This document provides a detailed overview of cervical spine anatomy and common cervical spine injuries seen on CT imaging. It begins with a description of cervical spine anatomy including the typical vertebrae from C3-C6 and the atypical C1 and C2 vertebrae. It then discusses common cervical spine injuries such as fractures of C1-C2, hangman's fractures of C2, and odontoid fractures. Classification systems for these injuries are provided along with example CT images. The document concludes with a brief discussion of subaxial cervical spine injuries.

1. CT Cervical Spine
Dr. Yash Kumar Achantani
OSR

2. Anatomy
The cervical spine is the upper part of the spine extending from
the skull base to the thorax.
It normally consists of seven vertebrae.
Its main function is to support the skull and maintain the relative
positions of the brain and spinal cord.
The normal cervical spine is curved - convex in front and concave
at the back (cervical lordosis)

3. Of the seven cervical vertebrae, C1 (atlas) and C2 (axis) have very
distinct anatomical features and are called atypical vertebra.
C3 through C6 have typical anatomy (typical vertebra), while C7
looks very similar.
Gross anatomy (typical vertebra)
• Small, oval-sized vertebral bodies
• Relatively wide vertebral arch with large vertebral foramen
• Relatively long, bifid (except for C7) inferiorly pointing spinous
processes
• Transverse foramina protecting the vertebral arteries and veins

4. Anterior components of the typical cervical vertebra :
•Body
•Pedicle
•Tranverse process
•Inferior articular process

5. Posterior components of the typical cervical vertebra :
•Lamina
•Bifid spinous process
•Superior articular process
•Inferior articular process

7. First cervical vertebra C1- Atlas.
 It is an atypical cervical vertebra with unique features.
 It articulates with the dens of the axis and the occiput
 The atlas is composed of an anterior arch and a posterior arch,
paired lateral masses, and paired transverse processes.
 It has the dens of the axis sit where a centrum (body) of a typical
vertebra would be.
 The transverse ligament holds the dens of the axis against the
anterior arch of the atlas and divides its vertebral canal into two
parts.
 The anterior 1/3 is occupied by the dens. The posterior 2/3
contains the spinal cord

9. Second cervical vertebra C2- Axis
It is an atypical cervical vertebra with unique features and important
relations that make it easily recognisable.
Its most prominent feature is the odontoid process, which is
embryologically the body of the atlas (C1) .
It plays an important role in rotation of the head with the majority of
movement occurring around the dens and at the atlanto-axial joint.

11. Indications for CT cervical spine
The most common indication for CT C-spine is suspicion of C-spine
trauma in case of MVA.
Other indications
 Persistent pain or radiculopathy, with > 6 weeks of conservative
therapy and inadequate response to treatment
 New or progressive neurologic symptoms or deficits, e.g. motor
or sensory loss attributable to cervical pathology.
 Fracture evaluation for suspected or known fracture

13. Injuries related to C1 vertebra
Craniocervical Dissociation.
i. Atlanto-occipital dissociation injuries
ii. Atlanto-axial subluxation
Occipital Condyle Injuries.
Fractures of the Atlas.
i. Type I: isolated posterior arch fracture
ii. Type II: isolated anterior arch fracture
iii. Type III (Jefferson fracture): anterior and posterior
arch fractures
iv. Type IV: comminuted lateral mass fracture

14. Atlanto-occipital dissociation injuries are severe and include both
atlanto-occipital dislocations and atlanto-occipital subluxations.
The key to the diagnosis, in addition to visualising gross disruption of
the normal alignment of the atlanto-occipital joint, hinges on using a
number of lines.
1. Basion-dens interval (BDI) >10 mm in adults
2. Basion-axial interval (BAI) >12 mm in adults
3. Powers ratio >1 (insensitive to a vertical distraction injury or
posterior dissociation)
4. Atlantodental interval (ADI)
>3 mm in adult males
>2.5 mm in adult females

16. Normal intervals of the
craniocervical junction.
Midsagittal half-space volume-
rendered CT image shows the
Atlantodental interval (solid line),
Basion-dens interval (double-
headed arrow),
Posterior axial line (dashed line),
Basion-to–posterior axial line
interval (dotted line),
C1–C2 spinolaminar distance
(parallel lines).

17. Volume-rendered CT image
shows the normal relationship of
an occipital condyle and the
lateral mass of C1, with close
apposition, and the nearly
equidistant intervals (solid lines)
along all points in the midsagittal
plane of the joint.

