AJR 2000; 175:540
© American Roentgen Ray Society
Trauma Cases from Harborview Medical Center |
Rotatory Subluxation and Fracture at C1—C2
Stanley G. Cheng1,
C. Craig Blackmore1,
Sohail K. Mirza2 and
John H. Harris, Jr.3
1
Department of Radiology, Harborview Medical Center, University of Washington
School of Medicine, 325 Ninth Ave., Seattle, WA 98104.
2
Department of Orthopedic Surgery, Harborview Medical Center, University of
Washington School of Medicine, Seattle, WA 98104.
3
Department of Radiology, University of Texas—Houston Medical Center, The
University of Texas—Houston Medical School, 6431 Fannin St., MSB 2.100,
Houston, TX 77030.
Received March 14, 2000;
accepted after revision March 24, 2000.
This is another in the continuing series on radiology in trauma cases from
Harborview Medical Center. Editors: Fred A. Mann, Eric J. Stern, and Alexander
B. Baxter.
C. Blackmore received salary support as a General
Electric—Association of University Radiologists academic research
fellow.
Address correspondence to F.A. Mann.
Introduction
A 43-year-old man fell 25 ft (7.62 m) onto his back, suffering loss of
consciousness but no focal neurologic deficits. On the initial cross-table
lateral radiograph, the visualized cervical vertebrae were normally aligned.
The head was markedly tilted, and neither the dens nor C1 was visible. The
cervical cranial prevertebral soft-tissue contour showed abnormal anterior
convexity (Fig. 1A). Screening
cervical spine CT showed a displaced C1—C2 dislocation fracture with a
type 11 odontoid fracture, an incomplete sagittal fracture of the C2 body, and
a comminuted fracture of the right articular mass of C2 (Figs.
1B,1C,1D).
The patient underwent closed reduction and subsequent C1—C2 posterior
fusion with transarticular screw fixation.
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Fig. 1A. —43-year-old man who sustained C1—C2 fracture dislocation after
falling 25 ft (7.62 m). Cross-table lateral cervical spine radiograph
performed in resuscitation area shows abnormal soft-tissue contour
(arrow) anterior to dens and body of C2. Patient's head is tilted,
and dens and C1 ring are not completely seen.
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Fig. 1B. —43-year-old man who sustained C1—C2 fracture dislocation after
falling 25 ft (7.62 m). Reformatted sagittal CT scan reveals fracture
(straight arrow) at base of dens. Note abnormal alignment between
anterior axis and dens. Abnormal soft-tissue contour (curved arrow)
is again seen.
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Fig. 1C. —43-year-old man who sustained C1—C2 fracture dislocation after
falling 25 ft (7.62 m). Extent of right lateral displacement of dens
(curved arrow) is shown on reformatted coronal CT scan, as is
subluxation of C1 lateral masses with respect to articular facets of C2
(open arrow).
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Fig. 1D. —43-year-old man who sustained C1—C2 fracture dislocation after
falling 25 ft (7.62 m). Complex rotation and tilt of C1 with respect to C2 is
clarified with three-dimensional rendering of CT scans. View is posterior with
C1 and C2 laminae labeled.
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Evaluating the soft tissues of the prevertebral space is an integral part
of examining the lateral cervical spine radiograph
[1]. The radiographic
prevertebral space projects between the vertebral column and the air shadows
of the pharynx or trachea. Soft-tissue swelling results from hemorrhage and
edema caused by disruption of blood vessels covering the anterior cervical
spine in hyperextension injuries and by the fracture itself in anterior
vertebral body and odontoid fractures. Widening is often maximal on early
radiographs in 0-3 days, and returns to normal in 1-3 weeks
[2].
A wide range of normal values has been established for the prevertebral
tissue width, which limits the diagnostic value of this width. In adults,
injury is unlikely with less than 5 mm of soft tissue anterior to C3; injury
is possible with 5-7 mm; and injury is likely with more than 10 mm
[3]. More useful, however, may
be the contour of the soft-tissue outline, particularly at the cervicocranial
junction. The prevertebral soft tissues normally follow the contour of the
anterior cervical spine, and focal convexities are suggestive of injury.
Indistinctness or irregularity of the usually sharp air—soft-tissue
interface also suggests injury
[1]. Assessment of the
prevertebral soft tissues is not valid when an endotracheal tube or
nasogastric tube is present
[4].
Prevertebral soft-tissue swelling may be the only radiographic sign of
underlying injury, and its presence should prompt a meticulous examination,
potentially including CT or MR imaging. In the case presented, the focal
softtissue swelling anterior to the cervicocranial junction indicates injury,
which was defined by CT. Other injuries, especially Le Fort's fractures, may
also produce prevertebral soft-tissue swelling. In the absence of injury,
tumor and infection need to be considered
[3].
References
-
Harris JH, Mirvis SE. The radiography of acute cervical
spine trauma, 3rd ed. Baltimore: Williams & Wilkins,
1996: 36-42
-
Penning L. Prevertebral hematoma in cervical spine injury.
AJR
1981;136:553
-561[Abstract/Free Full Text]
-
Rogers LF. Radiology of skeletal trauma,
2nd ed. New York: Churchill Livingstone, 1992:451
-521
-
Harris JH. Abnormal cervicocranial retropharyngeal soft-tissue
contour in the detection of subtle acute cervicocranial injuries.
Emerg Radiol 1994;1
: 15-21
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Introduction
References
