Decreased disc height is one of the imaging manifestations of intervertebral disc degeneration, and a herniated disc can cause decreased disc height. The intervertebral disc is a fibrous tissue structure between the vertebrae, consisting of the annulus fibrosus, nucleus pulposus, and cartilage of the vertebral endplates, etc. The intervertebral disc mainly contains proteoglycans, water, and other substances, which play a supportive and cushioning role for the spine. When the intervertebral disc ruptures, crushes and damages, its constituent substances decline, resulting in reduced elasticity and pressure resistance, and imaging such as lumbar spine MRI examination can be manifested as a reduction in the height of the intervertebral disc. If intervertebral disc degeneration occurs, the decrease in disc height on imaging will gradually worsen. Herniated discs are mainly caused by degenerative discs, therefore, in lumbar spine MRI examination, not only can we see the lumbar disc herniation, but also can see the disc height is reduced.