CT morphometric analysis of the cervical spinal canal with special reference to the correlation with the vertebral level

Narrowness of the spinal canal is associated with the development of cervical myelopathy. While studies have addressed the sagittal diameter of the cervical spinal canal, few evaluated the correlation between the size of the spinal canal and the vertebral level. We addressed this issue. Our retrospective study included 102 patients with cranial or spinal disorders. We examined the correlation between the cervical spinal canal diameter (SCD) at C1 to C7 and the inner anteroposterior diameter (IAPD) of the atlas on CT images. At C1, the SCD was largest, at C4 it was smallest. While there was a strong correlation between the IAPD and the SCD at C1 (r = 0.8), the correlation between the size of the atlas and the SCD at C4 to C7 was weak (r = 0.2–0.3). We divided our patients into a normal group (n = 34, SCD ≥ 12 mm at any levels) and a stenosis group (n = 68, SCD