22. Volume-rendered CT image of a
patient with atlanto-occipital
dissociation after an MVC shows
The “V sign” of cranially divergent
predental lines (solid lines),
A widened basion-dens interval
(double-headed arrow),
The posterior axial line (dashed
line),
A widened basion-to–posterior axial
line interval (dotted line),
And a widened C1–C2 spinolaminar
interval (parallel lines).

23. (c) Coronal volume-rendered CT image of a 26-year-old man with craniocervical
distraction after a motorcycle collision shows bilateral widening of the atlanto-occipital
joints (AO) and the atlantoaxial joints (AA).
(d) Volume-rendered CT image of a 23-year-old man with craniocervical distraction after
a motorcycle collision shows the occipital condyles (OC) dissociated from the lateral
masses of the atlas and shifted anteriorly.

24. Midsagittal volume-rendered CT image
of a 23-year-old man shows a marked
widening (solid lines) of the atlanto-
occipital articulation, with anterior
translation of the condyles and skull
base.

25. Atlanto-axial subluxation is a disorder of C1-C2 causing impairment in
rotation of the neck. It may be associated with dislocation of the
lateral mass of C1 on C2.
There are several ways in which a subluxation can occur:
Anteroposterior subluxation
Vertical subluxation
Lateral subluxation
Rotatory subluxation

26. Rotatory subluxation, known as atlantoaxial rotatory fixation
(AARF) is characterised into four different types :
Type I: the atlas is rotated on the odontoid with no anterior
displacement
Type II: the atlas is rotated on one lateral articular process with 3 to 5
mm of anterior displacement
Type III: comprises a rotation of the atlas on both lateral articular
processes with anterior displacement greater than 5 mm
Type IV: characterised by rotation and posterior displacement of the
atlas

27. Fielding and
Hawkins
classification of
atlantoaxial
rotatory
subluxation

28. Volume-rendered CT
image of a 45-year-old
patient after an MVC
shows a widened
atlantodental interval
(solid line) secondary to a
transverse ligament injury.

29. McRae line is a radiographic line drawn on a lateral skull radiograph
or midsagittal section of CT or MRI, joining the basion and opisthion.
Normal position of the tip of dens is 5mm below this line. If the tip
of the dens migrates above this line it indicates the presence of
basilar invagination (atlanto-axial impaction).

31. Chamberlain line is a line joining the back of hard palate with
the opisthion on a lateral view of the craniocervical junction.
It helps to recognise basilar invagination which is said to be
present if the tip of the dens is >3 mm above this line.

33. The digastric (or biventer) line has been described and used to
evaluate basilar invagination on coronal recontructed CT image.
The digastric line is drawn between right and left digastric grooves.
The tip of the odontoid process and atlanto-occipital joint normally
project 11 mm and 12 mm below this line respectively. Basilar
invagination is present when atlanto-occipital joint projects at or
above this line.

36. The bimastoid line has been described and used to evaluate
basilar invagination on frontal skull plain film and coronal
reconstructed CT image.
The bimastoid line is drawn between the inferior tips of the of
mastoid processes bilaterally. The tip of the odontoid process of
C2 normally projects less than or equal to 10 mm above this line.
Basilar invagination is present when the tip of the odontoid
process projects above 10 mm.

39. Occipital Condyle Fractures
Anderson and Montesano introduced the most widely used
radiologic classification system for occipital condyle fractures,
describing three different patterns of injury:
Type I: comminution impaction injury resulting from axial
loading with minimal or no fracture displacement- Stable
Type II: skull base fracture extending through the occipital
condyle- Stable
Type III: alar ligament avulsion fracture- Unstable

40. Fractures may be unilateral with minimal distraction, may be
bilateral, or may extend in a ring like configuration along the anterior
foramen magnum, with bilaterality increasing the likelihood of
instability.
Approximately 75% of occipital condyle fractures are type III injuries.

41. Occipital condyle fractures in
three patients. (a) Coronal
multiplanar reformatted CT
image of a 24-year-old man
after a motorcycle collision
shows a right type I condylar
fracture (arrows) resulting
from impaction of the condyle
against the right lateral mass
of C1.

42. (b) Off-axial MIP image of a 52-year-old man after an MVC shows a type II
right occipital condyle fracture associated with a skull base fracture (arrows).
(c) Coronal MIP image of an 18-year-old man with severe polytrauma after an
MVC shows an avulsion fragment off the right occipital condyle (type III
occipital condyle fracture).

