Dynamic studies of cervical spinal canal and spinal cord by magnetic resonance imaging.

In 15 cases dynamic studies of cervical spinal cord and canal in flexion and extension were performed by magnetic resonance imaging (MRI). In addition measurements of the complete spinal cord were made in 5 cases. As compared with extension the cervical spinal canal and spinal cord lengthen 12 mm in average during flexion, whereas the spinal canal lengthens 28 mm in average, which means a difference of about 15 mm. We feel that these results indicate that adverse mechanical tension may occur in the cervical spinal cord during flexion. The impact of these results on surgical treatment for chronic cervical myelopathy is discussed.