imagingofspinaltrauMA

1. Introduction, clinical considerations and imaging
techniques overview
2. Plain Film Radiography and CT of the Cervical Spine:
Normal Anatomy
3. Plain Film Radiography and CT of the Cervical Spine:
Classification and Subtypes of Spinal Injury
4. Imaging of Thoracolumbar Spinal Injury
5. Magnetic Resonance Imaging of Acute Spinal Trauma
6. Imaging of Pediatric Spinal Injury

 During ancient times, spinal trauma and paralysis was
untreatable and fatal
 Spinal cord injury (SCI) still remains a significant cause of
disability
 The majority (81%) are males and the average age is
relatively young at 32.8 years.
 Approximately half the spinal cord injuries occur from
motor vehicle crashes. Falls from >10 feet, gunshot
wounds, motorcycle crashes, crush injuries, and
medical/surgical complications account for most of the
remaining cases

 In addition to the obvious quality-of-life implications
of such injuries, life expectancy is also affected, being
approximately half of that of otherwise matched
individuals

 Radiography
 Computed Tomography (CT)
 MRI

 Only one third of spinal trauma patients present
initially with a neurological deficit
 Moreover, important clinical features such as pain from
injury may be masked by other
injuries, medication, and drug and alcohol intoxication
 Defining the group of subjects who are at risk for
cervical spine fracture and therefore in whom imaging
is appropriate remains challenging.

The NEXUS study indicates that cervical spine imaging is not necessary in trauma patients
who meet all of the following five criteria:
1. No midline cervical spine tenderness
2. No focal neurological deficit
3. Normal level of alertness
4. No intoxication
5. No painful distracting injury
 NEXUS - National Emergency X-Ray Utilization Study, United States, published
in 2000
 Source: Hoffman J, Mower W, Wolfson A, et al. Validity of a set of clinical criteria to rule
out injury to the cervical spine in patients with blunt trauma. N Eng J Med. 2000;343:94–
99.
sensitivity - 99.6%
specificity - 12.6%

 Imaging of the cervical spine is not necessary if patients are alert (GCS 15) and all of the
conditions detailed below are met.
1. No high-risk factor present, including:
Age 65 or more years
Dangerous mechanism, including:
Fall from >3 meters/5 stairs
Axial load to head (diving)
High-speed vehicular crash (60 mph, rollover )
Bicycle crash
Motorized recreational vehicle crash
Paresthesias in extremities
3. Able to actively rotate neck (45 degrees left and right)
 Source: Stiell I, Wells G, Vandemheen K, et al. The Canadian C-spine rule for radiography
in alert and stable trauma patients. JAMA. 2001;286: 1841–1848.
2. Any low-risk factor is present, including:
Simple rear-end vehicular crash mechanism,
excluding:
Pushed into oncoming traffic
Hit by bus/large truck
Rollover
Hit by high-speed vehicle
Sitting position in emergency department
Ambulatory at any time
Delayed onset of neck pain
Absence of midline cervical tenderness
99.4% - sensitivity
45.1% - specificity

 The three-view radiography series
 antero-posterior,
 lateral, and
 open mouth odontoid
is still the imaging modality of choice as initial study for
symptomatic patients
( as recommended by the American College of Radiology Appropriateness Criteria
and the Advanced Trauma Life Support (ATLS) course of the American College of
Surgeons )

 Single detector CT scan has a sensitivity of 98% for
fracture with a specificity of 93%
 With the new generation of 16 and up to 64 detector
scanners, it is likely that CT today is more accurate and
more cost effective
 In summary, despite the aforementioned
recommendations, CT is being used for screening
cervical spine in high-risk patients, particularly if CT is
also to be used to evaluate the subject's head
 Radiography remains appropriate in low-risk
subjects, as well as in those situations where CT is not
available.

 Only if ligamentous injury is suspected
 The AANS suggests that cervical spine immobilization
may be discontinued if “normal and adequate” flexion-
extension radiographs are obtained in an awake patient
with normal radiographs or CT in the presence of neck
pain or tenderness
 In summary, no reliable evidence exists regarding the
appropriate role for flexion-extension radiography in
the acute evaluation of cervical spine trauma.

The biomechanics of injury in the elderly differ from younger adults–
1. Osteopenia, which is ubiquitous in this population, leads to a
lower energy threshold for fracture and affects fracture location
2. Biomechanically, the spine in elderly patients is altered by
degenerative fusion usually in the lower cervical
segments, which leads to marked decrease in motion in the lower
cervical spine
3. Finally, the mechanism of cervical spine injury in the elderly is
substantially different than in younger adults with low-velocity
falls being more common in the elderly, and high-energy motor
vehicle crashes more common in younger subjects

 Fractures of the upper cervical spine, particularly C2,
are more common in subjects over 65 years of age than
in younger subjects
 In very elderly subjects (> 75 yrs), C2 fractures account
for nearly 50% of all fractures
 Injuries to the lower cervical segments become
increasingly uncommon as patients age.

 Cervical spine fractures are uncommon in children
 The injury patterns are different, with cranio-cervical
junction injuries being more prevalent in this group
 No validated method exists to identify pediatric
subjects who are of high risk for fracture

 Special consideration regarding radiation dose due to
the inherent radio-sensitivity of developing tissues in
children compared to adults
 Antero-posterior (AP) and lateral radiographs under
the age of 4
 AP, lateral and open mouth radiographs from 4 to 8
years old
 Children at 9 years of age and older are imaged with the
adult protocol. This is the approximate age at which the
fracture patterns revert to the adult patterns.
 CT is reserved for those subjects in whom an
abnormality is identified on radiography.