43. Fractures of the Atlas
Atlas fractures account for 25% of craniocervical injuries. As many as
44% of atlas fractures have associated fractures of the axis.
Type I: Isolated posterior arches ----Stable
Type II: Isolated anterior arch ----Stable

44. Type III: Bilateral posterior arch with bilateral or unilateral anterior
arch (“Jefferson burst”)---- Stability Depends on integrity of
transverse ligament.
Type IV: Lateral mass ----Stable
Type V: Transversely oriented anterior arch fractures (avulsion of
longus colli or atlantoaxial ligament)

45. Fractures of the atlas in three patients. (a) Off-axial MIP image of a 27-year-old woman
after an MVC shows bilateral posterior arch fractures (TYPE 1) . Head rotation within the
physiologic range results in asymmetry of the lateral atlantodental intervals.

46. (b) Off-axial MIP image of a 49-year-old woman after an MVC shows a three-part
Jefferson fracture of the atlas (TYPE 3) . A congenital cleft (arrow) is incidentally
depicted anteriorly at the foramen transversarium. The cleft is distinguished from a
fracture by its smooth sclerotic appearance and because ring fractures should occur in
at least two parts.

47. (c) Off-axial MIP image of a 50-year-old
female pedestrian who was struck by a
motor vehicle shows unilateral fractures of
the left anterior and posterior arches, with
separation of the lateral mass (TYPE 4).

48. Injuries related to C2 vertebra
Hangman fracture
Odontoid fracture

49. Hangman fracture, also known as traumatic spondylolisthesis of the
axis, is a fracture which involves the pars interarticularis of C2 on
both sides, and is a result of hyperextension and distraction.
Levine and Edwards classification is used to classify hangman
fractures of C2.
Type I: fracture with <3 mm antero-posterior deviation
no angular deviation
Type II: fracture with >3 mm antero-posterior deviation
significant angular deviation
disruption of posterior longitudinal ligament
Type IIa: the fracture line is horizontal/oblique (instead of vertical)
significant angular deviation without anterior translation
Type III: type I with bilateral facet joint dislocation

50. Hangman fracture (a) Off-axial MIP image of an 18-year-old patient after a fall from
an all-terrain vehicle shows a type I hangman fracture with bilateral fractures of the
pars interarticularis.
(b) Sagittal half-space slab volume-rendered CT image of an 18-year-old patient
(same patient as in a) shows no translation or angulation of C2.

51. Hangman fracture
(c) Sagittal volume-rendered CT image of a 27-year-old woman with a type II
hangman fracture after an MVC shows anterior translation and angulation of C2. The
patient also had bilateral posterior arch fractures from hyperextension.
(d) Off-axial MIP image of a 62-year-old woman with an atypical type II hangman
fracture after an MVC shows a pars fracture on the right and an oblique fracture
through the posterolateral vertebral body.

52. (f) Sagittal volume-rendered CT image
of a 26-year-old woman with a type IIa
hangman fracture after an MVC shows
a pars interarticularis fracture with
anterior angulation of the body of C2
but no anterior translation.

53. Sagittal volume-rendered CT
image of a 30-year-old
woman with a type III
hangman fracture after an
MVC shows marked anterior
translation of C2 with facet
fracture-dislocation.

54. Nonodontoid nonhangman fracture.
Coronal MIP image of a 73-year-old
man after an MVC shows a
nonodontoid nonhangman fracture
involving the right lateral mass of C2.

55. Odontoid process fracture
Also known as the peg or dens fracture, occurs where there is a
fracture through the odontoid process of C2.
The Anderson and D'Alonzo classification is the most commonly
used classification of fractures of the odontoid process of C2.
Type I
Rare
Fracture of the upper part of the odontoid peg
Above the level of the transverse band of the cruciform ligament
Usually considered stable

56. Type II
Most common
Fracture at the base of the odontoid
Below the level of the transverse band of the cruciform ligament
Unstable
High risk of non-union
Type III
Through the odontoid and into the lateral masses of C2
Relatively stable if not excessively displaced
Best prognosis for healing because of the larger surface area of the
fracture

58. (a)Coronal multiplanar reformatted CT image of a 51-year-old man after a
motorcycle collision shows an oblique fracture of the odontoid tip (type
I odontoid fracture).
(b) Coronal volume-rendered CT image of a 24-year-old patient after a
rollover MVC shows a type II odontoid fracture.

