[Morphological changes of the cervical spinal canal and cord due to aging]

Cervical spondylotic myelopathy is a condition in which degenerative changes of the cervical vertebral bodies and the intervertebral discs cause disturbances to the spinal cord either by direct mechanical compression or by disturbing the blood supply. There have been a number of studies on roentgenological measurements of the anteroposterior (AP) diameter of the cervical spinal canal relating to the disorder. However, there are only a few reports concerning the shape and the size of the spinal canal and the spinal cord. Murone reported that the cervical spinal canal of Japanese was significantly smaller than those of Europeans on roentgenograms. However, whether the size of the spinal cord of Japanese is proportionally smaller or not remains to be studied. The aim of the present study is to perform various measurements of the human cervical spine specimens to find any influence of the age on them and to see relative correlation of the spinal cord size to the corresponding spinal canal size.

Seventy-seven human cervical spinal columns taken én bloc from C3 to C7 at post-mortem examination were used for the study. After taking AP and lateral roentgenograms, the specimen was horizontally transsected at the middle of each vertebral body and at the level of each intervertebral disc. The reason why the middle of the vertebral body was selected is to exclude modifications by osteophyte formation at the upper and the lower ends of the body and to see possible genuine appearance and change of the spinal canal. The measured items were AP diameter of the vertebral body (A), AP diameter of the spinal canal (B), area of the spinal canal (C), AP diameter of the spinal cord (beta) and area of the spinal cord (gamma). In five untreated specimens, CT-scan was performed prior to the horizontal section, and the CT-scan findings were compared to those by direct measurements. Lateral cervical roentgenograms of 249 patients of various ages were used as a comparison.

The AP diameter of the vertebral body (A) and the AP diameter of the spinal canal (B) showed some correlation with the age. The former became larger whereas the latter became smaller with the age. The area of the spinal canal (C) did not show correlation with the age. The AP diameter of the spinal cord (beta) showed correlation with the age, whereas the area of the spinal cord (gamma) failed to show the correlation.(ABSTRACT TRUNCATED AT 400 WORDS)