Cervical spine hyperextension injuries: MR findings.

Cervical hyperextension injuries are common and often show minimal radiographic abnormalities, even with severe or unstable lesions. Fourteen patients, nine with acceleration hyperextension "whiplash" injuries and five injured by direct frontal head trauma, underwent magnetic resonance (MR) imaging within 4 months of injury. Five of seven patients with anterior spinal column injuries showed characteristic separation of the disk from the vertebral end plate, lesions still evident as late as 9 months after injury. The demonstration of this type of lesion and its delayed resolution may have prognostic and surgical implications. These lesions, anterior longitudinal ligament injuries, anterior annular tears, and occult anterior vertebral end-plate fractures usually occurred at multiple levels except when preexistent degenerative disk narrowing reduced spine mobility. Seven patients had acute cervical disk herniations causing cord impingement. Radiographically occult injuries are well demonstrated with MR imaging, and findings correspond to previously described surgical and anatomical pathologic conditions.