What is the first step of intervertebral disc degeneration?

The process of intervertebral disc degeneration begins with changes in the disc that ultimately lead to a loss of its structural integrity and function. The correct answer indicates that the initial stage of degeneration is characterized by the disc undergoing biochemical and mechanical alterations.

In this early phase, the nucleus pulposus, which is the gel-like center of the disc, begins to lose hydration and the disc may experience altered cellular activity. This can lead to a variety of changes, but typically it is a deterioration in the disc's overall health and function that marks the beginning of degeneration.

In contrast, bulging and herniation are more advanced stages that occur following the initial degenerative changes. These conditions are indicative of further progression where the disc may protrude beyond its normal boundaries or develop fissures, respectively. Thinning, while it can be a characteristic seen in degeneration, typically reflects a later stage where the disc has already experienced significant changes and loss of height.

Thus, recognizing the initial step as the degenerated disc fits within the broader context of understanding the continuum of intervertebral disc degeneration and its subsequent complications.