II. Goal
Part 1 presented diagnostic definitions and clinical classifications. Part II provides
corresponding image examples as “comparison images”.
The goal of the reference material provided in part 2 is to support image evaluation
as part of the medical expert opinion for occupational disease nos. 2108 and 2110
with comparative image analysis and to illustrate the image criteria and classifications
of findings specified in the consensus paper in a reproducible manner.
Clinical and procedural information for the interdisciplinary expert opinion process
(symptoms, images) is provided in part I and its use is recommended for quality assurance.
III. “Comparison images”
The diagnostic criteria listed in the consensus paper [4 ] are to be analyzed in the expert opinion for occupation disease nos. 2108 and 2110
both for the cervical spine and the lumbar spine. The report should include osseous
(projection radiography) and intervertebral disc findings (MRI).
Using comparison images ([Fig. 1 ], [2 ], [3 ], [4 ], [5 ], [6 ], [7 ], [8 ], [9 ]), the following list of “diagnostic criteria” based on definitions and image analysis
[4 ] allows:
Fig. 1 a Normal cervical spine finding, normal distances between the vertebrae of the cervical
spine are as follows: C2/3 < C3/4 < C4/5 < C5/6 ≥ C6/7. b Normal lumbar spine finding, normal distances between the vertebrae of the lumbar
spine are as follows: L1/2 < L2/3 < L3/4 < L4/5 ≥ L5 / S1.
Fig. 2 a Chondrosis grade I – cervical spine: Height reduced at the midline level to half
height, 40 % in this example. b Chondrosis grade I – lumbar spine: Height reduced at the midline level ≥ 1/5 to 1/3.
c Chondrosis grade II – cervical spine: Height reduced at the midline level > ½, 55 %
in this example. d Chondrosis grade II – lumbar spine: Height reduced at the midline level > 1/3–1/2,
45 % in this example. e Chondrosis grade III – lumbar spine: Height reduced at the midline level > ½, 65 %
in this example. In this example, the intervertebral disc space L1/2 can only be compared
with segments L2/3 and 3/4. f Chondrosis grade IV – lumbar spine, ankylosing chondrosis. Caution: To be differentiated
from traumatic and dysontogenetic block vertebrae!
Fig. 3 The figure shows the typical binary image criterion of sclerosis and its stages based
on the definition in the “consensus paper”. Note: In < 45-year-olds, grade I sclerosis
is considered not age-typical according to the consensus paper. However, since degenerative
findings in the cervical spine are classified as unlikely occupational disease nos.
2108 and 2110, this differentiation is not necessary for practical use in the assessment
of occupational disease nos. 2108 and 2110. Intraindividual calibration is important
in the case of a visible increase in sclerosis, thus the comparison with the other
visualized vertebral bodies. a Sclerosis grade I – cervical spine. Visible increase in sclerosis of the end plates
of C5 and C6 in the case of chondrosis and spondylosis in the segment. Caution – intraindividual
calibration! b Sclerosis grade II – cervical spine. Sclerosis of the end plates > 1 mm wide. c Sclerosis grade I – lumbar spine. Visible increase in sclerosis of the end plate
of L3 with reduced height due to intervertebral disc damage in the segment. Caution
– intraindividual calibration! d Sclerosis grade II – lumbar spine. Sclerosis > 2 mm wide.
Fig. 4 The figure shows the typical binary image criterion of spondylosis and its stages
based on the definition in the “consensus paper”. The switch from age-typical to not
age-typical findings is shown as follows: cursive = not age-typical for < 50-year-olds;
bold = not age-typical in people over the age of 50. In addition, the location makes
occupational disease nos. 2108 and 2110 likely (e. g., lower lumbar spine – see consensus
paper) or rather unlikely (e. g., cervical spine findings – see consensus paper).
a Spondylosis of the cervical spine grades 1–3. Cervical spine: Grade I: 1 mm, grade
II: 2–3 mm, grade III: > 3 mm. b Spondylosis of the cervical spine grade 4. Signs of bridging or complete bridging.
c Retrospondylosis of the cervical spine grades 1–2.
