dehydration, fibrosis, disc space narrowing, bulging, intradiscal gas / vacuum phenomenon

2. Annular fissure / tear

? Concentric, radial, transverse

3. Disc herniation

? Protrusion, extrusion, sequestration, migration

Disc degeneration: Imaging Loss of T2w hyperintensity Loss of disc height Endplate changes

Pfirrman's classification

Disc degeneration: Imaging Pfirrman's classification

Kushchayev SV, et al. ABCs of the degenerative spine. Insights Imaging. 2018 Apr;9(2):253-274. Farshad-Amacker Na et al. MR imaging of degenerative disc disease. EJR. 2015, 1768-1776.

Disc degeneration: Imaging

Modified Pfirrman's classification

Griffith JF, et al. Spine. 2007 32:708-712.

Disc degeneration: Imaging Vacuum phenomenon: Nitrogen gas accumulation in the degenerated disc

Disc degeneration: Imaging

Intradiscal fluid accumulation:

Commonly together with;

Vacuum phenomenon, endplate degenerative changes (Modic type I), ? Mimicks spondylodiscitis !!

Degenerative endplate changes:

? Signal changes

? by Modic et al. (1988)

? Morphological changes

? by Rajasekaran et al. (2008)

Degenerative endplate signal changes:

Modic changes: Can convert to each other / mixed changes

Modic type I

Modic type II

Modic type I `'water''

Modic type II `'fat''

Modic type III `'sclerosis''

Modic type III

Degenerative endplate changes:

Rajasekaran et al. (2008)

Annular fissures / tears:

Fissure of annulus fibrosus May be:

? Concentric ? Radial ? Transverse

Annular fissures / tears:

Hyperintense zone on T2w images (HIZ): Fluid / granulation tissue in AF May not certainly present an Annular fissure or Nucleus!! May show enhancement

Kushchayev SV, et al. ABCs of the degenerative spine. Insights Imaging. 2018 Apr;9(2):253-274.

May be asymptomatic Differentiation between these 3 types challenging on MRI Usually as Hyperintense zone on T2w images (HIZ)

Farshad-Amacker Na et al. MR imaging of degenerative disc disease. EJR. 2015, 1768-1776.

Disc herniation (displacement):

Disc material exceeding the normal margins of the vertebral body Displacement of the part of disc material beyond the limits of disc space

May include materials of: ? Nucleus pulposus ? Annulus fibrosus ? Cartilage ? Fragmented apophyseal bone

X Herniated nucleus pulposus (HNP)

Disc herniation (displacement):

May be diffuse ? Bulging (symmetrical, asymmetrical) May be focal ? Herniation

Disc bulging:

Circumferential disc prolapse >50% of the circumference Mostly less than 3mm. Usuallly the annulus is intact & asymptomatic

25%

Protrusion

Extrusion

25%

Extrusion with sequestration

25%

25%

Symmetrical bulging

Asymmetrical bulging

Disc bulging:

Generalized extension of the disc beyond the edges of the ring apophyses.

Asymmetric disc bulging:

Displacement of the disc material ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download