Annular tears, refer to an injury to the disc that acts as a cushion between the vertebrae of the spine. The discs are present and acting as cushions in the cervical, thoracic, and lumbar portions of the spine.
The disc, simply speaking is made up of two parts, the soft center (nucleus) and the thick covering that wraps around (annulus) and contains the nucleus. The disc acts as a liquid filled cushion that is held in place with the thick covering that attaches to the bone of the vertebrae to hold everything in place. Our body weight is transmitted across the disc and cushioned by the nucleus. Our body rotation and twisting are restrained by the thick covering over the nucleus that is called the annulus and resembles a radial tire in its construction.
Squeeze on anything that is liquid filled and the same thing always happens, the liquid tries to squirt out somewhere. The same is true in the disc, the pressures generated in the nucleus can try to force the liquid filling out. If the annulus remained intact, there would be no escape of the soft nuclear material. However, the combination of strong forces applied to the annulus and a very poor blood supply to repair the annulus leads to a situation (degeneration) where tearing of the annulus occurs quite often. However, annular tearing doesn’t always mean that there will be pain.
There are 3 patterns of annular tearing; radial, concentric, and peripheral. Each of these occur in different locations of the annulus, age groups and are correlated with a different problem and prognosis. Radial tearing is very common and even has a number classification to designate severity. (see Dallas Classification) It can be seen that the tear extends from the interior of the disc to the exterior and can allow passage of disc fragments from inside the disc to outside the disc where they can come in contact with the nerves and spinal cord.
If you have chronic recurrent low back (or neck pain) that stays steady or comes and goes, an annular tear may be the reason. Now that you know a what an annular tear is, let’s take a look at why they hurt.
There are four main reasons that annular tears hurt.
- There is just not enough blood supply to the annulus to allow healing. This is further aggravated by the fact that the disc is almost always moving.
- The tear may not be able to heal itself because some disc material is wedged in the tear so that the edges cannot approximate.
- A high-grade tear may allow passage of inflammatory chemical mediators from the inside of the disc (nucleus) to the outer 1/3 of the annulus where there are nerves that are very sensitive to these chemicals.
Healing of an annular tear occurs from the outside in and carries sensitive nerve tissue in addition to new blood vessels.
The presence of these chemical mediators inside the disc can even cause leg pain if the chemicals leak out of the disc and come in contact with the nerve, even with a normal appearing disc! On the other hand around 30% of people who have never had back or neck pain have documented annular tears.
How do you know if you have an annular tear? Most people find out that they have an annular tear because they have persistent back pain and get an MRI scan that reads “annular tear or high intensity zone (HIZ)”. The most accurate way to see an annular tear is to get a discogram followed by a CT scan that shows the size and extent of the tear by the dye seen. A provocative discogram can also tell if a tear is painful. (Remember that annular tears are asymptomatic about 30% of the time.
- There are four described Treatment Options.These tears can take 18-24 months to heal. The blood supply is poor and the motion forces are high around the annulus, so do nothing or pursue any “hands on” treatment such as physical therapy, exercise, stretching, or axial decompression all of which I consider conservative (non-operative).
- A chemical injection has been described to inject into the disc by Drs. Klein, Eek and Mooney.
- Endoscopic discectomy can remove loose fragments in the disc and reduce pressure that may be forcing disc material into the tear.
- A disc replacement/fusion may be contemplated.
Dr. Tony’s advice: “Time is on your side, proceed slowly, stage your treatment, annular tears can test your fortitude.”