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Cervical Spine Injuries in Polytrauma Patients: What the
Surgeon Wants to Know.
Poster No.:
C-1655
Congress:
ECR 2016
Type:
Educational Exhibit
Authors:
E. Federici, C. Dell'atti, V. Martinelli, D. Beomonte Zobel, M.
Bartocci, N. Magarelli, L. Bonomo; Rome/IT
Keywords:
Education, Diagnostic procedure, CT, Conventional radiography,
Musculoskeletal spine, Emergency, Trauma
DOI:
10.1594/ecr2016/C-1655
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Page 1 of 32
Learning objectives
•
•
•
To review the spectrum of cervical spine injuries, from the craniocervical
junction through the subaxial spine.
To highlight the role of multidetector computed tomography (MDCT) for
diagnosis of cervical spine injuries in polytrauma patients.
To identify what the surgeon needs to know about the injury to predict
outcomes and plan management.
Background
Cervical spine injuries occur in 5%-10% of patients with polytrauma and it is a common
problem with a wide range of severity from minor ligamentous injury to frank osteoligamentous instability with spinal cord injury.
It is essential that radiologists recognize findings that distinguish injuries with ligamentous
instability or that require surgical stabilization from those that are classically stable and
can be treated with a conservative treatment.
Craniocervical Junction (CCJ) and Subaxial Cervical Spine
The CCJ is an anatomical region that is formed by complex articulations involving the
occipital condyles and the first two vertebra. These joints are supported by several
ligaments, including the anterior longitudinal ligament, the anterior atlantoaxial and
atlantooccipital ligaments, the cruciform ligaments, the alar ligaments, and the tectorial
membrane, which extends cranially as the cephalic extension of the posterior longitudinal
ligament (Fig1) [1]. Craniocervical biomechanical continuity depends on the integrity of
the skull base, atlas, and axis and their attaching ligaments.
Page 2 of 32
Fig. 1: Anatomy of the craniocervical region.
References: Atlas of Human Anatomy Netter.
A full conventional RADIOGRAPHIC EXAMINATION of the cervical spine as a minimum
includes a lateral view, antero-posterior (AP) view and an AP odontoid peg view. The
lateral view should include the cervical-thoracic junction.
Normal measurements have been determined for many of the bone relationships and
soft-tissue contours at the craniocervical junction and are valuable for excluding upper
cervical spine injury.
Harris et al [2,3] have identified a practical method for evaluating the normal osseous
relationships at the craniocervical junction using lateral conventional radiographs. They
determined the upper limits of normal for adults and children by measuring the basiondens interval (tip of dens to basion) and the basion-posterior axial line interval (basion to
posterior axial line, a vertical line drawn along the posterior aspect of the subdental body
of C2). In 95% of adults, the basion-dens interval was less than 12 mm, and in 98%, the
basion was situated no more than 12 mm anterior or 4 mm posterior to the posterior axial
line (Fig 2). An abnormal distance between the dens or posterior axial line and the basion
suggests failure or insufficiency of the alar ligaments, tectorial membrane, or both.
Page 3 of 32
Fig. 2: Normal relationships within the craniocervical junction: the basion-dens interval
(a), the posterior axial line (b) and the basion-posterior axial line interval (c).
References: Institute of Radiology, Catholic University - Rome/IT
Alignment is assessed by visually assessing the SPINAL LINES on the lateral radiograph
(Fig.3). They should all appear smooth and without interruption [4].
•
•
•
•
The anterior spinal line passes along anterior borders of the vertebral
bodies and the anterior aspect of the odontoid peg. The distance between
the anterior arch of C1 and the odontoid peg should not exceed 3 mm in
adults and 5 mm in children.
The posterior spinal line passes along the posterior borders of the
vertebral bodies.
The junction of the laminae with the spinous processes forms the
spinolaminar line. The lamina of C2 is normally up to 2 mm posterior to the
spinolaminar line.
