Schmorl’s nodes (SN) or Intervertebral Disc Herniations are Commonly observed on routine radiographs at autopsy. This is a teaching lecture given by Prof. Dr. Mohamed Mohi Eldin, professor of neurosurgery, in the weekly conference of kasr El Aini Neurosurgery Department, Cairo University, November 2010.

1. Spine Study Archives
MMoohhaammeedd MMoohhii EEllddiinn , MB-BCH ,
M.Sc., MD
Professor of Neurosurgery
Faculty of Medicine
Cairo University
EGYPT
Weekly Neurosurgical Conference – Kasr El Aini, 25 November 2010

2. Spine Study Archives
Schmorl’s nodes (SN)
(Intervertebral Disc Herniation)

3. Schmorl’s nodes (SN)
• Commonly observed
– on routine radiographs
– at autopsy
• Represent herniation of the nucleus
pulposus into the adjacent end plate.
• Forms a defect in the upper or lower
surface of the involved vertebra.
• Tend to occur near the central or
posterior axis.
• SN are also a common radiographic
feature of
– Scheuermann’s disease
– Chondrodysplasias such as multiple
epiphyseal dysplasia.

4. Intervertebral Herniation
• The EP has less
resistance to expansile
pressure of nucleous
pulposus than the
normal annulus fibrosus
• Disc herniation in the
craniocaudal direction,
through a defect or
break in the VEP

5. EP Defects can be
• Developmental (intrinsic abnormality of EP)
– Previous vascular channels
– Ossification gaps
– Small indentation defects left during the
regression of chorda dorsalis (notochord)
• Weakening of EP (numerous local and
systemic)
– Infection
– Metabolic: osteomalacia, hyperparathyroidism
– Paget disease
– Degenerative
– Neoplastic
• Traumatic: axial loading
• Scheuermann disease
• Osteoporosis ?!!

6. SN Location
• Intervertebral Location:
– almost 2/3 in the posterior part of the VEP,
– 1/3 in the middle part;
– anterior nodes rare
• However, traumatic Schmorl nodes occur
– Predominantly in the posterior VEP
– Mostly in sites that are particularly susceptible to
injury
• lower thoracic,
• thoracolumbar junction and
• upper lumbar spine

7. Pathologically Schmorl’s nodes
• Represent the nucleous
pulposus with degenerative
or inflammatory changes &
a sclerotic response in the
adjacent vertebral
spongiosa (trabeculat bone)
• The herniated NP may
become vasularised, and
lately ossified or calcified

8. Schmorl’s nodes Detection
• Conventional radiography depicts fewer SNs than cross-sectional
imaging methods
• Recently developed SNs may not be seen on
conventional radiographs due to the absence of
surrounding sclerosis
• Slab contact radiographs obtained with the use of
finegrain film allow detailed assessment of the presence
of SNs
• The size of SNs and the height of the intervertebral disk
space can be measured without any magnification.
Subtle bone changes accompanying those nodes also
can be depicted.

9. Forms of the VEP
VEP variations
A: A Schmorl node defined as
a focal indentation of the
VEP
B: The normal concave form of
the VEP
C: The cupid’s bow contour
has a smooth concavity in
the posterior portion of the
VEP
D: A straight VEP is present
when a line drawn from the
anterior edge to the
posterior edge of the
vertebral body is in contact
with the central portion of
the VEP
E: A fractured VEP
anterior posterior
The lower part of the vertebral body,
in a sagittal plane, is demonstrated

10. SN appear to be
VEP Reaction to Vertical Loading
• Normal concave VEP (negative association),
• A straight VEP seems to be more susceptible to
the formation of SN
• Explanations
– expansive pressure of the nucleus pulposus per
surface ratio, lower in a concave VEP (surface is
larger than straight VEP)
– there is more space for the nucleus pulposus,
therefore, there is less pressure because the volume
of an intervertebral space with concave VEPs is larger
than that associated with a straight VEP.

11. Frequency of Schmorl’s Nodes
Literature Discrepancy
• 58% in our elderly population
• 57% in the 2nd decade of life and 5% in the 6th decade of life
NO Discrepancy… WHY?
Schmorl Nodes of Elderly Persons
tend to be smaller and
have more surrounding sclerosis (healing)
less likely to have reactive concomitant bone marrow changes
that facilitate their detection with MR imaging (18).

