What is the Difference Between a Disk Herniation and a Disk Bulge?

The word “herniation” gives the impression of a traumatic injury. The term “bulge” implies a smaller or more chronic problem.

In the human spine, a disk herniation occurs when there is a tear in the covering of a disk. When material from the center of the disk passes through this tear, a localized sometimes mushroom shaped collection of disk material causes a mass that can press on the nerves of the spine, resulting in a “disk herniation.”

A disk bulge is caused by a weakening of the covering of a disk involving most or all of the covering. Disk material presses on this weakened cover, causing a “bulge” of the disk, which also can press on the nerves of the spine.

A disk bulge usually develops over a long period of time due to aging or arthritis though can also occur due to many small traumas over time.

On imaging studies a disk herniation involves a smaller amount of the covering of the disk than a disk bulge. A disk bulge tends to involve most of the diameter of the covering of the disk. A herniation can be small or very large. There is always a limit to the size of a disk bulge before it becomes a herniation.

The covering of the disk is called the “annulus fibrosis.”

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