The distance between the spinous processes should be roughly equal at
all levels, taking into account the normal downward slope of the C7 spinous
process.
Page 4 of 32
Fig. 3: Lateral radiograph shows normal alignment of the subaxial spinal lines: the
anterior marginal line (1), the posterior marginal line (2), the spinolaminar line (3) and
the posterior spinous line (4).
References: Institute of Radiology, Catholic University - Rome/IT
Noting the central position of the spinous processes assesses alignment on the AP
radiograph (Fig.4). The spinous processes of the cervical spine may appear bifid; this is
a normal anatomical finding at many levels and in this situation the central point of the
posterior elements is the point midway between the two tubercles of the spinous process.
Page 5 of 32
Fig. 4: Antero-posterior radiograph shows normal alignment of spinous processes.
References: Institute of Radiology, Catholic University - Rome/IT
When assessing the AP through mouth odontoid peg view (Fig.5), normal alignment
is demonstrated by noting that the lateral margins of the C1-C2 facet joints are
symmetrically aligned with no overlap.
Page 6 of 32
Fig. 5: The distance from the dens (A,3) to the lateral masses of C1 (A,2) should be
equal bilaterally. B: Open-mouth or odontoid view.
References: Institute of Radiology, Catholic University - Rome/IT
Soft-tissue swelling is assessed on the lateral radiograph. Superior to the level of the
larynx the distance between the anterior aspect of the vertebral bodies and the posterior
aspect of the air in the oropharynx should be no greater than one-third of the AP diameter
of a vertebral body width. Inferior to the level of the larynx (usually C3 or C4 and frequently
seen due to calcification in the laryngeal cartilage) it should be no greater than the AP
diameter of the vertebral body [4].
CT of the cervical spine should include the spine from the cranio-cervical junction to the
level of the third thoracic vertebral body. The precise imaging parameters will depend on
the CT system being used, but an appropriately thin slice thickness should be selected to
allow good-quality coronal and sagittal reformats. The alignment and soft-tissue swelling
is assessed on these reformats using the same basic principles as the interpretation
of the conventional radiograph. The axial sections are particularly useful for diagnosing
bone fractures.
The presence of malalignment and soft-tissue swelling will often give an indication of
ligamentous disruption in the absence of any bony injury but this is not always the case.
If there is continued clinical concern following a normal CT, then MRI is warranted as CT
cannot exclude a purely ligamentous disruption.
Page 7 of 32
Images for this section:
Fig. 1: Anatomy of the craniocervical region.
© Atlas of Human Anatomy Netter.
Page 8 of 32
Fig. 2: Normal relationships within the craniocervical junction: the basion-dens interval
(a), the posterior axial line (b) and the basion-posterior axial line interval (c).
© Institute of Radiology, Catholic University - Rome/IT
Page 9 of 32
Fig. 3: Lateral radiograph shows normal alignment of the subaxial spinal lines: the
anterior marginal line (1), the posterior marginal line (2), the spinolaminar line (3) and the
posterior spinous line (4).
© Institute of Radiology, Catholic University - Rome/IT
Fig. 4: Antero-posterior radiograph shows normal alignment of spinous processes.
Page 10 of 32
© Institute of Radiology, Catholic University - Rome/IT
Fig. 5: The distance from the dens (A,3) to the lateral masses of C1 (A,2) should be equal
bilaterally. B: Open-mouth or odontoid view.
© Institute of Radiology, Catholic University - Rome/IT
Page 11 of 32
Findings and procedure details
MDCT is used throughout major trauma centers as the initial screening examination for
high-risk patients who are suspected of having cervical spine trauma, and it is increasingly
incorporated into whole-body CT protocols in the evaluation of polytrauma. MDCT is
often sufficient for making the determination of whether surgery is necessary or not, but
important determinants of management (disk herniations, ligament injuries or epidural
hematoma) are not well evaluated with CT but are clearly depicted at MR imaging.