 More common than fractures of the cervical spine
 The majority of these fractures, however, are
pathologic fractures that occur in the elderly as a
consequence of minor trauma and due to underlying
osteoporosis
 Non-pathological traumatic fractures of the
thoracolumbar spine do occur in approximately 2% to
6% of admitted trauma patients
 The most common sites of injury are the T12 to L4

 CT reconstructions from an abdominal CT data set can be
considered an adequate substitute for thoracolumbar spine
radiographs for trauma patients
 ADV –
 obviate the need for dedicated thoracolumbar spine imaging
with radiography,
 more sensitive than radiography
 can be performed at minimal additional cost
 avoid additional radiation exposure
 The current rapid evolution of multidetector CT scanners
with increased numbers of detectors and higher spatial
resolution is expected to increase accuracy of such
reconstructions

ADV –
 readily available in all emergency centers
 can be performed with portable and fixed equipment
 the standard initial “screening” examination
 Cross-table lateral radiographs - inadequate to exclude
cervical spine injury, incomplete visualization of the
cervicothoracic and cranio-cervical junctions
 Oblique views - although useful in patients with unilateral
locked facet, are most valuable in adding two more views of
the cervico-thoracic junction in patients with equivocal
lateral that are not undergoing CT examination (low
risk, obese short-necked patients)

 Flexion-extension radiographs are not very helpful in
the acute setting because muscle spasm in acutely
injured patients precludes an adequate examination
 Flexion-extension radiographs are helpful for ensuring
that minor degrees of anterolisthesis or retrolisthesis
in patients with cervical spondylosis are fixed
deformities

ADV over single slice CT –
 faster acquisition of a volumetric data set
 Motion and mis-registration artifacts are minimized
 high-quality reconstructed images can be obtained
 Horizontal fractures that are oriented in the plane of the
scan, such as transverse odontoid fractures, may not always
be demonstrated by single CT without MPR (Sag and Cor)
 CT may reveal more fractures than plain films and may
allow evaluation of the cervicothoracic and cranio-cervical
junctions, areas traditionally poorly visualized on plain
films

 Three-dimensional (3D) CT software programs
transform existing axial CT data into a 3D rendering of
the portion of the spinal skeleton being examined
 3D CT reformations do not reveal a significant number
of unsuspected traumatic lesions but they do provide
improved definition and comprehension of the extent
and nature of detected injuries

Advantages of 3D CT imaging includes:
 (a) ability to synthesize multiple 2D image
information, especially in areas with complex anatomy,
 (b) visualization of complex injuries presenting
vertebral rotation or dislocation and loss of alignment,
 (c) a more comprehensive assessment of cases requiring
surgical planning, and
 (d) better demonstration of displaced fractures.

 Surface rendering
 Maximum Intensity Projection (MIP)
 Volume rendering

Maximum Intensity Projection (MIP)

1 – Anterior spinal line
2 – Posterior spinal line
3 – Spino-laminar line

Laminar Space –
Distance from
posterior aspect of
articular pillars (1)
to the spino-
laminar line (2)
• Used to indicate
rotational injuries
of the cervical spine
• Injury is suggested
when there is abrupt
alteration of the
space between
adjacent levels
Laminar Space

Yellow line – pre-vertebral space (C2 <6 mm and C6 <20
mm in adults and C6 < 14 mm in children)
Black line – smooth contour
White arrow – Bulge due to anterior tubercle of atlas

Spinolaminar line –
 Any displacement in this line may be an indication of subtle traumatic vertebral
injury/dislocation.
 A line drawn through C1- 3 spinolaminar lines should intercept the C2
spinolaminar line.
 A displacement of the C2 spinolaminar line of more than 2 mm, compared with a
line drawn between the spinolaminar lines of C1 and C3, is abnormal.

Basion dental interval (BDI) -
the basion (white dot) should lie
within 12 mm of the top of the
odontoid process
The basion-axial interval (BAI) -
the PAL (white line) should lie
within 12 mm of the basion

Basion dental interval The basion-axial interval
Normal < 12 mm

 Concept initially evolved from a
retrospective review of thoracolumbar
spine injuries and observation of spinal
instability, it has also been applied to the
cervical spine.
 The posterior column consists posterior
ligamentous complex.
 The middle column includes the
posterior longitudinal ligament, posterior
annulus fibrosus, and posterior wall of
the vertebral body.
 The anterior column consists of the
anterior vertebral body, anterior annulus
fibrosus, and anterior longitudinal
ligament.
Three-column concept of the spine
(Denis)

Anterior Atlanto-dental
interval (AADI)
 does not normally
exceed 3 mm in
adults and 5 mm in
children
• In adults, because of maturity of the transverse atlantal ligament, the AADI
remains constant in flexion and extension.
• In infants and children until the age of approximately 8 years, the AADI varies
in width in flexion and extension.

Diameter of the spinal canal
 Difficulties in making accurate
measurements secondary to
differences in magnification or
focal spot-film distance.
 This problem can be overcome by
comparing the AP width of the
canal with that of the vertebral
body (canal / body)
 The normal ratio of the spinal
canal (white arrow) to the
vertebral body (black arrow) is 0.8
or more.

The normal atlanto-axial articulation in open- mouth
odontoid view
 The lateral margins of the lateral atlanto-axial joints
are symmetric and are on essentially in the same
vertical plane, plus or minus 1 mm.

 The joints of Luschka (Unco-
vertebral joints) including the
uncinate processes should be
symmetrically and vertically
aligned at all levels.
 The lateral cortical margins of
the lateral columns, which
represent the lateral cortex of
the anatomically superimposed
articular masses, appear as
smooth and gently
undulating, intact linear
densities without disruptions

 The apophyseal joints are
normally angled
approximately 35 degrees
caudally
 Normal facet joints are
oriented on axial CT
examination so that they
resemble the sides of a
“hamburger bun”

 The anterior arch (red line in B) represents the anterior cortices of the axis pedicles.
 The superior arc (yellow line in B) is a composite shadow produced by the cortex of
the notch at the base of the dens and that portion of the superior articulating
facets tangent to the central x-ray beam.
 The posterior arc (green line in B) is formed by the posterior cortex of the axis body
(posterior axial line).
 The “ring of C2” has a normal interruption at the inferior aspect (white arrow) due
to the foramen transversarium.

