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 Introduction
Despite of the fact
that the role played by the medical and
paramedical personnel caring for the
acutely injured comes late after the
injury has occurred, there remain several
avenues through which help could be
provided to minimise the aftermath of the
injury. A true example of this is
illustrated in rationally caring for and
clearing of the cervical spine after
trauma. In this context, this article
reviews the current medical literature
pertinent to cervical spinal clearance.
Although there aren't
many evidence-based practice standards for
clearing the cervical spine after trauma,
an agreed-upon guidelines protocol could
still be generated that can secure the
safe-handling and clearance of the spine
in the acutely injured. The role of
various radiographic modalities is
presented in this article and radiological
versus clinical clearance procedures are
discussed and summarised in an algorithm
chart (see
page 2).
I believe the implementation of these
guidelines in hospitals and trauma centres
in our part of the world would enhance the
care of trauma patients. Indeed, that has
been our experience following the
launching of a pocket-size cervical spine
clearance guidelines-booklet in Hamad
General Hospital 18 months ago.
Background
Injury to the spinal
cord has potentially devastating
consequences that may reach far beyond the
precincts of the victim, and his family
and friends, to affect the community in
general should the patient encounter long
term neurological sequelae. Instead of
being an active participant in the
creation and maintenance of his community's
prosperity, the injured person,
incapacitated with neurological physical
disability, becomes a burden on his
community. Income loss and healthcare
expenditure incurred in the provision of
lifelong care of the paralysed are
examples of the socioeconomic
ramifications of spinal injuries.
An important factor
that influences the management outcome of
acute spine and spinal cord injuries is
the way patients are handled immediately
following trauma during the phases of
resuscitation, transfer and acute
treatment.
The sequences of
primary impact and secondary insults to
the spinal cord may not be typical of the
pathomechanisms involved in traumatic
brain injury.(1,2)
It is comprehensible
that an intact or mildly injured spinal
cord could be secondarily damaged by
erroneous handling of a patient with an
unstable spinal fracture. Negligence in
spinal stabilization risks neurological
damage, which remains as long as the spine
remains unstable. Indeed, it has been
estimated that up to 25% of spinal cord
injuries in trauma patients occur
secondary to insults encountered during
the patient transfer, or at the time of
initial resuscitation and early phases of
management.(3,4,5,6,7,8)
There has been a
noticeable improvement, however, in the
neurological condition and outcome of
trauma patients during the past 3 decades.
This has resulted from the practice of
prehospital resuscitation and spine
immobilization at the scene of the
accident following the development of the
emergency medical services (EMS) system in
the early 1970s.(9,10,11,12)
Missing
cervical spine injuries
Being the most exposed, most mobile and
least protected segment of the spine, the
cervical spine is more prone to injuries
that can result in a most devastating
incapacitation in form of life-long
quadriplegia and ventilator dependency.
Although the overall incidence of cervical
spinal injury is low in the general
population of trauma patients, missing
such injuries could be detrimental
and might raise allegations of medical
negligence.(13)
There are several
causes for missing a cervical spinal
injury, which include:
1.
Failure to suspect
the injury.
2. Failure to request
radiographs.
3. Inadequate or
suboptimal quality of radiography.
4. Incorrect
interpretation of the x-rays.
The most common
levels missed are the upper and lower ends
of the cervical spine; i.e. the
craniovertebral and cervicothoracic
junctions respectively.(14,15,16)
Efforts have hitherto continued to coin
management guidelines that can help
minimise the chances of missing a cervical
spine injury. In order to be effective and
efficient, a guidelines protocol for
cervical spine clearance ought to be safe,
simple, robust, cost-effective and, at the
same time, easy to implement within the
set up of trauma services in a particular
geographical location. Several protocols
have been reported. These have been
reviewed in a comprehensive coverage of
the management of acute cervical spine
injuries that has been recently published
by the American Association of
Neurological Surgeons (AANS) and Congress
of Neurological Surgeons (CNS) Joint
Section on Disorders of the Spine and
Peripheral Nerves.(17)
Spinal
immobilization
As a general rule,
resuscitation and lifesaving procedures
take precedence over spinal clearance in
the early phases of management of the
acutely injured. Trauma victims,
particularly the high risk patients who
are involved in high-speed motor vehicle
accidents or falls from significant
heights (more than 10 feet), must be
handled cautiously and treated as if they
have had sustained unstable spinal
injuries. At this stage, spinal imaging is
deferred and spinal immobilization is
maintained until spinal injuries are
excluded or a definitive treatment plan is
set up. Multilevel noncontiguous spinal
fractures are reported to occur in 1.6% to
16.7% of spinal injury
cases.(18,19,20,21) Hence, it has been recommended that
the entire spine is immobilised until the
process of clearance is completed.
