Hyperextension dislocation of the cervical spine.

The purpose of this report is to describe hyperextension dislocation of the cervical spine and to illustrate its often subtle radiographic features. An analysis of the lateral cervical spine radiographs in 20 patients with hyperextension dislocation of the cervical spine revealed the combination of diffuse prevertebral soft-tissue widening together with normally aligned cervical vertebrae in all patients with this injury. In six (30%) of 20 patients, this combination of findings was the only radiographic sign. The precise level of dislocation was indicated by a thin, transversely oriented avulsion fracture fragment arising from the anterior aspect of the inferior end-plate of the dislocated vertebra in 13 (65%) of 20 patients, by a vacuum defect in the intervertebral disk subjacent to the dislocated vertebra in three (15%), by a widened intervertebral disk space in three (15%), and by comminuted fracture of the spinous process in one (5%). Clinically, all 20 patients had facial trauma and all had some manifestation of the acute central cervical spinal cord syndrome.