Assessment of craniocervical junction and atlantoaxial relation using metrizamide-enhanced CT in flexion and extension.

Metrizamide-enhanced computed tomographic (CT) myelography has made it easier to define the relation of the spinal cord to the vertebral canal. A flexion-extension metrizamide-enhanced CT technique has been developed to study the craniocervical junction that refines evaluation of the relation between the spinal cord and the foramen magnum, atlas, and axis. This technique was used to study 15 adults who had had a structurally normal examination of the upper cervical cord and foramen magnum. The average movement of the upper cervical cord was shown to be 1 mm. The advantages of the flexion-extension metrizamide-enhanced CT examination were evident in 10 other patients who had a variety of craniocervical junction pathologies.