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I. Imaging of the Spine in Victims of Trauma
II. Authors
C. Craig Blackmore, MD, MPH
Department of Radiology
Gregory Avey, MD
Department of Radiology
Harborview Medical Center
University of Washington
325 Ninth Avenue, Box 359728
Seattle WA 98104
206-731-3561
fax: 206-731-8560
KEY POINTS
ISSUES:
1.
The cervical spine:
A. Who should undergo cervical spine imaging?
B. What imaging is appropriate in high-risk subjects?
Special case: Defining subjects at high fracture risk
Special case: The unconscious patient
2.
The thoracolumbar spine:
A. Who should undergo thoracolumbar spine imaging?
B. What imaging is appropriate in blunt trauma patients?
IV KEY POINTS:
- Cervical spine imaging is not necessary in subjects with all five of the following: 1.
absence of posterior midline tenderness, 2. absence of focal neurological deficit, 3.
normal level of alertness, 4. no evidence of intoxication, and 5.absence of painful
distracting injury. (STRONG EVIDENCE)
- CT scan of the cervical spine is cost-effective as the initial imaging strategy in subjects
at high probability of fracture (neurological deficit, head injury, high energy mechanism)
who are already to undergo head CT. (MODERATE EVIDENCE)
- No adequate data exists on the appropriate cervical spine evaluation in subjects who are
unexaminable due to head injury. (INSUFFICIENT EVIDENCE)
- Imaging of the thoracolumbar spine is not necessary in blunt trauma patients with all
five of the following: 1. absence of thoracolumbar back pain, 2. absence of
thoracolumbar spine tenderness on midline palpation, 3. normal level of alertness, 4.
absence of distracting injury, 5. no evidence of intoxication. (MODERATE EVIDENCE)
1. Cervical Spine
Issue A: Who should undergo cervical spine imaging?
Summary
Determination of which blunt trauma subjects should undergo cervical spine imaging,
and which should not undergo imaging, is a question that has been studied in detail in
literally tens of thousands of subjects. The two major Level 2 (Moderate Evidence)
studies, the NEXUS trial and the Canadian C-spine Rule, were comprehensive
multicenter investigations of this topic. The NEXUS rule has undergone extensive
validation and demonstrates high sensitivity for detection of fractures. The Canadian Cspine rule also has high sensitivity, and potentially higher specificity than the NEXUS.
However, neither of these rules has been tested in an implementation trial to determine
their impact outside the research setting.
Issue B: What cervical spine imaging is appropriate in high-risk subjects?
Summary
Cervical spine CT is more sensitive than radiography, and more specific in subjects at
high risk of fracture. CT has higher direct costs than radiography. However, costeffectiveness analysis demonstrates that CT is cost-effective, and may actually be cost-
saving from the societal perspective in subjects at high probability of fracture. Cost
savings with CT are from a decreased number of second imaging examinations resulting
from inadequate radiograph studies, and to the high cost in dollars and health for the rare
fracture missed from radiography that leads to severe neurological deficit. Radiography
remains the most cost-effective imaging option in subjects at low probability of injury.
Special Case: Defining subjects at high fracture risk
Summary
Selection of subjects for cost-effective use of cervical spine CT is dependent on
probability of fracture. The Harborview high-risk cervical spine criteria have been
developed and validated by a single institution Level 2 (Moderate Evidence) study.
Using these criteria, subjects can be identified with injury probabilities ranging from
0.2% to 12.8%.
Special Case: The unconscious patient
Summary
The theoretical risk of radiographically occult unstable ligamentous injury in subjects
who are unexaminable due to head injury has lead to a variety of imaging approaches.
There is insufficient evidence to support any particular approach.
2. The Thoracolumbar Spine
Issue A: Who should undergo thoracolumbar imaging?
Summary
Clinical prediction rules to determine which patients should undergo thoracolumbar spine
imaging have been developed, but not validated. Although these prediction rules have
high sensitivities for detecting thoracolumbar fractures, their low specificities and low
positive predictive values would require imaging a large number of patients without
thoracolumbar injuries. This drawback limits the clinical utility of these prediction rules
[Moderate evidence].
B. What thoracolumbar imaging is appropriate in blunt trauma patients?
Summary
Multiple studies have shown that some CT protocols used for imaging the chest and
abdominal visceral organs are more sensitive and specific for detecting thoracolumbar
spine fracture than conventional radiography. In patients undergoing such scans,
conventional radiography may be eliminated [Limited evidence]. The effect of primary
screening with CT scan on cost and radiation exposure has not been thoroughly studied
for the thoracolumbar spine.
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