CT anatomy of the craniovertebral junction in infants and children.

Computed tomographic (GE 9800) images of 129 patients (from newborn to 18 years old) with no evidence of cervical spine pathology were reviewed retrospectively from available material to evaluate normal anatomic appearances in childhood. The synchondroses may appear solid at soft-tissue window settings, while, with appropriate bone-window settings, a lucent line will be seen. Residual lucency and then (generally) sclerosis were seen at synchondroses past the age of classic anatomic fusion. A transversely oriented groove on the undersurfaces of the occipital condyles was imaged in children ages 5-12 years. This groove is described radiologically in that age range for the first time in this report. The development of the ossification centers of C1 was illustrated with CT. The two vertically oriented, rod-shaped ossification centers of the lower dens develop a bilobed appearance in axial section when they begin to fuse. An apparent deficiency of the cortex seen posteriorly in this area (in children as old as 7 years) represents the last remnant of the cleft between the dens centers. The cord was always outlined distinctly by CSF at soft-tissue settings at the foramen magnum and C1 levels without intrathecal or IV contrast enhancement. This anatomic feature is particularly useful since it enables the evaluation of the spinal canal in this region in some cases (especially craniovertebral junction anomalies) without the need for intrathecal contrast materials.