Disc Tear (Annular Tear)
A disc- or annular- tear (or fissure) represents a degenerative or traumatic change in an interveterbral disc. These tears involve separations or breaks in the fibers comprising the annulus fibrosus, or the fibrous outer-most portion of an intervertebral disc. These fibers run radially (outward from the center), transversely (lying across), and concentrically (circularly, progressively more distant from the center), much like the layers of an onion. Together they form layers of fibrous tissue that surround the internal portions of the disc.
A disc tear is distinct from disc degeneration or disc herniation (a slipped disc). When portions of the annulus fibrosus tear, the integrity of the disc becomes compromised; this can cause pathology such as bulging, prolapsed and more which can compress local structures. However, it is not until the tear completely opens a channel for the innermost substance to leave the disc entirely that a herniation has occurred.
Disc tears can result in back pain, which has been estimated to affect between 12-35% of the population in the western world. Tears can be a result of disc degeneration and can result in subsequent herniation. Tears and disc degeneration can begin to accumulate very early. This degeneration increases with age. It’s important to note than degeneration does not necessarily imply a pathologic process, or that trauma is a prerequisite. While trauma can cause tearing, many of these disc tears are merely the result of aging. It is equally important to note that while disc tears may cause pain, they are often asymptomatic.
The spine consists of a column of bones, known as vertebrae, which are stacked atop one another from the pelvis to the base of the skull, protecting the spinal cord. Intervertebral discs lie in between these vertebrae, connecting the bones together and forming the primary joints of the spine. These discs support upper-body weight and muscle activity allowing for motion such as bending and flexing. The discs themselves consist of the tough annulus fibrosus which contains a gel-like inner portion called the nucleus pulposus. These intervertebral discs contain few blood vessels, but do have nerves in the outermost layers of the annulus fibrosus.