INJURIES OF THE CRANIOCERVICAL JUNCTION
Craniocervical Dissociation
Craniocervical dissociation is an umbrella term that describes both
•
•
complete dislocations, which are common in fatal motor vehicle trauma, and
subluxation or distraction injuries, which may be subtle and potentially
survivable.
By definition, atlanto-occipital dissociation is an unstable injury with severe ligamentous
disruption and is usually accompanied by severe neurologic deficit. Traumatic atlantooccipital dissociation is more common and more survivable in skeletally immature
pediatric trauma patients [1].
Lateral radiographic findings in atlanto-occipital distraction injuries include soft-tissue
swelling and pathologic convexity of the soft tissues anterior to C2 (generally greater than
10 mm in thickness) and a basion-dens interval greater than 12 mm in children under
the age of 13 years. [5].
Occipital Condyle Fractures (OCF)
Anderson and Montesano [6] introduced the most widely used radiologic classification
system for occipital condyle fractures, describing three different patterns of injury:
•
Type I OCF is an impaction-type fracture resulting in a comminution of
the occipital condyle, with or without minimal fragment displacement. The
mechanism of injury is believed to be axial loading of the skull onto the atlas
Page 12 of 32
•
•
with or without lateral bending. It is considered a stable entity because the
tectorial membrane and contralateral alar ligament are intact; however,
bilateral lesions may be unstable (Fig.6) [7].
Type II OCF is part of a more extensive basioccipital fracture, involving one
or both occipital condyles. The mechanism of injury is a direct blow to the
skull. An intact tectorial membrane and alar ligaments preserve stability [7]
Type III OCF is an avulsion type of fracture near the alar ligament resulting
in medial fragment displacement from the inferomedial aspect of the
occipital condyle into the foramen magnum. The mechanism of injury
is forced rotation, usually combined with lateral bending (Fig.7). After
occipital condylar avulsion, the contralateral alar ligament and tectorial
membrane may be stressed and "loaded" resulting in a partial tear or
complete disruption. Thus, the type III OCF is considered a potentially
unstable injury [7].
Fig. 6: Axial (a), coronal (b) and sagittal (c) CT images show a Type I OCF (yellow
arrows).
References: Institute of Radiology, Catholic University - Rome/IT
Page 13 of 32
Fig. 7: Axial (a) and coronal (b) CT images show a Type III OCF (yellow arrows).
References: Institute of Radiology, Catholic University - Rome/IT
Fractures of the Atlas
Jefferson introduced the first classification system for atlas fractures, which is still in use
with some modifications [8,9].
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Type I: fractures of the posterior arches alone.
Type II: isolated fractures of the anterior arch.
Type III: bilateral posterior arch fractures with unilateral or bilateral anterior
arch fracture (classic Jefferson burst).
Type IV: fractures of the lateral mass.
Type V: transversely oriented anterior arch fractures resulting from avulsion
of the longus colli or atlantoaxial ligament.
Fractures of the atlas are usually mechanically stable and rarely result in neurologic injury.
For atlas fractures, associated cervical spine fractures and the integrity of the transverse
ligament are the main determinants of the need for surgical intervention (Fig.8) [9].
Classic Jefferson fracture
Page 14 of 32
Burst fractures of the atlas are thought to result from axial loading. This bursting fracture
is the result of force transmitted from the vertex of the skull through the occipital condyles
to the lateral masses of the atlas. The fracture pattern results in outward displacement of
the lateral masses, a finding that indicates possible injury to the transverse ligament.
To prevent atlantoaxial dissociation, Jefferson fractures may require surgical stabilization
if the transverse ligament is compromised or the anterior arch is appreciably displaced.
Fig. 8: Axial CT images show a Jefferson fracture with fractures of the anterior arch
and the posterior arch (a, yellow arrows) of atlas and demonstrate the avulsion of a
bony fragment by the transverse ligament (b, yellow arrows).
