Jared Christensen,
MD, and P-L Westesson, MD, PhD, DDS
Clinical
Presentation:
A
15-year-old male post-motor vehicle collision with neck pain and right arm paraesthesia.
Imaging Findings: CT: Decreased C7 vertebral body height with retropulsion of fracture fragments involving approximately 50% of the canal. MR: C7 vertebral body fracture again identified with fracture fragments narrowing the thecal sac and deforming the right ventral aspect of the spinal cord. There is however no signal abnormality within the cord. Sagittal sequences demonstrate thickening of the posterior longitudinal ligament with a focal collection within the epidural space that is high on T2- and isointense on T1-weighted images.
Figure 1: Sagittal and axial images from a noncontrast multidetector acquisition CT study of the cervical spine. A. Midline sagittal view demonstrates an oblique fracture extending through the superior and inferior C7 vertebral body endplates. There is associated retropulsion of fracture fragments along the superior aspect, narrowing the central canal (arrow). B. Axial image through C7 shows fracture fragment retropulsion compromising approximately 50% of the central canal.
Figure 2: T2-weighted sequences of the cervical spine. A. Select sagittal image corresponds with similar CT findings -- C7 burst fracture with fragment retropulsion (arrowhead) compromising the central canal. A focus of high signal along the posterior aspect of the C7 vertebral body is consistent with acute hemorrhage (arrow). B. Axial image through C7 demonstrates deformation of the spinal cord by the retropulsed fragments. Hover over the image to highlight the cord.
Figure 3: Volume reconstructions with surface rendering of the skull base and cervical spine highlight the normal lumen of the vertebral foramen at the level of C6 (A) versus the markedly narrowed foramen at C7 (B).
Diagnosis: C7 burst fracture with cord compression and associated small epidural hematoma
Discussion: Burst fractures are classically due to vertical compression associated with axial loading with our without a component of flexion. They involve the anterior and middle spinal columns, but spare the posterior column (pedicles, facets, spinous processes and all associated ligaments). The injury most commonly occurs with the neck in neutral position or mild flexion resulting in a circumferential distribution of force. The anterior aspect of the vertebral body is relatively protected by stabilizing ligaments and musculature; however the posterior aspect of the vertebral body — the middle column — is open to the spinal canal. With a sufficient axial load, the adjacent disk herniates into the vertebral body and preferentially disseminates the force laterally and posteriorly. The posterior elements and soft tissues are not involved given that the axial load is directed into the central canal. The mid and lower cervical spine are most commonly affected.
Imaging features include the following:
Radiographs and CT:
Diminished vertebral body height
Fracture line extending through both the superior and inferior end plates with or without focal flexion (gibbus) deformity
Widening of the interpedicular distance on AP radiographs and coronal CT reformats
CT should be performed if fracture of the cervical vertebral body is identified on radiographs or if radiograph evaluation is limited. CT is essential for fracture characterization and assessing extent of central canal narrowing.
MRI:
Similar findings as above, but with increased marrow T2 signal of the involved vertebral body
Useful for the evaluation of associated epidural and soft tissue hemorrhage
Essential for evaluation of the spinal cord in patients with neurologic symptoms
CTA or MRA should be obtained if the fracture is found to involve the vertebral artery foramen to exclude vascular injury
In addition to burst fracture, differential considerations of a compressed vertebral body include benign compression fracture (no end-plate to end-plate comminution and no fragment retropulsion), pathologic compression fracture (focal lesion within the vertebral body), and flexion compression fracture (involves posterior elements). All burst fractures have the potential to be neurologically devastating and are considered unstable. Surgical intervention for decompression and stabilization is indicated in the neurologically compromised patient. This typically consists of anterior vertebrectomy, reconstruction, and cervical plating. Management of burst fractures in patients without neurologic symptoms is controversial.
References:
Katzberg RW, Benedetti PF, Drake CM, et al. Acute cervical spine injuries: prospective MR imaging assessment at a level 1 trauma center. Radiology. 1999 Oct;213(1):203-12. [Medline]
Ross JS, et al. Diagnostic Imaging: Spine, Amirsys, 2004, 1:42-43.