Location -
 Upper cervical injuries - include injuries to the base of
the skull (including the occipital condyles or
C0), C1, and C2.
 Lower cervical injuries (sub-axial) - include injuries
from C3 through C7

 Vector forces –
Flexion
Flexion-rotation
Lateral flexion
Extension
Extension-rotation
Vertical compression

 When assessing stability in the spinal column, the
three-column theory of Denis suggests that if two
columns have failed, the spinal column is unstable.

 OCF are rare, being found at postmortem examination
in 1% to 5% of patients who had sustained trauma to
the cervical spine and head
 Clinical manifestations of OCF are highly variable
 Not typically shown with conventional radiography

Plain film findings:
Difficult diagnosis due to overlapping of the bony
structures of the face, upper cervical spine, and skull
base.
 May be visible in open-mouth views that include the
condyles
 OCF are readily identified on axial or coronal
reformatted CT

Anderson-Montesano classification system (for
OCF):
 ▪ Type I: Loading fracture of the occipital condyle, typically
comminuted and in a vertical sagittal plane, but where there
is no fracture displacement or associated craniocervical
instability.
 ▪ Type II: Skull-base fracture that propagates into one or both
occipital condyles
 ▪ Type III: Infero-medial avulsion fracture of the condyle by
the intact alar ligament, with medial displacement of the
fragment into the foramen magnum. Type III OCF are
considered potentially unstable because of an avulsed alar
ligament

UNSTABLE:
 ▪ Occipital condyle fragment displacement >5 mm
 ▪ Occipito-atlantal dislocation
 ▪ Bilateral occipital condyle fractures

 Atlanto-occipital dislocation (AOD) is an uncommon
injury that involves complete disruption of all ligamentous
relationships between the occiput and the atlas
 Stability and function of the atlanto-occipital articulation
are provided by the cruciate ligament, tectorial
membrane, apical dental ligament, and paired alar
ligaments, as well as the articular capsule ligaments
 Death usually occurs immediately from stretching of the
brainstem, which can result in respiratory arrest

There are three principal forms of traumatic atlanto-
occipital dislocation -
 The first and the most common pattern is an anterior
and superior displacement of the cranium relative to C1.
 The second is a pure superior displacement (distraction)
of the cranium.
 The third, and least frequent, is a posterior dislocation
of the cranium in relation to the spine

 The lateral cervical spine radiograph is most likely to
reveal the injury
 Sagittal CT reconstructions or sagittal magnetic
resonance imaging (MRI) can allow for the diagnosis
when plain radiography is inconclusive.
• >12 mm Basion Dental distance
• Separated occipital condyle and superior
surface of C1
Atlanto-occipital Distraction

 Generally related to axial loading
 Neurologic compromise is relatively infrequent with
fractures of the C1 ring, presumably because the axial
compression mechanism results in a burst
configuration with expansion of the spinal canal
 Jefferson Fracture
 Lateral Mass (C1) Fracture
 Isolated Fractures of C1

 Classically, a four-point injury with fractures occurring at the
junctions of the anterior and posterior arches with the lateral
masses, the weakest structural portions of the atlas
 Most commonly there are two fractures in the posterior arch
(one on each side) and a single fracture in the anterior arch,
off the midline
 Mechanism - A JF is created by sudden and direct axial
loading on the vertex.
The lateral articular masses of the atlas become compressed
between the occipital condyles and the superior articular facets
of the axis. By its nature, this is a decompressive injury because
the bony fragments are displaced radially away from the neural
structures

Open-mouth odontoid view -
▪ Bilateral offset or spreading of the lateral articular masses of C1 in
relation to the apposing articular surfaces of C2
▪ It is often difficult to visualize the lines of fracture per se
Lateral view: (difficult diagnosis on the lateral view)
▪ Occasionally, the fractures are demonstrated on the lateral
projection (usually the posterior arch fracture)
▪ Increase in the atlanto-axial distance (>3 mm)
▪ Anterior or posterior displacement of the C1 spino-laminar line
▪ The retropharyngeal soft tissue may be abnormal in both contour
and thickness
AP view:
▪ Usually not visible on AP cervical spine radiograph

UNSTABLE (on radiography ):
 It has been suggested that the degree of offset
distinguishes between stable and unstable Jefferson's
fractures. An unstable JF is one in which the transverse
ligament is disrupted.
▪ Total C1 lateral masses offset of both sides > 7 mm
(adding the amount of lateral displacement of each C1
lateral mass)
▪ Increase in the atlantoaxial distance (>3 mm)

 Axial images:
▪ Identify and establish the sites and number of C1 ring
fractures
▪ Establish separation between fracture fragments of the
atlas, if >7 mm the lesion is considered unstable
 Coronal reconstruction:
▪ Assess offset or spreading of the lateral articular masses of C1
in relation to the apposing articular surfaces of C2
 Sagittal reconstruction:
▪ Assess increase in the atlanto-axial distance (>3 mm) and
anterior or posterior displacement of the C1 spino-laminar line


An unstable JF is one in which the transverse ligament is disrupted.
 Coronal reconstructions:
▪ Total C1 lateral masses offset of the two sides in excess of 7 mm
(adding the amount of lateral displacement of each C1 lateral mass)
 Sagittal reconstructions: Increase in the atlantoaxial distance (>3
mm)
 Axial views: >7 mm separation between fracture fragments of the
atlas
▪ Because multilevel fractures (C1 and C2) are considered unstable, a
cautious search for contiguous fractures is critical

Atypical Jefferson fracture
 Axial CT images show a displaced (>> 7
mm suggesting instability) single fracture
of the left anterior arch of C1 (white
arrows) and left lateral comminuted
fracture of the posterior atlas ring (black
arrows).
 Avulsed fragments from the medial
surface of the left lateral mass of C1 are
noted (open arrowhead).