References: Institute of Radiology, Catholic University - Rome/IT
Odontoid Fractures.
Odontoid fractures are classically divided into three groups (Fig.9), as introduced by
Anderson and D'Alonzo [10].
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Type I: fractures represent an avulsion fracture of the odontoid tip at the
insertion of the alar ligament. They are rare with a limited number of case
reports in the medical literature. The fracture is typically described as stable.
Type II: odontoid fractures represent the most common pattern of dens
injury and occur through the base of dens at the junction of the C2 vertebral
body (Fig.10). The fracture is traditionally considered unstable, often
requiring immediate surgical stabilization.
Page 15 of 32
•
Type III: fractures extend into the C2 vertebral body (Fig.11). Fracture
displacement is common; however, fewer than 8% of patients with Type
III fractures develop nonunion after non-surgical immobilization alone.
Thus, Class III data support halo immobilization for 6-8 weeks as a first-line
management [11].
Fig. 9: Odontoid fracture classification by Anderson and D'Alonzo.
References: Institute of Radiology, Catholic University - Rome/IT
Page 16 of 32
Fig. 10: Sagittal (a) and coronal (b) CT reformats show a Type II odontoid peg
fracture (yellow arrows).
References: Institute of Radiology, Catholic University - Rome/IT
Fig. 11: Sagittal (a) and coronal (b) CT reformats show a Type III odontoid peg
fracture (yellow arrows).
Page 17 of 32
References: Institute of Radiology, Catholic University - Rome/IT
Hangman Fractures.
A hangman's fracture is a traumatic spondylolisthesis of C2 where a fracture occurs
through both pedicles, separating the posterior elements from the vertebral body (Fig.12).
The C2 vertebral body subluxes anteriorly relative to C3 but the posterior elements
remain normally aligned. Because the spinal canal effectively widens in AP diameter at
the level of slip there is often little or no neurological injury despite sometimes marked
spondylolisthesis.[4]
These fractures can occur as the result of either compressive hyperextension or
distractive hyperflexion and can involve any part of the axis ring, including laminae,
pedicles, or part of the posterior wall of the axis body.
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Fig. 12: Axial (a), coronal (b) and sagittal CT images show a hangman fracture (yellow
arrows).
References: Institute of Radiology, Catholic University - Rome/IT
Atlantoaxial Rotatory Subluxation and Fixation
Traumatic rotatory subluxation and fixation are well documented in children but are rare in
adults [12]. Higher degrees of rotatory subluxation have a greater propensity to develop
into rotatory fixation and have a greater need for surgical reduction.
Fielding and Hawkins [13] have described a number of configurations of atlantoaxial
rotatory fixation.
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•
•
Type I: atlantoaxial rotatory fixation occurs within the normal physiologic
range, with intact alar and transverse ligaments.The dens acts as the pivot,
and there is no anterior displacement of the atlas.
In type II: atlanto-axial rotatory fixation, the transverse ligament is injured.
Anterior displacement of the atlas should not exceed 5 mm because of
restraint from the alar ligament.
In type III: atlantoaxial rotatory fixation, both the transverse and alar
ligaments are deficient. The configuration is similar to type II, but anterior
displacement of the atlas exceeds 5 mm.
Type IV: describes the rare circumstance in which a deficient odontoid is
present, resulting in posterior displacement of the atlas. The spinal canal
may be compromised in types II to IV.
INJURIES OF THE SUBAXIAL CERVICAL SPINE
Hyperflexion Injuries
Flexion forces to the spine can cause rupture of the posterior elements. Typically there
may be little in the way of anterior soft-tissue swelling since all the soft-tissue injury occurs
posteriorly. There may be a fracture of the anterior aspect of the vertebral body, the
flexion teardrop fracture. The bony fragment is typically relatively large and elongated
in the cranio-caudal direction of the spine, which distinguishes it from the hyperextension
tear drop, which is usually a small fragment. There is a strong association with severe
neurological injury [4].
