The “dehydrated” lumbar intervertebral disk on MR, its anatomy, biochemistry and biomechanics

Excerpt

MR imaging of the lumbar spine often reveals disks with lower than normal signal in the nucleus pulposus without decreased disk height or abnormal contours of the annulus fibrosus. These are often referred to as “dehydrated”, “desiccated” or “dark” disks. The clinical significance of dehydrated disks may not be generally known. Official reports of MR images tend to emphasize the appearance of disk margins rather than signal intensity in the disks. Bulging disks and protrusions may be considered generally more clinically significant than dark disks. Furthermore, scientific studies in the radiologic literature on the subject of dark disks seem to be few. Therefore, a review of the current knowledge regarding the dark disk seemed both necessary and timely. The purpose of this communication is to review briefly the morphologic, biochemical and biomechanical features of the dark disk and its potential to cause low back pain or radiculopathy. …