Normal morphology of the cervical spinal cord and spinal canal using MRI in Japanese

The purpose of this study was to establish standard MRI values for the cervical spinal canal, dural tube, and spinal cord in healthy Japanese subjects and to define developmental stenosis of the cervical spinal canal based on MRI data. To establish standard values for ''finger grip and release in 10 seconds (G and R test)'' and ''10 second step test'' in healthy Japanese subjects. There were approximately 100 volunteers representing each gender and generation, including persons aged in their 20s to 70s. The sagittal diameter of the spinal canal, and the sagittal diameter and axial area of the dural tube and spinal cord were measured on MRIs of 1,211 subjects. From this data, we calculated the spinal cord occupation rate in the dural tube for defining developmental stenosis of the cervical spinal canal. ''Finger grip and release in 10 seconds (G and R test)'' and ''10 second step test'' were also examined on 1,211 subjects. The spinal canal diameter in sagittal images for all ages at the C5/6 intervertebral disc level was 11.7±1.6 mm in males and 11.6±1.5 mm in females, while that at the C5 vertebral body level was 12.9±1.4 mm in males and 12.5±1.3 mm in females. Dural tube diameter in sagittal images for all ages at the C5/6 intervertebral disc level was 9.5±1.8 mm in males and 9.6±1.6 mm in females, while that at the C5 vertebral body level was 11.2±1.4 mm in males and 11.1±1.4 mm in females. Dural tube area in axial images for all ages at the C5/6 intervertebral disc level was 155.7±32.1 mm2 in males and 149.6±29.0 mm2 in females, while that at the C5 vertebral body level was 187.4±32.6 mm2 in males and 177.0±32.7 mm2 in females. Spinal cord diameter in sagittal images for all ages at the C5/6 intervertebral disc level was 5.9±1.0 mm in males and 5.8±0.9 mm in females, while that at the C5 vertebral body level was 6.5±0.7 mm in males and 6.4±0.7 mm in females. Spinal cord area in axial images for all ages at the C5/6 intervertebral disc level was 70.6±11.7 mm2 in males and 68.9±11.3 mm2 in females, while that at the C5 vertebral body level it was 78.1±9.4 mm2 in males and 74.4±9.4 mm2 in females. The sagittal diameter of the spinal canal, and the sagittal diameter and axial area of the dural tube and spinal cord tended to decrease with age. This tendency was more marked at the intervertebral disc level than at the vertebral body level, especially around the C5/6 intervertebral disc level. The spinal cord occupation rate in the dural tube at the C5 vertebral body level averaged 58.3±7.0%. We propose that developmental stenosis of the cervical spinal canal in MRI can be defined as an occupation rate of the dural tube of more than 67%. Using this definition, developmental stenosis of the cervical spinal canal was present on MRI in 13% of subjects in this study. The average number of G and R test was 22.0±5.7 in right hand, 22.3±5.6 in left hand. The average number of 10 second step test was 19.7±3.4. The number of these tests decreased with age. Using MRI data, we established standard values for the cervical spinal canal, dural tube, and spinal cord for each gender and generation in the Japanese population. We propose a spinal cord occupation rate of greater than 67% of the dural tube based on MRI data as the criterion for diagnosing developmental stenosis of the cervical spinal canal. We established standard values for ''finger grip and release in 10 seconds (G and R test)'' and ''10 second step test'' in healthy Japanese subjects. (author)