Computed tomographic artifact suggesting cervical facet subluxation.

STUDY DESIGN: A case report with review of the literature on the cause of computed tomographic (CT) artifacts and recommendations for identification of such artifacts. OBJECTIVE: To describe the presentation of a patient with a CT scan suggesting a cervical facet dislocation that ultimately proved to be artifactual. SUMMARY OF BACKGROUND DATA: CT scanning is routinely used in the detection of cervical spine injuries. This technique has a reported sensitivity of 98%, although specificity has proved more difficult to estimate. CT artifacts such as the case reported here is a significant cause of a decrease in specificity for this technique. METHODS: A 30-year-old woman with a history of a cervical fracture developed severe neck pain without neurologic deficit after trauma to the back of her neck. CT scans were obtained and reviewed at a local secondary level hospital. A cervical fracture dislocation was diagnosed and cervical spinal injury protocols were initiated and the patient transferred to authors', tertiary level institution for surgical management. A repeat CT scan showed her cervical spine to be in normal alignment. RESULTS: A movement artifact in the patient's original CT scans was misinterpreted as a unilateral facet fracture subluxation at C5-C6. There are two clues that in hindsight indicate that this finding was artifactual; an ill-defined tracheal margin in contrast with the sharply defined margin above and below the level of the artifact and a double bone margin seen on axial sections at the level of the artifact. CONCLUSION: Motion artifacts are an important cause in the reduction in specificity of CT scans and can be easily missed. It is important to be aware of the indicators of motion artifacts to reduce the risk of unnecessary treatments.