Several methods of
cervical spinal immobilization are used in
different centres and there has not yet
been a practice standard for an optimal
device. The long standing practice of
spinal immobilization using sandbags and
tapes alone is no longer
recommended.(22) The American College of Surgeons
have proposed the combined use of a hard
backboard, a semirigid neck collar,
lateral supports, and straps to immobilize
and secure the entire body to the board.
This time-tested practice has been
endorsed in the Advanced Trauma Life
Support (ATLS) teachings
worldwide.(23) Though it is crucial to immobilize the
spine in the acutely injured as outlined
above, it has to be noted that spinal
immobilization devices are not without
complications. Unduly prolonged
immobilization of a patient on a hard
backboard and the application, for a long
period, of a tight-fitting hard neck
collar can cause skin breakdown. The use
of the latter has also been argued to
exacerbate raised intracranial pressure in
cases of severe traumatic brain
injury.(24,25)
In order to minimise
these complications, the spine should be
cleared, or otherwise, a treatment plan
for spinal injury initiated as soon as
feasible.
Radiological
clearance of the cervical spine
Spinal imaging should
serve the purpose of fully delineating
evidence of traumatic injury to all
elements of the spine. An ideal imaging
modality would thus be able to reveal
bony, spinal cord and ligamentous
injuries, in addition to other traumatic
lesions, like disc rupture and
haematoma. Such an imaging tool has yet to be
invented and so far neither of the
available imaging modalities is capable of
depicting all of these injuries. Moreover,
none is accurate 100% of the time.(17)
It
has been reported that plain x-ray films
show no evidence of trauma in up to 14% of
spinal cord injuries in adults, while
computed tomography (CT) scan can miss
around 5% of cases.(26,27) The
combination of three-view cervical spine
x-rays with targeted CT scanning, on the
other hand, would pick the vast majority
of cervical spinal injuries.
A complete
radiographic evaluation of the cervical
spine entails visualization of the spine
from the base of the occiput through T1.
It is imperative that the imaging quality
is sufficiently adequate to address the
objectives of radiological assessment.
Following that, the systematic reading and
interpretation of the radiographs by an
experienced physician (be this a
radiologist, A&E specialist, neurosurgeon
or orthopaedic surgeon) can not be
overemphasized. The guidelines for x-ray
identification of spinal injuries included
in the ATLS manual serve this purpose.(23)
Several
imaging modalities have been used, mostly
in combination, in the radiological
assessment of symptomatic trauma patients.
Those most commonly utilised are plain
x-rays, computed tomographic (CT) scans,
magnetic resonance image (MRI) scans and
fluoroscopy. The role of each is reviewed
below.
Plain
Radiographs
Being
universally available, inexpensive and
easily accessible, plain x-rays are
naturally the first (and often the only)
examination required in screening for
spinal injuries. A single lateral view,
three-view series, five-view series and
dynamic flexion-extension views have all
been described for cervical spine
clearance with various degrees of
sensitivity and
specificity.(28,29,30,31,32)
Though
easily obtainable, the single cross-table
lateral view of the cervical spine has
been blamed for missing a significant
portion of spinal injuries.(28,29) The
three-view series is reported to be more
sensitive than the single lateral
view.(30) The addition of trauma oblique views,
i.e. five-view series, was not found to
add to the accuracy of the three-view
series. Missing a cervical spine injury in
a patient with normal three-view and
flexion-extension x-rays is believed to be
very unlikely.(31,32)
The
three-view trauma series comprises
anteroposterior, lateral and open-mouth
views. The anteroposterior films should
show the spinous processes of C2 to T1,
while the open-mouth film should show the
lateral masses of C1, together with the
entire odontoid peg. (Fig.1)
Figure 1 : An open mouth view showing the odontoid
peg
and atlantoaxial joints
The lateral
view must show the full length of the
cervical spine from the occiput (C0)
through C7-T1 junction, otherwise the test
is considered incomplete. Acceptance of
the latter is a potential trap for missing
fractures. If difficulty is experienced in
viewing the lower end of the cervical
spine, i.e. the cervicothoracic junction,
the x-ray should be repeated while
applying gentle caudal traction to the
arms. Failing this, a Swimmer's
View should be taken. (Fig.2)
Figure 2 : An incomplete
lateral cervical spine radiograph that
missed
a C6-C7 subluxation which was revealed in
the Swimmer's view
We request
trauma oblique views infrequently when
attempts at showing the cervicothoracic
junction by traction and on Swimmer's
View fail in a patient who would not be
ready in time to undergo a CT scan.
If any
abnormality appears in the cervical spine
following the above tests, the thoracic
and lumbar spines must be fully
examined.(18,19,21)
The main
goal of this test is to detect instability
due to ligamentous injuries in a
symptomatic, coherent patient with normal
appearance of his initial x-rays. The
presence of neurological symptoms or signs
mandates an MRI study prior to considering
flexion-extension views.
Under
supervision, the patient is asked to
actively flex and extend his neck to the
maximum limit possible. The appearance of
any abnormality would demand CT
examination, as outlined below. If the
test turns normal while the patient
remains symptomatic, follow up examination
is suggested in a couple of week's
time when muscle spasm is expected to have
settled.
