Image Quiz
Pain and Tenderness in the Neck After a Motorcycle Accident (continued)
Answer: Posterior atlantoaxial dislocation with intact odontoid process.
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Fig. 1 Axial computed tomography scan showing a posterior atlantoaxial dislocation. The arch of the atlas is posterior to the intact odontoid.
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The patient was taken emergently to the operating room and, after fiberoptic intubation, underwent a manual closed reduction of the atlantoaxial dislocation. Spinal cord monitoring was not available. The reduction maneuver, performed with use of a halo ring, involved distraction, hyperextension, and slight lateral bending of the neck under fluoroscopic control. When the patient was awakened from the anesthesia he was neurologically intact. Controlled active flexion and extension of the cervical spine under fluoroscopic control in the operating room showed no instability. A computed tomography scan performed two hours after the reduction demonstrated anatomic reduction ( Fig. 2 ).
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Fig. 2 After reduction, the axial computed tomography scan of the cervical spine demonstrated an anatomic reduction of the atlantoaxial joint.
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Discussion
Most atlantoaxial dislocations are associated with odontoid fracture or rupture of the transverse atlantal ligament. Nearly all reported dislocations have been anterior, with only five published cases of posterior dislocation, to our knowledge. Posterior atlantoaxial dislocation without a fracture of the odontoid process is a rare injury, with only five cases identified in our review of the literature. Since the majority of such injuries may be fatal, it is not possible to determine their true prevalence. The best treatment of these rare injuries is unknown. Possible techniques for reduction include closed manipulation, skull traction, and open decompression and reduction. Because of the neurologic risks of traction and manipulation, closed reduction under general anesthesia should be performed with use of awake intubation, fluoroscopic control, and, if possible, spinal cord monitoring. Most authors of previous studies have favored closed reduction.
Reference
1. Neumann U, Urbanski H, Riedel K. Posterior atlantoaxial dislocation without fracture of the odontoid: a case report. J Bone Joint Surg Am. 2003;85:1343-6.
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