59. (c) Sagittal MIP image of an 86-year-old patient after a fall from standing
shows a type IIa odontoid fracture with posterior displacement, posterior
angulation, and comminution.
(d) Coronal multiplanar reformatted CT image of a 78-year-old patient
involved in an MVC shows a type III dens fracture (arrows).

60. Variants
Os odontoideum
Persistent ossiculum terminale

61. Os odontoideum is an anatomic variant of the odontoid
process of C2 and needs to be differentiated from persistent
ossiculum terminale and from a type 2 odontoid fracture.
It can be associated with atlantoaxial instability.
Although it was originally thought to be a congenital lesion due to a
failure of the centre of ossification of the dens to fuse with the body
of C2, it may actually represent an unremembered and/or
unrecognised fracture through the dens growth plate before the age
of 5 or 6.
There may be associated instability and chronic symptoms.

64. Ossiculum terminale appears as a secondary ossification
centre of the dens between 3-6 years and normally fuses by 12
years.
Failure of fusion results in a persistent ossiculum terminale and is
considered a normal anatomical variant of the axis.
It lies above the transverse alar ligament and is therefore
considered to be stable and it very rarely causes symptoms.

66. Coronal bone window CT image
shows
Ossiculum terminale

67. Injuries of the Subaxial Cervical Spine
Subaxial injuries account for 65% of cervical spine fractures and
75% of dislocations .
Two scoring systems have been developed that specifically
incorporate multidetector CT for sub axial injuries:
1.The cervical spine Subaxial Injury Classification and Scoring
(SLIC) system.
2.The cervical spine injury severity score.
(SLIC system is more acceptable and easy)

68. The SLIC system, which was introduced in 2007 by Vaccaro et al
The SLIC system is made up of three separately graded
components, each representing major independent predictors of
outcome.
The three components of SLIC are
(a) Morphologic findings of bone spinal column disruption,
(b) The integrity of the discoligamentous complex, and
(c) Neurologic status.
The three scores for these three components are summed to give
the SLIC score (total score). Combined scores of 5 or more
indicate the need for surgical intervention. Injuries with scores of
3 or less can be managed without surgery, and scores of 4 are
indeterminate

69. SLIC Morphology Score
The SLIC morphology score describes the structural integrity and
relationships of vertebrae at an injured motion segment, with higher
scores corresponding with worse outcomes and an increased need
for surgery.
Morphology can be characterized with CT alone, and complete
discoligamentous injury can also usually be diagnosed with a high
degree of specificity in more-severe cases.

71. Compression (Score of 1) and Burst (Score of 2).—
Compression and burst fractures are characterized by loss of
vertebral body height without evidence of distraction or translation,
regardless of whether focal kyphosis is present.

72. Compression burst fracture.
Sagittal half-space slab
volume-rendered CT image of
a 23-year-old man after an
MVC shows a burst fracture of
C7 without associated facet
distraction.

73. Distraction (Score of 3)
Distractive injuries of the subaxial cervical spine are characterized by
dissociation in the vertical axis. Distraction may occur anteriorly as a
result of hyperextension or posteriorly from hyperflexion.
Hyperflexion injuries range from facet subluxation, with decreased
apposition or diastasis of the articular surfaces.
Facets are considered subluxated when there is less than 50%
overlap of the articular surfaces or more than 2 mm of diastasis.

74. Associated findings include
(a)posterior disk space widening with angulation greater than 11° and
(b) focal kyphotic deformity.

75. Flexion-distraction injuries in two patients. (a) Oblique volume-rendered CT
image of a 39-year-old woman after an MVC shows bilateral C5-C6 facet
distraction (arrows).
(b) Sagittal volume-rendered CT image of a 39-year-old woman (same
patient as in a) shows C5-C6 kyphotic angulation and posterior disk space
widening.

76. (c) Sagittal volume-rendered CT image of a 43-year-old woman who fell a
short distance and landed on her head shows perched facets (arrow) at C5-
C6, with focal kyphotic deformity.
(d) Oblique volume-rendered CT image of a 43-year-old woman (same patient
as in c) shows interspinous widening (*) associated with the C5-C6 facet
perch (arrow).