 Usually occur as a result of a lateral tilt
 May be limited to the lateral mass of C1, or more
commonly, occurs in association with occipital condyle
fractures and/or fracture of the articular process of C2
 Usually visible on the open-mouth view
 However, sometimes the abnormal cervico-cranial
prevertebral soft tissue contour is the only sign of injury in
plain films
 A fracture of the lateral mass of C1 is considered unstable

 usually stable
 should be distinguished from the Jefferson bursting fracture
and its variants
 The most common isolated fracture of C1 is a bilateral vertical
fracture through the posterior neural arch
 Carries no risk of neurologic deficit
 This fracture must be distinguished from developmental
defects

Isolated fracture of posterior arch smooth margins of a partially
non-ossified posterior atlas
ring

 Approximately 25% are hangman fractures, over half
(58%) are odontoid fractures, and the remainder are
miscellaneous fractures involving the body, lateral
mass, or spinous process
 Hangman Fracture (Traumatic Spondylolisthesis of
C2)
 Odontoid Fractures
 C2 Lateral Body Fractures

 Injury is identical to that created by judicial hanging and thus the
designation of the hangman fracture
 Mechanism –
 most common form of this injury results from extension combined with
axial loading
 The full force of acute hyperextension of the head on the neck is
transmitted through the pedicles of C2 onto the apophyseal joints. The
weakest points in this chain are the interarticular segments of the
pedicle. Thus, the arch of C2 is fractured anterior to the inferior facet
 Hangman fracture is a bilateral fracture through the pars interarticularis
of C2
 The pars interarticularis is found between the superior and inferior
articular processes of C2
 Spinal cord damage is uncommon, despite frequent significant fracture
displacement, due to the wide spinal canal at this level

 Lateral view: The fracture usually is diagnosed readily on the lateral radiograph in
>90% of cases unless non-displaced.
▪ Prevertebral soft tissue swelling or hematoma, often absent
▪ Fractures are often anterior to the inferior facets. They are oblique, extending from
superior/posterior to inferior/anterior
▪ Positive axis ring sign, which will show posterior ring disruption from atypical
fractures extending into the posterior C2 vertebral body cortex
▪ “Fat C2 sign”
▪ Posterior displacement of the C2 spino-laminar line of >2 mm,
▪ An avulsion fracture of the anterior margin of the axis or anterior superior margin at
C3 is often present and identifies the site of rupture of the anterior longitudinal
ligament
 AP view: Usually not visible on AP cervical spine radiograph.

CT is valuable to exclude or verify fracture line extension into the vertebral
foramina or vertebral body, or to detect subtle concurrent adjacent injuries.
 Axial images:
▪ Identify the sites of C2 ring fractures and extension into the vertebral
foramina or vertebral body.
▪ Establish separation between fracture fragments of the pars inter-
articularis of C2
 Coronal reconstruction:
▪ Usually provides no additional information as to the nature of the
hangman fracture, but can be valuable to detect concurrent adjacent
injuries.
 Sagittal reconstruction:
▪ Assess the fractures lines and posterior displacement of the C2
spinolaminar line ▪ Assess C2-3 disc space
▪ Establish separation and angulation between fracture fragments of the pars
interarticularis of C2

UNSTABLE:
▪ More than 3 mm of fragment displacement or >15-
degree angle at the fracture site
▪ Abnormal C2-3 disc space
▪ C2-3 dislocation
▪Because multilevel fractures (C1 and C2) are considered
unstable, a cautious search for contiguous fractures is
critical.

 Type I fracture - an isolated “hairline” fracture, with <
3 mm fragment displacement, < 15-degree angle at the
fracture site, and normal C2-3 disc space
 Type II injuries - > 3 mm of fragment displacement or
more than a 15-degree angle at the fracture site and an
abnormal C2-3 disc space
 Type III consists - changes that characterize type II
injury + C2-3 articular facet dislocation

Classification of dens fractures (Anderson and D'Alonso ) -
based upon the location of the fracture site with respect to
the dens
 Type I - an oblique fracture of the superior lateral aspect
of the dens, avulsed by the alar (“check”) ligament; this is
an extremely uncommon injury, occurring in < 4% of
odontoid fractures
 Type II - fracture at the base of the dens (most common -
comprising 60% of dens fractures )
 Type III - an oblique fracture of the superior portion of the
axis body caudal to its junction with the base of the dens

The radiologic diagnosis of odontoid fractures usually is established
using the lateral cervical and open-mouth odontoid view radiographs.
Open-mouth odontoid view:
 Type II odontoid fractures - transverse or oblique transverse fracture
through the lower portion of the dens.
The transverse fracture at the base of the dens must be differentiated
from a developmental abnormality termed as os odontoideum.
Os odontoideum is rounded, has a cortical margin around its
entire surface, and is usually more widely separated from the base of
the odontoid than a fracture, and with smooth margin.
Nonunion odontoid fractures may be impossible to distinguish from an
os odontoideum.

Lateral view: (Difficult diagnosis on the lateral view)
 Minimal displacement often precludes demonstration of the
fracture line.
 Positive axis ring sign will show posterior or anterior ring
disruption in type III fractures
 Type III fractures are almost always better visualized on the lateral
projection and may not be evident on the anteroposterior view
 Anterior or posterior displacement of the C2 spinolaminar line of
>2 mm
 “Fat C2 sign” in type III fractures

 If the odontoid fragment is displaced by >5 mm, a 75%
nonunion rate results
 Odontoid fracture with anterior or posterior displacement
of the C2 spinolaminar line of >2 mm
 Multilevel fractures (C1 and C2) are considered unstable
 Odontoid fractures with atlanto-axial dissociation.

