Disc dehydration

Disc dehydration is one of the earliest and most characteristic degenerative changes of the intervertebral disc, in which the water content of the nucleus pulposus, the central gelatinous structure of the disc responsible for the absorption and distribution of mechanical loads, gradually decreases. Normal aging is the main cause of disc dehydration, as the concentration of proteoglycans within the nucleus decreases over time, which are substances with a strong capacity to bind water, while this process may be accelerated by factors such as smoking, chronic mechanical stress, trauma, and genetic factors. The reduction in water content leads to a progressive loss of the disc’s elasticity and shock-absorbing capacity, resulting in decreased disc height and increased susceptibility to further degenerative changes, such as annulus fibrosus tears, disc protrusion, or disc herniation. On magnetic resonance imaging, disc dehydration is identified by reduced signal intensity on T2-weighted sequences, a finding that reflects the decreased water content and is often used for the classification of the severity of degenerative disc disease. Although disc dehydration is largely an expected finding with advancing age and may be asymptomatic, in some patients it is associated with chronic pain, particularly when accompanied by significant loss of disc height or other associated degenerative changes.