77. Hyperextension—Extension-type distraction injury is synonymous
with the term hyperextension dislocation and results from
disruption of the anterior longitudinal ligament and intervertebral
disk.
These injuries manifest with “extension teardrop” fracture, an
avulsed fragment of the anterior inferior corner of the involved
vertebral body, in 65% of cases, most commonly at C2.
Extension teardrop fracture is characteristically a thin fracture
fragment greater in the horizontal than the vertical dimension, is
often associated with anterior disk space widening.
Other stigmata of hyperextension injury such as facial trauma and
compression fractures of the facets, laminae, and spinous processes
may be seen

78. Extension-distraction injury.
Sagittal multiplanar
reformatted CT image of a 61-
year-old patient after a fall
from standing shows a
“hyperextension teardrop”
fracture (arrow) off the anterior
inferior lip of C2, with
associated posterior spinous
process fractures of C6-T1.

79. Translation or Rotation (Score of 4)—
Translation or rotation is demonstrated by vertebral offset in the
horizontal axis and may occur with or without fracture.
A pure translation of one vertebra relative to another may occur
when discoligamentous structures are disrupted bilaterally, or
rotation may occur when an intact facet serves as a pivot point.
Translation or rotation injuries can result from unilateral or
bilateral facet dislocations or fracture-dislocations.
A horizontal distance of 3.5 mm between the posterior aspects of
the rostral and caudal vertebral body at any given motion segment
is used as a cutoff for translational injury .

80. Unilateral locked facets usually cause less than 50% anterior
translation of the rostral vertebral body, whereas bilateral facet
dislocations result in 50% or more translation.

81. Translation injuries. (a) Coronal
posterior volume-rendered CT
image of an 85-year-old patient
after an MVC shows bilateral
locked facets (arrows) at C5-
C6.

82. (b) Sagittal volume-rendered CT
image of a 24-year-old patient who
was an unrestrained backseat
passenger in an MVC shows locked
facets at C5 (white arrow) on C6 (black
arrow), with greater than 50%
translation of the C5 vertebral body.

83. Translation injuries: Rotation-translation injury in a 61-year-old patient who was an
unrestrained driver in an MVC. (a) Axial MIP image shows left C6 pedicle and laminar
fractures (arrows), with separation of the lateral mass (*). (b) Multiplanar reformatted CT
image through the midsagittal plane of the spine below the injured segment shows off-
center spinous processes of C2 through C6 (arrow). (c) Sagittal half-space slab volume-
rendered CT image shows less than 50% anterior translation of the C6 vertebral body,
with rotated vertebral bodies at and above the injured level (arrow).

84. Translation injuries: flexion teardrop
injury in a 27-year-old woman who
was a victim of assault. (a) Sagittal
half-space slab volume-rendered CT
image shows the flexion teardrop
injury pattern, with the classic findings
of a triangular fragment (arrow) off the
anterior inferior C6 vertebral body and
posterior translation of the vertebral
body and posterior elements, resulting
in facet widening (*).

85. (b) Axial MIP image shows a sagittal
fracture line (arrow) through the C6
vertebral body posterior to the teardrop
fragment.

86. SLIC Discoligamentous Complex Score
The term discoligamentous complex refers to
(a) The anterior longitudinal ligament, intervertebral disk, and
posterior longitudinal ligament anteriorly and
(b) The ligamentum flavum, facet capsules, interspinous ligament,
and supraspinous ligament posteriorly.
Abnormal bone relationships at CT are the primary way that
discoligamentous complex injuries are diagnosed initially.

88. SLIC Neurology Score

90. Clay-shoveler fracture
Clay-shoveler fractures are fractures of the spinous process of a
lower cervical vertebra.
Often these injuries are unrecognised at the time and only found
incidentally years later when the cervical spine is imaged for other
reasons.
Acutely they tend to be associated with :
Motor vehicle accidents
Sudden muscle contraction
Direct blows to the spine

91. Sagittal CT image of a patient
with neck pain after lifting a
heavy object.
Shows fracture of spinous
process of C7 vertebra.

94. Vertebral Anomalies

95. Hemivertebra
Hemivertebra is a type of vertebral anomaly and results from a lack of
formation of one half of a vertebral body. It is a common cause of congenital
scoliosis.
It falls under the spectrum of segmentation anomalies and can involve one or
multiple levels.
A hemivertebra acts as a wedge within the vertebral column, resulting in
curvature away from the side on which it is present.