 An isolated C2 lateral body fracture is rare
 is usually found incidentally when evaluating for other C2
traumatic pathology
 If a C2 lateral body fracture is found, other C-spine
pathology must be sought (ipsilateral occipital condyle, C1
lateral mass, and lower cervical spine fractures)
 Mechanism - axial compression with concomitant lateral
bending
 Radiographic findings include - impaction of the C2
component of the atlantoaxial articulation surface,
asymmetry of C2 lateral body height, and lateral tilting of
the arch of C1. Atlanto-occipital and atlantoaxial
dissociation can be seen

 Defintion - Acute traumatic atlanto-axial dissociation
(AAD) is a rare injury in which there is partial
(subluxation) or complete (dislocation) derangement of
the lateral atlantoaxial articulations
 Certain congenital conditions can be associated with
AAD, including Down syndrome, osteogenesis
imperfecta, neurofibromatosis, Morquio
syndrome, spondyloepiphyseal dysplasia congenita, and
chondrodysplasia punctata.
 Neurologic symptoms occur when the spinal cord is
involved

 The three mechanisms of AAD - are flexion
extension, distraction, and rotation.
 The most common abnormalities involve the
transverse ligament or odontoid process

 Type I AAD: AAD with rotatory fixation without anterior displacement
of the atlas.
The odontoid acts as the pivot and the transverse and alar ligaments are
intact.
This is the most common type of rotatory fixation and occurs within the
normal range of rotation of the atlanto-axial joint
 Type II AAD: Rotatory fixation with < 5 mm of anterior displacement of
the atlas. This is the second most common type and is associated with
deficiency of the transverse ligament.
 Type III AAD: Rotatory fixation with > 5 mm of anterior displacement
of the atlas. This degree of displacement implies deficiency of the TAL .
 Type IV AAD: Rotatory fixation with posterior displacement of the
atlas. This is the most uncommon type and occurs with deficiency of
the dens, such as in type II odontoid process fractures or unstable os
odontoideum (congenital or posttraumatic).

Atlantoaxial rotatory subluxation associated
with left lateral mass of C1 fracture
A: shows rotation of C1 to the right.
B: fracture of the left lateral mass of C1
C: asymmetry of the lateral atlanto-dental spaces
(black arrows) and a difference in the atlantoaxial
joint spaces (white arrows) secondary to
rotational malalignment. Increased transverse
diameter of the left lateral mass of C1 (black dot)
and truncated appearance on the right (white
dot) indicate rotation of C1 to the right.

 Anterior translation of C1
evidenced by the
abnormally wide (>> 5
mm) anterior atlanto-
dental interval (AADI)
 Anterior position of its
spinolaminar line (yellow
line in B) with respect to
that of C2-3 spinolaminar
lines

 Atlanto-axial rotational injury must be distinguished from
torticollis
 Torticollis, or “wry neck,” is more precisely defined as “acute
rotational displacement” and may be due to a variety of conditions
 It is clinically manifested by simultaneous lateral tilt and rotation
of the head
 The causes of torticollis can be subdivided in two groups –
o Disorders of rotation of the atlantoaxial joint resulting in fixed or
limited rotation of the neck. This may occur
spontaneously, secondary to trauma, or in association with
congenital anomalies or arthritides.
o Other disorders causing limited rotation of the neck without
primarily involving the atlantoaxial joint, where the primary
abnormality is in the sternocleidomastoid muscle (congenital
fibrosis, lymphadenitis, tumors of the cervical spine, painful neck).

 Rotatory subluxation is sometimes observed after upper
respiratory infection or after head and neck surgery.
 ‘Grisel syndrome’ is the occurrence of atlanto-axial
subluxation (AAS) in association with inflammation of
adjacent soft tissues.
 Torticollis is usually self-limited and occurs mainly in
children to young adolescents. The symptoms usually
disappear in 4 to 5 days.
 Most cases resolve spontaneously, although in a few
instances the rotatory deformity becomes fixed and
irreducible. The fixation usually occurs within the
normal range of rotation of the atlanto-axial joint.

 Case of torticollis due to congenital fibrosis of sternocleidomastoid
 History helps in differentiating Torticollis from traumatic AAR

 Flexion Injuries –
Clay-shoveler fracture, Anterior Subluxation , Simple Wedge
Compression Fracture, Flexion Teardrop Fracture
 Flexion rotation injuries -Unilateral Facet Dislocation
 Extension injuries – Dislocation, Extension teardrop fracture,
Laminar fractures
 Extension rotation – pillar fracture
 Vertical Compression - Burst Fracture

 Avulsion injury of the spinous process of C6, C7, or T1 (in
order of frequency).
 The fracture results from abrupt flexion of the head and
neck against the tensed ligaments of the posterior aspect of
the neck
 The name is derived from the cervical spine injury sustained
by Australian clay miners
 Posterior longitudinal ligament remains intact
 The typical clay-shoveler fracture is both mechanically and
neurologically stable.

 Occurs when posterior ligamentous complexes (nuchal
ligament, capsular ligaments, supraspinous and infraspinous
ligaments, ligamenta flava, posterior longitudinal ligament)
rupture and a minor tear of the annulus posteriorly
 The anterior longitudinal ligament remains intact.
 No associated bony injury is seen.
 Mechanism - Anterior subluxation is caused by a
combination of flexion and distraction.
 Anterior subluxation is considered clinically significant
because of the morbidity associated with the 20% to 50%
incidence of failure of ligamentous healing or “delayed
instability.”

Lateral view:
The findings of AS seen in neutral position become exaggerated upon
flexion and are reduced in extension
 Abrupt hyperkyphotic angulation at the level of ligamentous injury
 Widening of the interspinous distance at one level (“fanning”), relative to
adjacent levels
 Incongruity and lack of parallelism of the contiguous facets
 Disc space is widened posteriorly and narrowed anteriorly
 Small anterior superior compression fractures of the subjacent vertebral
body
 Increased thickness of the prevertebral soft tissues as a result of
hematoma formation

AP view:
 Widening of the interspinous distance. This sign
represents the “fanning” seen on the lateral
radiograph.
 Lateral dislocation (also called lateral translation) may
occur without significant anterior or posterior
displacement.


UNSTABLE:
 ▪Anterior translation of the vertebral body >3.5 mm
relative to the subjacent vertebra
 Vertebral body angulation >20 degrees relative to the
adjacent vertebra.

 Mechanism - result of compression of the anterior aspect
of the vertebral body
 Loss of vertebral body height, predominantly anteriorly
 The simple wedge fracture is characterized radiographically
by an impaction fracture of the superior endplate of the
involved vertebral body while the inferior endplate remains
intact
 The simple wedge fracture is considered mechanically
stable.

