DEGENERATIVE DISC DISEASE Prof. Cem Çallı EDiNR, EDiPNR, EDER Chief of Neuroradiology Section, Ege University Medical Faculty, Dept of Radiology Izmir, TURKEY Degenerative disc disease (DDD): • 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: http://www.southcoastspine.com.au/the-spine-basic-anatomy-and-mechanics Normal anatomy of the (intervertebral) disc: Nucleus pulposus Soft structure Containing • Water • proteoglycans • Collagen type II T2W hyperintense Annulus fibrosus Strong fibrocartilaginous Attached to the end plates Containing • Collagen type I • Dense fibers T2W & T1W hypointense End plates Cartilaginous structure Provides disc nutrition T2W & T1W hypointense Did you know? Î L4-5 disc is the largest avascular space in our body MRI protocol for lumbar spine? Cor STIR/T2w/PD Sag T2w FSE Sag T1w FSE Sag STIR Axial T2w FSE Axial T1w FSE Disc degeneration: Imaging Novel techniques: ¾ T1-rho calculation ¾ T2/T2* mapping ¾ CEST ¾ MRS ¾ Sodium-MRI ¾ etc…. All trying to evaluate the chemical composition of the disc, mainly proteoglycan content. Physiology behind the normal disc Kushchayev SV, et al. ABCs of the degenerative spine. Insights Imaging. 2018 Apr;9(2):253-274. A normal disc maintains an ‘’Intradiscal pressure’’ Degeneration of Nuclues leads to decreased pressure of NP Why does a disc go degeneration? ¾ Genetic influence ¾ Aging ¾ Occupational / Mechanical stress ¾ Obesity ¾ Smoking ¾ Trauma ¾ 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 ¾ Desiccation, dehydration, fibrosis, disc space narrowing, bulging, intradiscal gas / vacuum phenomenon 2. Annular fissure / tear ¾ Concentric, radial, transverse 3. Disc herniation ¾ 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.
Transcript
DEGENERATIVE DISC DISEASE
Prof. Cem ÇallıEDiNR, EDiPNR, EDER
Chief of Neuroradiology Section,Ege University Medical Faculty, Dept of Radiology
Izmir, TURKEY
Degenerative disc disease (DDD):
• 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
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: ImagingModified Pfirrman’s classification Griffith JF, et al.
Spine. 2007 32:708-712.
Disc degeneration: Imaging
Vacuum phenomenon:
Nitrogen gas accumulation in the degenerated disc
Intradiscal fluid accumulation:Commonly together with;Vacuum phenomenon, endplate degenerative changes (Modic type I),
Mimicks spondylodiscitis !!
Disc degeneration: Imaging
Degenerative endplate changes:
Signal changesby Modic et al. (1988)
Morphological changesby Rajasekaran et al. (2008)
Degenerative endplate signal changes:
Modic type I
‘’water’’
Modic type II
‘’fat’’Modic type III
‘’sclerosis’’
Modic changes:
Can convert to each other / mixed changes
Modic type I
Modic type II
Modic type III
Degenerative endplate changes:
Rajasekaran et al. (2008)
Kushchayev SV, et al. ABCs of the degenerative spine. Insights Imaging. 2018 Apr;9(2):253-274.
Annular fissures / tears:
Fissure of annulus fibrosus
May be:
Concentric
Radial
Transverse
Farshad-Amacker Na et al. MR imaging of degenerative disc disease. EJR. 2015, 1768-1776.
May be asymptomatic
Differentiation between these 3 types challenging on MRI
Usually as Hyperintense zone on T2w images (HIZ)
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
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
Herniated nucleus pulposus(HNP)X
Disc herniation (displacement):
May be diffuse Bulging (symmetrical, asymmetrical)
May be focal Herniation
Protrusion Extrusion Extrusion with sequestration
Disc bulging:
Circumferential disc prolapse >50% of the circumference
Mostly less than 3mm.
Usuallly the annulus is intact & asymptomatic
25%
25%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 <50% circumference
of the disc
Asymmetric disc bulging:
Disc protrusion:
Displacement of the disc material <50% circumference
of the disc.
Focal <25% of disc circumference
Broad-based 25-50% of disc circumference
Some fibers of annulus / PLL intact
The distance beetween the edges of the base / neck of disc
material > the distance between the edges of herniated disc
Disc protrusion:
Focal disc protrusion Broad based disc protrusion
Disc protrusion:
Focal disc protrusion
Disc protrusion: Disc extrusion:The distance beetween the edges of the base / neck of disc material < the distance between the edges of herniated discFull thickness disruption of annulus.
L4-5 protrusion L5-S1 extrusion
Disc extrusion:
S1 nerves
Disc extrusion: Disc extrusion with sequestration :Extruded disc material that has no continuity with the disc of
origin / parent disc.
Disc sequestration :Disc sequestration may migrate in caudal or cranial direction
Disc sequestration (Containment):Subligamentous
‘’Contained’’
Transligamentous (PLL disrupted)
‘’Uncontained’’
Disc sequestration:
L4-5 right disc sequestration, inferior migration,
L5 nerve root compression & nerve root edema
Sequestrated disc material hyperintense.
Intravertebral herniaton:
Schmorl node
Disc herniation: Location
Farshad-Amacker Na et al. MR imaging of degenerative disc disease. EJR. 2015, 1768-1776.
Disc herniation: LocationCentral / median
Paracentral / left-right central
Foraminal
Extraforaminal / Far lateral
Anterior
Disc protrusion: Location
Central Right ParacentralRight central
Left foraminal Right extraforaminal
Degree of disc herniation:
Mysliwiec LW et al. MSU Classification for herniated lumbar discs on MRI: toward developing objective criteria for surgical selection. Eur Spine J. 2010 Jul; 19(7): 1087–1093.