96. Types of hemivertebra
On the basis of attachment
•Fully segmental (free)
• not attached to either vertebra above or below
• most concerning
•Semi segmental: half segment is fused with vertebra above or below with no
intervening intervertebral disc
•Non segemental
• not separated from (i.e. connected to) either level above or below
• causes less of a concern
•Incarcerated
• joined by pedicles to levels above and below
• causes less of a concern

97. On the basis of orientation
1. Dorsal hemivertebra: classically results in kyphosis
2. Lateral hemivertebra: classically results in scoliosis
3. Ventral hemivertebra (extremely rare): results in lordosis

98. This case shows a semi-segmental
left thoracic hemivertebra.

99. Block vertebra
Block vertebra is a type of vertebral anomaly where there is a failure
of separation of two or more adjacent vertebral bodies.
1. Combined vertebrae may be of normal height, short, or tall
2. Disc space is frequently rudimentary or absent
3. The "wasp-waist sign" is seen in congenital block vertebra

100. CT scan revealed block vertebra on C5 and
C6 vertebral level (arrowheads)

101. Butterfly vertebra
Butterfly vertebra is a type of vertebral anomaly that results from the
failure of fusion of the lateral halves of the vertebral body because of
persistent notochordal tissue between them.
There is widening of the affected vertebral body. The bodies above
and below the butterfly vertebra adapt to the altered intervertebral
discs on either side by showing concavities along the adjacent
endplates.
Some bone bridging may occur across the defect which usually
happens in the thoracic or lumbar segments of the spine.

103. Arcuate foramen
The arcuate foramen (foramen arcuale atlantis, ponticulus posticus or
posterior ponticle, or Kimerle anomaly) is a frequently encountered
normal variant of the atlas.
It develops by calcification of the posterior atlanto-occipital
membrane. The atlantic portion (V3) of the vertebral arteries pass
through this foramen.
Incidence is ~8% (range 1-15%) and it is more common in females. It
has a variable morphology, can be complete or incomplete and may
be unilateral or bilateral.

104. The arcuate foramen is contained within the circle annotation.

105. Other Conditions involving Cervical Spine

106. Ossification of the posterior longitudinal ligament
Ossification of the posterior longitudinal ligament (OPLL) is typically an entity
seen in patients of Asian descent, although it is seen in all ethnic groups.
Location
cervical: 75%
thoracic: 15%
lumbar: 10%
Types of OPLL
type 1 : continuous (ossification of several vertebral segments)
type 2 : segmental (several segments are affected, ossification is disrupted)
type 3 : mixed (mix of 1 and 2)
type 4 : localised (circumscribed, only one or two segments)

107. Sagittal bone window CT showing OPLL

108. Diffuse idiopathic skeletal hyperostosis
Diffuse idiopathic skeletal hyperostosis (DISH), also referred to as Forestier
disease, is a common condition characterised by bony proliferation at sites of
tendinous and ligamentous insertion of the spine affecting elderly individuals.
On imaging, it is typically characterised by the flowing ossification of the anterior
longitudinal ligament , The cervical and thoracic spines, in particular, are
affected.
DISH most commonly affects the elderly, especially 6th to 7th decades.
Imaging:- Florid, flowing ossification is noted along the anterior or anterolateral
aspects of at least four contiguous vertebrae, so-called flowing ossifications
Disc spaces are usually well preserved
Ankylosis is more commonly seen in the thoracic than in the cervical or lumbar
spine.

109. There is calcification of anterior longitudinal ligament resulting in an irregular melting candle
wax like calcified mass anterior to the C3 to T4 vertebrae, with normal appearing intervertebral
disc spaces.

110. Rheumatoid arthritis
Rheumatoid arthritis (RA) is a chronic autoimmune multisystemic
inflammatory disease which affects many organs but predominantly attacks
the synovial tissues and joints.
The cervical spine is frequently involved in RA ( in approximately 50% of
patients), whereas a thoracic and lumbar involvement are rare. Findings
include:
1. Erosion of the dens
2. Atlantoaxial subluxation
3. Atlantoaxial impaction (cranial settling): cephalad migration of C2
4. Erosion and fusion of uncovertebral (apophyseal joints ) and facet joints
5. Osteoporosis and osteoporotic fractures
6. Erosion of spinous processes

111. Sagittal bone window CT image shows Severe degenerative change at the atlanto-dens
articulation with erosions.

112. Limitations of Multidetector CT
Although multidetector CT is often sufficient for making the binary
determination of whether surgery is necessary or not, important
determinants of management, including disk herniations,
ligamentum flavum infolding, cord swelling, contusion or
hemorrhage, and epidural hematoma, are not well evaluated with
CT but are clearly depicted at MR imaging.