 Extreme form of anterior subluxation
 Ligamentous disruption and significant anterior
displacement of the spine at the level of injury
 It usually occurs in the lower cervical spine
 The spinal canal is severely compromised by this
displacement, and spinal cord injuries are frequent
 MRI is the modality indicated for subsequent imaging of
patients with BFD as it best assesses the nature and extent of
spinal cord injury as well as any associated disc and
ligamentous injury

Lateral view:
 Displacement of >50% of the antero-posterior diameter of the
vertebral body
 Dislocation of articular facets
 Narrowing of the disc space at the injured level
 Dislocation may be incomplete (perched facets), with varying
degrees of antero-listhesis of facets of one body relative to
another..
 Increased thickness of the pre-vertebral soft tissues secondary to
hematoma formation.
AP view:
 Increased inter-spinous distance at the level of dislocation.

Anterior subluxation
< 25 %
Unilateral facet
dislocation
25 – 50 %
Bilateral facet
dislocation
>> 50 %

CT findings:
CT is valuable for detection of radiographically occult
fractures of the posterior arch or articular facets.
Axial images:
 Fractures undetectable at plain radiography may be
revealed.
 “Reverse hamburger bun” sign is useful in establishing a
diagnosis of facet dislocation
 “Naked facet sign”: refers to the CT appearance of
uncovered articulating processes. On axial CT
images, there are bilateral solitary non-articulating
facets with loss of the joint space

Bilateral facet dislocation – Double vertebral body sign

 represents the most severe injury of the cervical spine
 highly unstable injury
 typically involving the lower cervical spine (especially C5)
 there is also complete disruption of all soft tissues at the level
of injury, including the posterior longitudinal
ligament, intervertebral disc, and anterior longitudinal
ligament
 typical large triangular fracture fragment of the
anteroinferior margin of the upper vertebral body (teardrop
fragment)
 The flexion teardrop fracture can be distinguished from the
similarly named hyperextension teardrop fracture by the
larger size of the triangular fragment and by distraction of
the posterior elements (indicating the flexion mechanism).

 most often encountered in elderly patients with severe
spondylosis or with spinal ankylosis from other etiologies
 Mechanism - In hyperextension fracture dislocation the
posterior spinal elements experience impaction
forces, producing loading fractures of the articular
pillars, posterior vertebral body, laminae, spinous
process, or pedicles
 Characteristically, the spine above the level of injury is
posteriorly displaced (retrolisthesis), the intervertebral disc
space is widened anteriorly and narrowed posteriorly and
the facet joints are disrupted

Plain film findings: Cervical hyperextension injuries often show minimal
radiographic abnormalities, even with severe or unstable lesions. The momentary
posterior displacement of the involved vertebra is usually completely reduced when
the causative force disappears.
Lateral view:
 Prevertebral soft tissues
 Avulsion fracture fragment from the anterior aspect of the inferior endplate of the
superior vertebra. The transverse dimension of the avulsed fragment exceeds its
vertical height (c/w flexion tear drop fragment)
 Normally aligned vertebrae.
 Anteriorly widened disc space.
UNSTABLE:
 ▪ Hyperextension dislocation is mechanically unstable.

 The spinal canal size in the thoracic region averages 16
(AP) by 16 mm (trans), whereas in the lumbar spine the
canal averages 17 (AP) by 16 mm (trans)
 Thoracolumbar junction is a region of transition and
accounts for a greater propensity for injuries in this
region - 2/3rd of all thoracolumbar fractures occur at
T12, L1, or L2
 Thoracic spinal trauma has more chances of neurological
damage because
 lumbar spine is more capacious
 cord terminating as the conus medullaris at the L1 level
 cauda equina, unlike the spinal cord, are relatively
resistant to blunt trauma

Radiologic Hallmarks of Instability in thoraco-lumbar
spine
1. Displacement/translation >2 mm, indicative of disruption to the main
ligamentous supports.
2. Widening of the interspinous space, widening of facet joints and/or
widening of the interpediculate distance.
3. Disruption of the posterior vertebral body line equates to a disrupted
anterior and posterior column or articular process fractures.
4. Widened intervertebral canal, indicative of sagittally orientated vertebral
bodytrauma.
5. Vertebral body height loss >50%.
6. Kyphosis >20 degrees.
Source: Daffner et al.

Denis – Three column theory:
Compression
Type A: Both endplates fractured
Type B: Superior endplate fracture
Type C: Inferior endplate fracture
Type D: Lateral wedging
Burst
Type A: Both endplates fractured
Type B: Superior endplate fracture
Type C: Inferior endplate fracture
Type D: Burst fracture with rotatory
component
Type E: Burst fracture with lateral
flexion
Flexion-distraction
Type A: Single level, classic Chance
fracture with bone disruption only
Type B: Single level, soft
tissue/ligamentous disruption
Type C: Two level disruption through
bone at middle column
Type D: Two level disruption through soft
tissues at middle column
Fracture-dislocation
Type A: Flexion rotations through body
Type B: Flexion rotation through disc
Type C: Posteroanterior shear injury
Type D: Posteroanterior shear injury with
floating lamina
Type E: Anteroposterior shear injury
Type F: Flexion distraction

 typical anterior wedge compression fracture
 upper and mid-thoracic spine due to the kyphotic curvature
 Neurologic instability is rare in this fracture
 Usually involves only the superior endplate
 It is distinguished from Scheuermann disease and physiologic
anterior vertebral wedging; the latter two usually involve both
superior and inferior endplate
 Bimodal distribution, occurring in the young (in the context
of high-speed trauma) and in the elderly (osteoporosis).
 Axial/burst fractures, in contradistinction, have symmetrical
reduction in height of the anterior and posterior vertebral
margins

 burst fractures of the thoracolumbar junction and
lumbar spine
 classically occurs after landing on both feet or buttocks
following a fall from a height (lover's fractures when
associated with bilateral calcaneal fractures)
 Rarely, due to seizure or electrocution

Mechanism –
 Axial compression of the vertebral body from above by the
nucleus pulposus, which explodes into the superior vertebral
endplate to result in centripetal displacement of the body
and its fracture fragments
 The retropulsion of the posterior aspect of the vertebral body
into the spinal canal is pathognomonic of a burst fracture
 As the PLL is often intact, spinal traction can reduce this
displaced fragment by tightening the PLL
 Applying the three-column principle, there is a minimum
two-column disruption (the anterior and middle) in a burst
fracture

Determinants of Burst Fracture Instability
 Widened interspinous and interlaminar distance
 Kyphosis >20 degrees
 Dislocation
 Vertebral body height loss greater than 50%
 Articular process fractures

 Posterior bowing of the
vertebral body margin
is diagnostic of an axial
compression (burst)
fracture.

