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The standard radiological examination of the cervical
spine in the unconscious, intubated patient is :
- Lateral cervical spine film
- Antero-posterior cervical spine film
- CT scan of occiput - C3
The open-mouth odontoid radiograph is inadequate in
intubated patients and will miss up to 17% of injuries
to the upper cervical spine.
Thin-cut (2mm) axial CT scanning on specific bone windows,
with sagittal and coronal reconstruction should be used
to evaluate abnormal, suspicious or poorly visualised
areas on plain radiology. With technically adequate
studies and experienced interpretation, the combination
of plain radiology and directed CT scanning provides
a false negative rate of less than 0.1%. The scan should
include the entire vertebral body above and below the
region of interest, as these must be undamaged for subsequent
internal fixation.
Ligamentous Instability
Clearance of the spine in unconscious patients is limited
by the lack of clinical information. The incidence of
unstable spinal injury in adult, intubated trauma patients
is around 10.2%. The incidence of unstable, occult spinal
trauma (not visible on plain films is around 2.5%. The
options for full clearance of cervical spine injury
are:
- Continue precautions until fully conscious
- Magnetic Resonance Imaging
- Dynamic Flexion-Extension Fluoroscopy
- CT Scan whole cervical spine
Continue spinal precautions until
fully conscious.
Where the patient is expected to regain full consciousness
in the following 24-48 hours, patients can be nursed
with full spinal precuations. Once the patient has returned
to full consciousness, clinical examination can exclude
significant ligamentous injury.
Prolonged spinal immobilisation in critically ill patients
leads to decubitus ulcers and deep venous thromboses
while compromising nursing care, respiratory support
and the management of traumatic brain injury.
A semi-rigid collar is not necessary in the adequately
sedated, ventilated patient, and may increase intracranial
pressure in patients with traumatic brain injury.
Magnetic Resonance Imaging
MRI is extremely sensitive at detecting soft tissue
injuries without stressing the cervical spine. However
the significance of such injuries with regards to the
clinical stability of the spine is not clear, and the
number of false positive examinations is high. MRI of
ventilated patients is a significant undertaking requiring
special non-ferromagnetic equipment. However the increasing
use of MRI for critically ill patients is making this
equipment cheaper and more widely available. Possibly
because of the difficulties associated with undertaking
routine MRI scans in these patients, there have been
few good studies on the use of MRI in clearing the cervical
spine in unconscious patients.
Dynamic Flexion-Extension Fluoroscopy
Fluoroscopy Passive dynamic flexion/extension stressing
of the cervical spine, performed by an experienced clinician,
should reveal most significant ligamentous injuries.
Several centres have reported their results, and some
guidelines give primary support to the use of dynamic
fluoroscopy in clearance of the spine in unconscious
patients.
However, there are significant difficulties in performing
flexion/extension imaging routinely on the intensive
care unit, and many spinal surgeons are unwilling to
perform the study due to safety & resource implications.
Of 625 patients currently reported in the literature,
dynamic fluoroscopy has a sensitivity of 92.3% and specificity
of 98.8%. Two cases of neurological deterioration during
the study have been reported, including one complete
quadriplegia.
CT Scan whole Cervical Spine
In recent years, the concept of full cervical spine
CT for assessment of spinal injury has emerged. There
are several studies that have demonstrated the robustness
of the full CT scan, with sagittal and coronal reconstructions,
for the exclusion of significant spinal injury. Widening,
slippage or rotational abnormalities of the cervical
vertebrae suggest soft tissue injury. An absence of
such signs appears to exclude significant instability.
Abnormal findings on the CT scan are evaluated by a
spinal surgeon and additional modalities, such as MRI,
can be employed. No study has missed a cervical spine
injury, and no study has identified an injury on plain
films that was not apparent on the CT scan.
Helical or multislice CT scanning from the Occiput
to T1 is performed at 2-3mm collimation and 1.5mm pitch.
Sagittal and coronal reconstructions are must be closely
examined for indications of ligamentous instability.
When whole cervical spine CT scanning is performed,
the antero-posterior plain film becomes redundant.
References
Computed Tomography of Occiput - C3
Kirshenbaum KJ, Nadimpalli SR, Fantus R, et al: Unsuspected
upper cervical spine fractures associated with significant
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Schenarts PJ, Diaz J, Kaiser C et al 'Prospective
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Incidence of Ligamentous Instability
Chiu WC, Haan JM, Cushing BM, Kramer ME, Scalea TM.
Ligamentous injuries of the cervical spine in unreliable
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J Trauma 2001 Mar;50(3):457-63;
Demetriades D, Charalambides K, Chahwan S et al 'Nonskeletal
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Dynamic Fluoroscopy
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Hino H, Abumi K, Kanayama M, Kaneda K Dynamic motion
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Sees DW, Rodriguez Cruz LR, Flaherty SF. The use
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Computed Tomography of Complete Cervical Spine
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spine clearance protocol using computed tomography.'
J Trauma. 2001 Oct;51(4):652-6
Berne JD, Velmahos GC, El-Tawil Q et al 'Value of
complete cervical helical computed tomographic scanning
in identifying cervical spine injury in the unevaluable
blunt trauma patient with multiple injuries: a prospective
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Daffner RH. 'Helical CT of the cervical spine for
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