If you're one of the 60-80% of people who will at some point experience back pain, you may find that one or more of your spinal discs is responsible. Spinal disc pain is common in people with back troubles, affecting about forty percent of cases.
The intervertebral disc is one of a number of spinal structures doctors and pain experts call "pain generators." Essentially, pain generators are places in the body where abnormal physiological activity gives rise to pain.
When it comes to spinal intervertebral discs as pain generators, 3 main types of abnormal activity, or pain generators, are possible.
The first occurs when the disc structure is injured from the outside. Classic examples of this type include disc herniation and annular tear.
A disc herniation occurs when the soft, jelly-like substance located on the inside of the disc bulges or breaks through the strong outer binding, which is made of tough fibers. Pain may occur if that substance, called the nucleus pulposus, comes into contact with a spinal nerve root.
One common way people herniate their discs is by lifting heavy objects with a rounded spine, in other words not bending the knees to lift, and twisting the spine at the same time. Spinal disc herniation often occurs in younger adults between the ages of 18 and 35 when the water content of the disc is still high.
An annular tear is a fraying of the tough outer fibers that surround the nucleus pulposus.
According to Dr. Alexander Vaccaro, Professor of Orthopedic Surgery at Thomas Jefferson University and Rothman Institute in Philadelphia, PA, not only does the annulus fibrosus consist of strong connective tissue fibers, but it contains nerve fibers which are capable of communicating pain, as well. These communication-ready nerve fibers are found toward the outside of the disc.
Vaccaro notes that normal nerve fibers capable of transmitting pain signals have not been found more deeply in the disc. But a variety of substances capable of bringing about pain have. These substances include prostaglandins, lactic acid, and substance P. And, as discs degenerate, says Vaccaro, nerve ingrowth has been observed — both in the internal-most fibers of the annulus and in the nucleus. Vaccaro reports that this extra nerve growth located inside a degenerating disc may significantly add to your pain.
The second type of abnormal activity in a disc that can lead to pain is due to a condition known as internal disc disruption, or IDD for short. Note that IDD is not the same as degenerative disc disease. While degenerative disc disease is due to normal age-related changes that go on in the spine, IDD involves internal changes associated with degeneration of the nucleus pulposus. (Remember, the nucleus pulposus is that soft jelly-like substance located in the center of the disc.) This particular type of degeneration can extend to the innermost fibers of the annulus that surrounds the nucleus. Unlike disc herniation and annular tear, both mentioned above, IDD-related degenerative changes do not reach the outer fibers of the annulus.
When you have IDD, your disc may seem perfectly normal while changes may be occurring inside the nucleus as well as the annulus.
Whether your disc pain comes from outer impact or internal changes, most likely forward and backward movement of your spine, called flexion and extension, respectively, will bring on the greatest pain, according to a 2001 study published in the journal Pain Practitioner.
A third reason your discs may cause pain is infection. This topic is mostly beyond the scope of this article. See your doctor as soon as you can if you suspect any type of disc pain, but as soon as you possibly can if infection cannot be ruled out as a cause.
Of course, the treatment for each underlying cause of disc pain will likely differ. It's important to clearly and thoroughly communicate your symptoms to your doctor so she can accurately determine what needs to be treated. That said, a 2018 study published in the Spine Journal concluded that people who had surgery for lumbar disc herniation could expect improvement in their back pain even a year out. The study also found that leg pain and disability status also improved significantly.