 Essential to alert the clinician about the presence of a laminar split
fracture
 high association with posterior dural laceration
 Impaction of the thecal sac with the vertical fracture results in this
characteristic laceration
 The laminar split fracture almost exclusively occurs with the burst
fracture, with an incidence of 7.7% of such fractures having a
dural tear
 The presence of a dural tear requires detection prior to surgery, as
reduction of the neural extrusion and closure of the dural
laceration requires a posterior approach and should be performed
prior to any spinal reduction maneuver, which would worsen
compression of the extruded neural contents.

 Once a burst fracture is diagnosed, as with many
vertebral fractures, radiographic survey of the entire
spine is recommended as noncontiguous level
involvement may occur in as many as 6.4% to 34%
 Neurologic instability (actual or impending) has been
defined as spinal canal stenosis 50% of normal

 most common at the thoracolumbar junction
 separation in a cranial-caudal direction
 Mechanism - result of hyperflexion of the upper
thoracic spine while the lower spine remains relatively
fixed
 classically caused by a deceleration-type motor vehicle
accident

 The resultant fracture has been classically described as
the “Chance fracture”
 With the routine use of conventional three-point
restraint (shoulder harness and lap belt), the incidence
of the classic Chance fracture has decreased and burst
fractures are now more prevalent
Chance
fracture
Classic Variants

“Classic Chance fracture” :
 The classic Chance fracture accounts for approximately
50% of Chance-type injuries
 A “classic” Chance fracture - consists of a pure osseous
injury in which there is a horizontal split through the
spinous process, lamina, pedicles, resulting in a small
anteroinferior corner fracture of the lower vertebral body
 acutely unstable
 purely an osseous disruption; it also has excellent healing
potential with good prognosis for long-term stability
 Incidence of neurologic deficit is low, estimated at 10%

 AP radiographs - “double” spinous
process, interspinous distance widening, and
horizontal fractures through the pedicles
 lateral radiograph is often unreliable due to overlap
Chance variants –
 are either a combined osseous/soft tissue injury or pure
 The fracture may extend through the posterior
elements as for the classic Chance fracture, but
continues anteriorly through the disc or it may involve
the posterior ligaments and vertebral body. soft tissue
disruption.

 typically results in a severe and unstable three-column
injury, with anterior, posterior, or lateral subluxation, as
well as posterior element fracture or ligamentous
disruption
 The force vectors in this type of injury are both
enormous and complex
 neurologic impairment is frequent
 high association with thoracic and abdominal injury

 The resultant radiographic pattern is characterized by
posterior element impaction, with fractures (often
comminuted) of the spinous process, lamina, or
facets, in association with anterior disc widening or
avulsion fracture of the anterior endplate
 If severe enough, the injury may result in the
“lumberjack fracture-dislocation” in which there is
complete loss of continuity of the upper and lower
spinal segment associated with an extremely high rate
of paraplegia and dural tear

 The injury should serve as a sentinel sign, alerting one to
the possibility of other injury
 For example, an isolated L5 transverse process fracture is
commonly seen in association with a vertically oriented
sacral fracture (Malgaigne fracture/dislocation) on the
same side

Transverse process fracture
associated with a sacral
fracture

Isolated sacral fractures
are uncommon
Transverse fractures-
• most common type
• Common at S3-S4
level
• High horizontal
fractures occur from
high falls (suicidal
jumper’s fracture)
Vertical fractures –
• Usually indirect
trauma to pelvis
• Usually runs entire
scrap length

 Most are transversely oriented
 AP radiograph – not useful
 Lateral radiography – anteriorly tilted / displaced
coccyx

 The greatest impact that MRI has made in the
evaluation of SCI has been in assessment of the
intracanalicular and paraspinal soft tissues
 MRI has replaced myelography and CT myelography as
the primary imaging option to assess for compression
of the spinal cord
 An MRI examination in the acute period is warranted
in any patient who has a persistent neurologic deficit
after spinal trauma

 Requires special consideration before MRI with regard to
patient transfer, life support, monitoring of vital
signs, fixation devices, choices of surface coils, and pulse
sequences
 several manufacturers offer MRI-compatible ventilators
 MRI-compatible monitors are now available that can relay
heart rate, respiration, blood pressure, and oxygenation
information directly into the MRI control area.
 Indwelling central venous catheters with thermocouples and
conventional intravenous medication pumps are prohibited
in the MRI environment

 Currently, MRI does not offer any advantage over plain
radiography or high-resolution multidetector CT
(MDCT) in the evaluation of associated osseous
injuries following spinal trauma
Chance fracture
(GRE)

 MRI is the only imaging modality available that directly
visualizes changes to the ligaments as a result of trauma
 ligaments appear relatively hypointense to other structures
on all MRI pulse sequences
 Edema or tear - increase in signal intensity on T2-weighted
or GE images because of an increase in free water content
from extracellular fluid or adjacent hemorrhage
 Because of the similarity in imaging
characteristics, distinction between a ligament fragment
and cortical bone fragment may prove difficult on MRI

• Extensive degenerative
changes noted but no
gross evidence of
malalignment
• The ALL, LF and
PLL are disrupted.
• There is widening
of the interspinous
distance
• Edema in the
posterior paraspinal
soft tissues
• damaged
intervertebral disc