The issue
of clearing the cervical spine in the
unconscious patient by performing passive
flexion-extension examination under
fluoroscopic guidance has raised
controversy.(33, 34, 35, 36) The
advocates believe it helps take an
early decision to discontinue unnecessary
restraints in the severely injured patient
undergoing treatment in the intensive care
unit. The opponents, on the other hand,
feel that the risks associated with
passive movement of the cervical spinal in
the unconscious outweigh the benefits
gained by early clearance. It appears that
such cases ought to be assessed
individually and the decision to
discontinue (or continue) cervical
immobilization has to be based on each
patient’s own merits.
Role
of CT Scan in cervical spine trauma
High resolution
computed tomography scanning is superior
to plain radiography in showing spinal
fractures and spinal canal dimensions.
The
capability of obtaining sagittal and
coronal reconstructions of the axial cuts
and the formation of three-dimensional
views give more insight into understanding
the mechanism of the injury and, hence,
help better management planning.(37) (Fig
3)
Figure 3 : (a) Axial CT scan showing bilateral facet
dislocation and
(b) Sagittal reconstruction demonstrating
the resultant subluxation
Routine CT scanning
of the entire cervical spine of the
acutely injured has been practiced in some
trauma centres.(38)
This does not appear
to have made a significant addition to the
diagnostic sensitivity acquired by plain
radiography and supplementary CT study.
Indeed, a selective CT scan examination
targeting regions that are difficult to
view on plain x-rays and/or areas noted to
be suspicious on plain radiography has
been reported to improve the sensitivity
substantially.(14, 39, 40, 41)
In our unit, we
routinely obtain a CT scan of the occiput
(C0) through C2 at the time of performing
head CT scans in the unconscious trauma
patients. The cervicothoracic junction is
also included in the examination, if prior
attempts with plain radiography failed to
show this.
The other indication
for CT scanning of the cervical spine is
to examine fracture sites or areas felt to
be suspicious on plain x-rays. Here, the
scan should extend to include adjacent
intact segments above and below that
level. This provides important information
for the surgeon should surgical fixation
be considered in due course.
The following is a
summary of the process of CT scanning in
cervical trauma:
1.
C0-C2 scan at the
time of head CT scanning for severe head
trauma.
2. C7-T1 scan in
failed plain x-ray imaging.
3. Scan indicated if
a fracture is confirmed or suspected on
x-rays.
4. Include entire
intact vertebral body above and below the
fracture level.
5. Perform 1-3mm
(usually 2mm) thin axial slices or,
preferably, a volume spiral scan.
6. Acquire filming on
wide bony window (W=1500, C=300).
7. Obtain sagittal
reconstruction to cover the width
extending from one facet joint to the
other.
8. 3-D reconstruction
views may be helpful.
Role of MRI in cervical spine trauma The role of the MRI
in screening for cervical spine injuries
has not yet been standardised.(17)
The
sensitivity of MRI scans in depicting soft
tissue abnormalities following trauma
could be helpful in identifying
ligamentous injuries.(42) Traumatic
intervertebral disc herniation is readily
seen on MRI scans, which also reveal
spinal cord contusions and traumatic
haematomas. (Fig. 4)
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Figure
4: (a) lateral spine x-ray
showing C4-C5 disassociation in a 4-year old
pedestrian child who was hit by a
fast-running vehicle. (b)
MRI (sagittal T2 W1) showing evidence of
spinal cord contusion as bright signal
changes within the cord. There are
also signs of soft tissue injuries shown as
signal changes in the prevertebral space and
within the posteriorl igament complex
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Subtle bony injuries
that might not be seen on either plain
x-rays or CT scans could be visualized as
changes in the signal of the vertebral
body marrow.(43) Moreover, MRI has the
added advantage of offering information
for prognostication and outcome prediction
after spinal cord injury.(44,45)
On the other hand,
MRI may give alarming false positive
results in patients who otherwise would
have normal plain films, flexion-extension
views and CT scans(46).
The consensus,
however, is that MRI is indicated in
patients with neurological manifestations
due to cervical spine cord or nerve roots
injuries. The investigation has largely
replaced the more invasive test of
myelography, though myelography combined
with CT might still be used in special
circumstances when MRI is not available or
is contraindicated (for example due to the
presence of a ferromagnetic metallic
implant).
In our practice, the
MRI timing in the sequential order of the
management plan is crucial. We perform MRI
early before commencing skull traction if
this is indicated prior to surgical
intervention. MRI is performed, with
continual cervical immobilization, after
completion of the plain x-ray examinations
and CT assessment. If skull traction is
indicated, the patient is then placed on a
Stryker Wedge Turning Frame (Stryker
Corporation, Kalamazoo, Michigan, USA).
After reduction is achieved, traction is
maintained while the patient is taken to
the operation theatre on the same frame
that replaces the operating table.
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