An intervertebral disc is the shock absorber of our spine. Each disc is located between two vertebral bodies. These discs are made of a strong outer ligamentous ring called the annulus fibrosus and an inner jelly-like section called the nucleus pulposus. The annulus fibrosus and nucleus pulposus work together to evenly distribute pressure across the disc. An annular disc tear is a tear in the outer ligamentous ring. This ligament is composed of strong fibers which are highly innervated with pain receptors so when a tear does occur it can cause significant symptoms.
As the discs act as shock absorbers between the vertebrae, whenever there is a high impact activity, trauma, or exertional/straining movements this added pressure wears on the disc. With increased pressure the discs will start to break down, lose hydration and flexibility contributing to cracks and tears. Tears in the outer ring of the disc, the annulus fibrosus, can cause mild to severe pain depending on where the tear is located. Although annular tears can occur throughout the spine they are more common in the neck and low back as these are more mobile than the thoracic spine. The pain results from tearing of the ligamentous fibers, leading to inflammation which may aggravate surrounding neural structures.
As an example, imagine an intervertebral disc as a jelly filled donut. There is a jelly center, outer bread lining. Imagine squeezing a jelly filled donut very slightly. The jelly will start to seep through the pores of the bread but not expel outside of the donut completely. This is similar to an annular tear as explained above, the integrity is disrupted but the contents of the disc are still held inside the annulus.
Annular tears of the intervertebral disc can occur due to a many causes. Commonly they do occur as our discs naturally degenerate with age. When this occurs, the discs lose hydration and flexibility and therefore are at increased risk for tearing. Other factors contributing to annular tears include certain occupations or high impact activities putting intervertebral discs under added pressure.
Think of the disc as a rubber band, when new the rubber band stretches and then is able to return to normal. But with time, or more vigorous use or stretching it will start to crack and tear.
Here are a few examples of what can cause annular disc tears:
Most annular disc tears can cause pain ranging from mild to severe. The degree of pain often is directly related to the location and size of the tear.
Symptoms associated with an annular tear typically include:
Patients undergo a thorough medical history and comprehensive exam to evaluate their pain and symptoms. In addition x-ray imaging is used to evaluate a patients spinal anatomy and look for any underlying abnormalities. The imaging study of choice to evaluate for an annular tear is magnetic resonance imaging (MRI). This study evaluates the soft tissue structures. However there are some situations where tears are not visible on an MRI which is why the history and physical is so vital.
Most annular tears improve and heal over time with rest, spine-specialized physical therapy, and over the counter anti-inflammatories. In some situations symptoms may warrant prescription strength anti-inflammatories or possible pain or muscle relaxant medication.
Reviewed by: Dr. Christopher Good, MD, FACS.