Discontinuity of the ligamentum flavum and
edema in the posterior paraspinal musculature

 Standard MR pulse sequences are typically capable of
receiving signals from tissues that have T2 relaxation
properties greater than 10 milliseconds
 However, the intrinsic T2 relaxation of ligaments is
typically <1 millisecond. This is why ligaments are of
low signal on conventional MRI.
 The typical echo times of the UTE sequence are on the
order of 0.08 millisecond and are therefore capable of
capturing signal from less conspicuous structures

 Ultrashort TE imaging of the transverse ligament of C1,
 Entire transverse ligament as a high signal intensity structure (arrows).
 The transverse ligament is usually difficult to identify using standard
clinical MR sequences.

can be classified as either disc injury or disc herniation
 Disc injury - is implied whenever there is
 asymmetric narrowing or widening of an isolated disc
space on sagittal images and
 focal hyperintensity of the disc material on T2-weighted
images
 potentially hemorrhagic MR signal changes of a
damaged disc may therefore be, in part, due to damage
to the adjacent endplates
 Disc herniation –
 similar MRI appearance to nontraumatic disc herniation

• acute angulation of C3 on C4
with spinal cord compression
• large herniated disc fragment (arrow)
compressing the spinal cord
• free edge of the ruptured PLL adjacent to
the disc fragment

 The imaging characteristics of epidural hematomas are
variable as they depend on the oxidative state of the
hemorrhage and the effects of clot retraction
 In the acute phase,
 isointense with spinal cord parenchyma on T1-weighted
images
 isointense with CSF on intermediate- and T2-weighted
sequences
 The epidural collection may be difficult to distinguish from
the adjacent CSF in the subarachnoid space.
 This distinction can often be made by the hypointense
dura, which separates the two compartments

• A large dorsal epidural hematoma is displacing the posterior
margin of the dura
• The roots of the cauda equina are compressed against the
vertebral body by the hematoma

 Investigations have suggested that damage to the
vertebral arteries can be demonstrated
angiographically in up to 40% of patients following
cervical subluxation/dislocation
 But are mostly clinically occult
 Dissection of the vertebral artery is more frequent than
carotid artery dissection following fracture/subluxation
because a portion of the cervical vertebral artery is
contained within the foramen transversarium

 MRA is an appropriate screening test to identify
patients who may require subsequent catheter
angiography
 A 2D TOF sequence is effective in screening the
extracranial vasculature for occlusion
 Resolution limits the effectiveness of detecting subtle
intimal injuries associated with dissection
 Use of black-blood techniques is advocated to improve
detection of sub-intimal dissections without occlusion

 Clinically occult
vertebral artery
thrombosis after
unilateral facet
dislocation
 3D GRE acquisition
shows an oval area of
low signal intensity
in the right foramen
transversarium
 Axial FSE image
shows a high-signal-
intensity thrombus

 The depiction of parenchymal SCI on MRI not only
correlates well with the degree of neurologic
deficit, but it also bears significant implications in
regard to prognosis and potential for neurologic
recovery
 Imaging characteristics are due to accumulation of
edema and hemorrhage within the substance of the
cord parenchyma

Spinal cord injury without
radiographic abnormality
(SCIWORA)
absence of an obvious
fracture or subluxation
edema within the spinal
cord at the C3-4 level
(arrow) and prevertebral
edema
T2-weighted MRI with
fat suppression shows
the compression of the
spinal cord

 The most common location is within the central gray
matter of the spinal cord
 Centered at the point of mechanical impact

 In the acute phase following injury, deoxyhemoglobin
is the most common species generated.
 Thus, the hemorrhagic component is depicted as a
discrete area of hypointensity on the T2-weighted and
GE images
 Detection of a sizable focus of blood (>10 mm in
length on sagittal images) in the spinal cord is often
indicative of a complete neurologic injury

 small focus of
hyperacute hemorrhage
at C1-2 (arrow) and very
subtle high-intensity
edema
Two days later, more
obvious edema
extending down to C4
and clear hemorrhage
in deoxyhemoglobin
state is
seen, particularly on
axial GRE (C), where
hemorrhage is noted
within central portion
of spinal cord

 focus of abnormal high signal intensity on T2-weighted
images
 Edema involves a variable length of spinal cord above
and below the level of injury, with discrete boundaries
adjacent to uninvolved parenchyma

 In children, fractures and severe injuries to the spine are
relatively rare
 The anatomy and biomechanics of the growing
spine, larger head size relative to body size,
 greater flexibility of the spine and supporting structures,
 incomplete ossification, as well as
 greater elasticity and compressibility of the bone,
produce failure patterns different from those seen in
adults
 Anatomic differences between the pediatric and adult
cervical spine are prominent until approximately 8 – 10
years of age

 SCIWORA is far more common in younger children than
in older children
 Pseudosubluxation –
 normal physiologic displacement of C2 on C3, and to a
lesser extent C3 on C4, can mimic the appearance of a true
cervical spine injury
 ~ 40% of children under the age of 8 demonstrate
pseudosubluxation at the C2-3 level

• Spino-laminar line displacement
within 1.5 mm of each other on
both flexion and extension
views confirms the pseudo-
subluxation
• A measurement of >2 mm is
definitely abnormal, indicating
a true injury
• Measurement of 1.6 to 1.9 mm is
considered indeterminate

 Imaging plays a pivotal role in assessing the mechanical and
neurologic stability of the traumatized thoraco-lumbar spine.
 Radiography is still preferred in low risk “reliable”
(awake, alert, normal mental status, and no significant distracting
pain) subjects.
 CT is the preferred imaging modality in subjects at high risk of
injury, however, because of higher sensitivity and specificity.
 CT, with the use of high-resolution multiplanar and 3D
reformations, has resulted in improved fracture pattern
classification with better differentiation between stable or unstable
injuries.
 MRI is still the only imaging method that demonstrates the soft
tissue components of injury and provides an objective assessment
of the damaged spinal cord's internal architecture

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