Hyper-extension injury of the neck with ALL disruption
Front-seat passenger in a car involved in a high speed MVA (car vs tree) sustaining multiple facial lacerations and facial edema. Complaining of mild cervical pain following the accident.
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Congenital fusion of C5 and C6, with scoliosis and anterior widening of the C6/7 intervertebral disc space. Increase in signal intensity of the C6/C7 disc and complete disruption of the anterior longitudinal ligament. There is a mild disc bulge with anterior indentation of the cord and narrow canal. There is no cord compression. Posterior longitudinal ligament intact. High T2 signal intensity in the prevertebral space extending from C2 to C5 consistent with oedema /haematoma.
This case illustrates C6/7 anterior longitudinal ligament disruption with widening of the disc space anteriorly and a prevertebral space oedema/haematoma extending from C2 to C5. These traumatic changes are most consistent with a hyperextension injury of the cervical spine.
A severe hyperextension force to the face and neck can result in momentary posterior dislocation of the involved cervical vertebrae, producing injury to the cervical spinal cord and supporting soft-tissue structures. Forceful cervical hyperextension causes tension and results in disruption of the anterior longitudinal ligament (which may tear at the intervertebral disc space or at the margin of the vertebral body; the latter results in an avulsion fracture of the anterior superior or inferior margin of the vertebral body), the annulus fibrosis of the intervertebral disc, and the ligamentum flavum. In severe cases, there is associated stripping of the posterior longitudinal ligament and tearing of associated paraspinal musculature.
Furthermore, in patients, such as this one, with congenital fusion, the remaining free articulations of the cervical spine are more susceptible to acute trauma. This is due to the relative inflexibility of the cervical spine. These patients are particularly prone to hyperextension trauma.
Radiographic evaluation of hyperextension injuries on plain radiographs and/or CT may demonstrate:
- Misalignment of vertebrae (hyperextension dislocation)
- Presence of diffuse prevertebral soft-tissue swelling
- Widening of the disk space anteriorly
- Avulsion fracture, where the transverse dimension of the anteroinferior avulsion fracture fragment is characteristically greater than its vertical dimension (differentiating this from a hyperextension teardrop fracture, where the triangular fragment has a greater vertical than transverse dimension)
MR imaging is ideal for visualizing any associated soft-tissue injury and/or spinal cord pathology. The presence of ligamentous and disc disruption, along with hemorrhage and edema in the prevertebral space, are optimally demonstrated on sagittal views. High-signal-intensity edema and susceptibility artifact from hemorrhage within the spinal cord may accompany these findings.
Case courtesy of Associated Professor Pramit Phal