Bilateral subluxation of the facet joints can occur with little in the way of bony injury. The
facet joints can lock in a displaced position, the so-called perched facet joints.
Page 19 of 32
A hyperflexion force with resistance of the posterior paraspinal muscles can produce
a 'clay-shoveler's' fracture (Fig.13). This is a fracture of the lower cervical or upper
thoracic spinous process and is one of the few cervical fractures that can be considered
stable [4].
Page 20 of 32
Fig. 13: Sagittal CT reformat shows a 'clay-shoveler's' fracture (yellow arrow).
References: Institute of Radiology, Catholic University - Rome/IT
Page 21 of 32
Hyperflexion Rotation Injury
A rotational force applied along with flexion can result in a unilateral dislocation of a
facet joint. Malalignment in the sagittal plane may be very minimal. CT demonstrates the
'reverse hamburger' sign on the axial sections through the facet dislocation [4].
Hyperextension Injuries
Extension force to the spine can result in rupture of the anterior longitudinal ligament
and posterior displacement and angulation. There is typically soft-tissue swelling
anterior to the spine at the site of the ligamentous disruption. There may be an
associated hyperextension teardrop fracture (Fig.14), which is usually a small
fragment. Neurological abnormality implies that a hyperextension dislocation occurred at
the time of injury though the spine may be relatively normally aligned subsequently [4].
Page 22 of 32
Fig. 14: Lateral radiograph shows a hyperextension teardrop fracture of C2 (yellow
arrow).
References: Institute of Radiology, Catholic University - Rome/IT
Page 23 of 32
Images for this section:
Fig. 6: Axial (a), coronal (b) and sagittal (c) CT images show a Type I OCF (yellow
arrows).
© Institute of Radiology, Catholic University - Rome/IT
Page 24 of 32
Fig. 7: Axial (a) and coronal (b) CT images show a Type III OCF (yellow arrows).
© Institute of Radiology, Catholic University - Rome/IT
Fig. 8: Axial CT images show a Jefferson fracture with fractures of the anterior arch and
the posterior arch (a, yellow arrows) of atlas and demonstrate the avulsion of a bony
fragment by the transverse ligament (b, yellow arrows).
Page 25 of 32
© Institute of Radiology, Catholic University - Rome/IT
Fig. 9: Odontoid fracture classification by Anderson and D'Alonzo.
© Institute of Radiology, Catholic University - Rome/IT
Page 26 of 32
Fig. 10: Sagittal (a) and coronal (b) CT reformats show a Type II odontoid peg fracture
(yellow arrows).
© Institute of Radiology, Catholic University - Rome/IT
Page 27 of 32
Fig. 11: Sagittal (a) and coronal (b) CT reformats show a Type III odontoid peg fracture
(yellow arrows).
© Institute of Radiology, Catholic University - Rome/IT
Fig. 12: Axial (a), coronal (b) and sagittal CT images show a hangman fracture (yellow
arrows).
© Institute of Radiology, Catholic University - Rome/IT
Page 28 of 32
Fig. 13: Sagittal CT reformat shows a 'clay-shoveler's' fracture (yellow arrow).
© Institute of Radiology, Catholic University - Rome/IT
Page 29 of 32
Fig. 14: Lateral radiograph shows a hyperextension teardrop fracture of C2 (yellow
arrow).
© Institute of Radiology, Catholic University - Rome/IT
Page 30 of 32
Conclusion
In the emergency department, accurate diagnosis of cervical spine fractures by the
radiologist working closely with the orthopaedic is crucial for ensuring prompt and
effective treatment and preventing neurologic deficits in polytrauma patients.
Personal information
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11. Julien TD, Frankel B, Traynelis VC, Ryken TC. Evidence-based analysis of
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