12. • A common finding in the spines of the
elderly, with a frequency similar to that
reported for a younger population

13. Size and Volume of SN
• Mean anteroposterior
diameter
– 6 mm (range, 2–15 mm)
– 8.2 mm (range, 4–20
mm) by using MR
imaging
• Mean height of 3.3 mm
(range, 1–9 mm).
• No correlation between the
size and volume of the
Schmorl nodes and the
degree of disc degeneration
• Patients with LBP tended to
have larger Schmorl nodes
than those of asymptomatic
patients.

14. Clinical Controversy of SNs
• Most consider them to be asymptomatic ( frequent
finding in persons without back pain)
• However, in patients with back pain MR-based studies
showed
– a significantly higher frequency in the symptomatic group (19%)
in comparison with the control group (9%)
– more frequent frequency of enhanced signal intensity after IV
gadolinium
– more frequent frequency of those accompanied by bone marrow
changes
• An autopsy study showed
– 10% acute Schmorl nodes
– Acute or chronic trauma due to excessive axial loading may
cause Schmorl nodes that initially are symptomatic

15. SN and LBP
• On MRI: detected in 19% without back pain
• SN generally considered asymptomatic
• However, acute SN may be painful
• SN may give rise to disc degeneration
• The relationship of SN with disc disease and
their clinical significance as a source of low back
pain remain unknown
• Factors have been shown to have only modest
effects, have yet to be formally evaluated and
variability remains unexplained
– Environmental factors
• occupational physical loading,
• trauma, and
• smoking
– Genetic factors.

16. MRI SN-Characteristics
MRI SN-Characteristics
• Localized defect in a vertebral end plate
• With a well-defined herniation pit in the
vertebral body
• With or without a surrounding sclerotic
rim (low signal on all sequences)
• Small erosive defects of the end plate in
degenerate segments are not considered
SN
MR score
• Absent (score 0) or
• present (score 1) at cranial and caudal
vertebral levels T9 to L5.
• Multiple nodes at a particular vertebral
level were recorded as present (score 1)

17. Although MRI is considered the most
sensitive method for assessing the spine,
there is no accepted or standard definition
of SN, nor their size.

18. • a) Sagittal slab contact radiograph at the L3-4 level in a 74-year-old man
shows a
• Schmorl node (black arrow) in the distal VEP of L3 and shows a vacuum
phenomenon in the
• intervertebral disk (white arrow). (b) Gross specimen of the same slab
shows the Schmorl node,
• with displacement of the intervertebral disk (white arrow) in the VEP of L3.
Cleft formation (black
• arrow) in the intervertebral disk corresponds to the site of the vacuum
phenomenon.

19. Sagittal slab contact radiograph of
the L2-3 interspace in a 72-year-old
man shows
a Schmorl node (black arrow) in the
lower endplate
of L2 with traction osteophyte formation
(white arrow).
Sagittal slab contact radiograph of
the L2-3 interspace in a 59-year-old
man shows
a Schmorl node (black arrow) in the
lower endplate
of L2 and claw osteophyte formation
(white arrows).

20. Sagittal slab contact radiograph of
the T11 to L1 levels of the spine
in a 61-yearold
man shows Schmorl nodes
(straight arrows)
at the T11-12 level, with a straight
configuration
of the VEP and moderate disk
space
loss. A cupid’s bow contour
(curved arrows) is
at the T12-L1 level.

21. Anteroposterior and (b)
lateral specimen
radiographs
of the T11-L5 segment in a
60-year-old man show
the transition of
Schmorl nodes (white
arrows) in the VEPs of
T11 to L2 to a cupid’s
bow contour (black arrows)
of the VEP of L3 and L4.

22. Heritability of SN
• A number of genes have been implicated in disc degeneration
including
– an aggrecan gene polymorphism
– a vitamin D receptor and
– matrix metalloproteinase 3 gene alleles
• Several mechanisms may be proposed to account for genetic
factors influencing SN.
• Synthesis and breakdown of disc anatomic and biochemical
structures could be genetically determined and lead to accelerated
degenerative changes in some persons; for example,
• SN are more common in premature disc degeneration
– Scheuermann’s disease and
– the chondrodysplasias
• Disc disease may therefore be a constellation of several related
phenotypes, and SN may be at the more severe end of the
spectrum.

23. AGE and SN
• SN present during skeletal maturation are
unlikely to be the result of disc degeneration
• In subjects under 50 years of age
• disc degeneration in the T10–L1 region is more
frequent in discs with SN than in those without
SN;
• In subjects over 50 years of age this difference
becomes even more marked
• So, in the T10–L1 region, SN originating in
childhood or adolescence predispose to earlier-onset
disc degeneration.