An intervertebral disc is a strong ligament that connects one vertebral bone to the next. The discs are the shock-absorbing cushions between each vertebra of the spine. Each disc has a strong outer ring of fibers, called the annulus fibrosus, and a soft, jelly-like center, called the nucleus pulposus. The annulus is the strongest area of the disc and connects each vertebra together. The strong annular fibers contain the nucleus and distribute pressure evenly across the disc. The nucleus, or center of the disc, is hydrated and serves as the main shock absorber. The nucleus absorbs the impact of the body's daily activities and keeps the two vertebrae separated.
Just like other ligaments, the discs can be injured. The annulus can tear or rupture anywhere around the disc. If it tears and no disc material is ruptured, this is called an annular tear. The outer 1/3 of the disc’s annular ring is highly innervated with pain fibers. Thus, if a tear involves the outer 1/3 it may be extremely painful. This tear will heal with scar tissue over time but is more prone to future tears and injury. Studies also indicate that annular tears may lead to premature degeneration of the disc, endplates, and facet joints.
Annular Tear Causes
Most annular tears are caused by the natural aging process. Since the neck and back are responsible for bearing most of a person’s body weight, they are susceptible to a great deal of wear over time. By the age of 30, most people’s intervertebral discs have begun to degenerate to a certain degree. This degeneration can lead to annular tears with repetitive motion since the annulus is in a weakened state. Traumatic injury can cause an annular tear. This is typically seen in high-impact sports such as gymnastics and football and in people with strenuous occupations.
Annular Tear Symptoms
Predominant symptoms in many patients with an annular tear in the low back include midline back pain in excess of leg pain. Pain is often worse when sitting compared to standing, and positions that load pressure on the disc (coughing, sneezing, forward bending and lifting) tend to aggravate symptoms.
Diagnosing Annular Tears
After a physical assessment, a doctor will typically perform one or more diagnostic tests to localize the likely source of your pain. An MRI scan can be used to visualize an intervertebral disc, but annular tears may not always be seen. Occasionally your doctor may suggest a discography test to see if the disc is truly the source of pain. The procedure is performed under x-ray guidance and allows your physician to assess the integrity of the disc and monitor your experience of pain at the same time.