Study Design: Cervical herniated disc tissue obtained at surgery for myelopathy and intervertebral discs from autopsy cases were examined histologically.
Objectives: To clarify the characteristic histology of cervical disc herniation and the processes by which herniated masses are produced.
Summary of Background Data: Except for nucleus pulposus or anulus fibrosus, no other disc tissue has been described histologically in the cervical spine.
Methods: Twenty-one herniated cervical discs from 20 surgical cases (patients aged 37-68 years) and mid-sagittal slabs of 135 cervical discs from 41 autopsy cases (aged 20-85 years) were examined histologically.
Results: All the surgical specimens had cartilaginous endplate fragments together with nucleus pulposus or anulus fibrosus. Of the autopsy disc specimens, 61% had a horizontal cleft longer than two thirds of the anteroposterior diameter of the disc, and 49% had one or more vertical clefts extending to the cartilaginous endplate. Thirty-three percent showed separation of the cartilaginous endplate, and 15% had a herniated mass including parts of the cartilaginous endplate. These abnormal features increased with aging. The same order of decreasing frequency from horizontal cleft formation through herniation was observed in all decades.
Conclusions: The cartilaginous endplate-type of herniation is the predominant type of herniation in the cervical spine. It results from horizontal and vertical cleft formations of the disc.