Fig. 5 a Spondyloarthritis – lumbar spine grade I: Increased sclerosis of the vertebral joints
visible. Lumbar spine grade II: Additional enlargement or outgrowths at the facet
joints. b Spondyloarthritis – cervical spine grade I: Increased sclerosis of the vertebral
joints visible. Cervical spine grade II: Additional enlargement or outgrowths at the
facet joints. c Uncovertebral arthrosis/neoarthrosis at the uncinate process.
Fig. 6 a Intervertebral disc degeneration in the lumbar spine classified as Pfirrmann I–IV.
b Intervertebral disc degeneration in the lumbar spine classified as Pfirrmann V.
Fig. 7 a Intervertebral disc protrusion L4/5. b Intervertebral disc protrusion L4/5. c Prolapse: Intervertebral disc displacement with cranial or caudal exceeding of the
marginal contours of the vertebral body end plates on sagittal images, terminating
transversely at an acute angle to the contour of the intervertebral disc. d Prolapse: Intervertebral disc displacement with cranial or caudal exceeding of the
marginal contours of the vertebral body end plates on sagittal images, terminating
transversely at an acute angle to the contour of the intervertebral disc.
Fig. 8 Synopsis of changes in the lumbar spine, sag.
Fig. 9 Synopsis of changes in the cervical spine, a. p.
Confirmation/exclusion (“binary image criteria”: see part I),
Semiquantitative determination (grading) of the degree of severity,
Synoptic assessment of a “load-conforming damage pattern”, and thus
Morphological differentiation from non-occupational diseases (e. g., “competing factors”/“E-constellations”:
[4 ]).
Under consideration of all individual findings, their classification as age-typical/not
age-typical, and work-related analyses, a constellation of findings (groups A, B,
C, etc.) can be developed.
User information regarding comparison images:
Use of the “comparison images” is preceded by the definition of the diagnostic criteria
(according to Dihlmann for radiography and Pfirrman or Vahlensieck for MRI) and grading
according to the consensus paper [4 ].
[Fig. 1a, b ] show “unremarkable findings” (i. e., normal configuration and structure as the reference
image for systematic image analysis). Comparison images for chondrosis are shown in
[Fig. 2a–f ], sclerosis in [Fig. 3a–d ], spondylosis in [Fig. 4a–c ], spondyloarthritis in [Fig. 5a–b ], intervertebral disc degeneration in [Fig. 6a, b ], and intervertebral disc extrusion in [Fig. 7a, b ].
The arrows identify the pathological findings in each image.
A. “Normal findings”
Normal structure and contour of the spine; physiological, cranio-caudal increase and
decrease in the height of the intervertebral spaces.
B. “Degenerative diagnostic criteria”
Chondrosis (syn. chondrosis intervertebralis), see 5.7 Consensus recommendations)
Definition: Disc damage with a decrease in the intervertebral spaces on lateral images
without changes in the bony end plates. [Table 1 ] shows the grading, and [Fig. 2a–f ] show image examples.
Tab. 1
Grades of chondrosis.
Grade
Reduced height, measured in the middle
Grade I
Lumbar spine >/ = 1/5–1/3
Cervical spine to 1/2
Grade II
Lumbar spine > 1/3–1/2
Cervical spine > 1/2
Grade III
Lumbar spine > 1/2
Grade IV
Lumbar spine, ankylosing chondrosis
Processing information:
The grade of chondrosis is determined primarily by comparison with the comparison
images. An exact measurement of the intervertebral disc height [5 ]
[6 ]
[7 ] can support the conclusion in cases of doubt. Even in the case of a clear finding
(grade III chondrosis), a measurement can be helpful with respect to a comparative
decrease in the height of additional intervertebral discs.
In the case of clear constellations of findings that meet the requirement for recognition
(three affected intervertebral discs with chondrosis > grade II and/or slipped disc
and/or secondary spondylosis), this measurement can be omitted. Measurement is also
not necessary if there is clearly no decrease in the height of an intervertebral disc.
The measurement of the intervertebral disc heights of the lumbar spine as described
by Hurxthal [6 ]
[7 ] cannot be used in the case of narrowing of the intervertebral discs in all segments
due to false-negative results. A comparative description under consideration of “normal
findings” is usually sufficient in such cases ([Fig. 1a, b ]).
Measurement of the intervertebral disc heights of the cervical spine is not established
since current data does not allow comparable classification as in the lumbar spine.
Incorrect measurement results can also occur when the segments are not measured using
an orthogonal line so that the measurement points do not take the exact mid-line of
the oval surfaces of the end plates into account (“midline measurement”).
A “load-conforming damage pattern” is defined as intervertebral disc damage with at
least grade II chondrosis and/or a slipped disc, and with secondary spondylosis or
a multisegmental damage pattern, with more than 2 segments being affected. MRI is
usually necessary to show this.
[Fig. 2a–f ] show the grades of sclerosis.
Sclerosis
Definition: Significant sclerosis of the end plates that is independent of a reduction
of the height of the intervertebral disc. [Fig. 3 ] shows the grades, and [Fig. 3a–e ] show image examples.
Sclerosis is an osseous reaction to an “increase in pressure due to edema” and the
subsequent “loss of the buffer function” of the intervertebral disc [8 ]: i. e., no sclerosis without chondrosis in occupational diseases (not the case in
traumatology!).
“Intraindividual comparison” is important because it is used for “personalization”
and for the differential diagnosis of constitutional variants.
Chondrosis or a slipped disc can also be recognized without sclerosis. Sclerosis indicates
a longer disease course, which must be taken into consideration in the assessment
of the cause: For example, in the case of grade II chondrosis or a slipped disc but
the load-bearing job ended more than 5 years ago, the causal relationship is questionable
in the absence of sclerosis.
[Fig. 3a–e ] show the grades of sclerosis.
Spondylosis (syn. spondylosis deformans), see page 8 “consensus recommendations”
Definition: Bony overgrowths at the margins below and/or above the end plates and/or
on the ventral and anterior side surfaces of the vertebral bodies. [Fig. 4 ] shows the grades, and [Fig. 4a–c ] show image examples.
Secondary spondylosis is a particularly positive indication of occupational disease
when it occurs in segments not affected by chondrosis or prolapse. As a rule, secondary
spondylosis must occur in at least 2 segments, but the segments do not have to be
adjacent.
The formation of spondylotic osteophytes of the thoracic spine are generally not taken
into consideration.
The main pathological transformation process in an occupational disease occurs in
the intervertebral disc, manifests as osseous damage in the form of a “submarginal
osteophyte”, and is an expression of significant disc damage according to Dihlmann
[8 ]. This must be taken into consideration in image analysis in order to correctly determine
the causality giving rise to liability. Secondary spondylosis is significant because
this is the most important finding from an epidemiological standpoint in the population
of heavy workers [9 ].
Degenerative spondylosis must be differentiated from diffuse idiopathic skeletal hyperostosis
(Forestierʼs disease). The excessive bone formation in diffuse idiopathic skeletal
hyperostosis is an independent disease pattern. The ossifications in diffuse idiopathic
skeletal hyperostosis do not affect the intervertebral disc spaces. Reduced height
of the intervertebral discs is typically not seen.
It is also necessary to differentiate syndesmophytes, e. g., in ankylosing spondylitis,
growing in the longitudinal direction of the spinal column from vertebral body to
vertebral body. Parasyndesmophytes [8 ] are seen, for example, in Reiterʼs disease or psoriatic arthritis. They also grow
in the longitudinal direction but are only in contact with one vertebral body or grow
exclusively in the perivertebral connective tissue – i. e., not submarginal-linear.
[Fig. 4a, b ] show the definition and stages of spondylosis, while [Fig. 4c ] shows retrospondylosis.
Retrospondylophytes (see page 9 “consensus recommendations”)
Definition: Posterior spondylophytes. The stage is determined based on tangential
measurement: stage I = up to 2 mm and stage 2 = 3 mm or larger. [Fig. 5 ] shows an example.
Spondyloarthritis
Definition: Degenerative changes in the vertebral joints of one or more segments of
motion
The reduced height of the intervertebral disc results in a decrease in the shock-absorbing
function of the disc. Spondyloarthritis can only be considered related to intervertebral
disc/occupational disease when it is caused directly by a decrease in the height of
the intervertebral discs. It can also occur as an independent disease pattern in polyarthritis
or as a result of an asymmetrical load in transitional vertebra or scoliosis (chondrosis
not required).
The grade is determined based on the extent of the sclerosis – grade I: Increased
sclerosis of the vertebral joints visible. Grade II: Additional enlargement or outgrowths
at the facet joints.
Image examples ([Fig. 5a–c ]):
Uncovertebral arthrosis of the cervical spine
Definition: A specific arthrosis-like process of the cervical spine, neoarthrosis
of the uncinate process [Fig. 5c ] shows an example:
Degeneration of intervertebral discs
Descriptions:
A loss of signal in intervertebral discs correlates with histologically verifiable
degenerative changes.
Signal loss and a lack of differentiation of the nucleus and annulus are the direct
criteria for recognition required in the consensus paper.
All findings > Pfirrmann III are pathological – further differentiation is not required.
This is currently only possible with MRI ([Table 2 ]).
Tab. 2
Classification of intervertebral disc degeneration according to Pfirrmann.
Grade
Intervertebral disc structure
Differentiation of annulus/nucleus
T2 signal (MRI)
Intervertebral disc – height
I
Homogeneously white
Yes
Hyperintense
Normal
II
Inhomogeneous, possible horizontal bands
Yes
Hyperintense
Normal
III
Inhomogeneously gray
Unclear
Intermediate
Normal to slightly reduced
IV
Inhomogeneously dark gray
No
Intermediate to hypointense
Normal to moderately reduced
V
Inhomogeneously black
No
Hypointense
Collapsed
Determination of the degree of degeneration according to Pfirrmann [10 ] is an additional criterion in the B-constellation of the consensus paper (see below).
In light of the difficult to reproduce and thus usually unnecessary measurements for
chondrosis, this “additional criterion” plays a decisive role in the recognition of
occupational disease, particularly in the case of mild or moderate chondrosis.
Higher grades on MRI are used to supplement the finding or for differentiating between
competing factors.
The term “black disc” is used a collective term in the literature for multiple Pfirrmann
stages and should no longer be used. In addition, differentiation of higher stages
is not necessary in the recognition process (Pfirrmann grade III is sufficient evidence
of damage).
[Fig. 6a, b ] show the grades of intervertebral disc degeneration according to Pfirrmann.
Intervertebral disc extrusion
Definitions
Protrusion:
Intervertebral disc displacement without cranial or caudal exceeding of the marginal
contours of the vertebral body end plates on sagittal images, terminating transversely
at an obtuse angle to the contour of the intervertebral disc ([Fig. 7a, b ]).
Prolapse:
Intervertebral disc displacement with
cranial or caudal exceeding of the marginal contours of the vertebral body end plate
on sagittal images
and/or terminating transversely at an acute angle to the contour of the intervertebral
disc ([Fig. 7c, d ])
and/or with ventral dural sac compression of at least 50 %
and/or with projection of the intervertebral disc >/ = 5 mm over the posterior edge
of the vertebral body.
Protrusion of more than 5 mm over the connecting line of the posterior boundary of
the rear edge of the vertebral body is considered equivalent to prolapse in the assessment.
Summary of causality test procedure via imaging
Step 1: Determination of the height of the intervertebral disc segment (L4 / L5 and/or L5 / S1
or higher)
Step 2: Determination of the constellation according to the consensus paper [4 ] (positive workplace analysis required) L4 / L5 and/or L5 / S1 = B-constellation,
above L4 / L5 = C-constellation
Step 3: Degree of intervertebral disc damage in the most affected segment (not typical for
age vs. typical for age)
[Fig. 8 ], [9 ] summarize the previously described findings.
