DEGENERATIVE DISC DISEASE

Degenerative Disc Disease

An Overview

If you’ve been diagnosed with degenerative disc disease (DDD), you’re probably worried about how you’ll live with the condition. Will it hinder your lifestyle or your participation in your favorite activities? Will you be in constant pain, or can you live comfortably? Will you be able to find any relief whatsoever?

Degenerative Disc Disease with Spondylolisthesis

While hearing those three “D” words may send you into a panic, you can rest assured that the condition isn’t quite as terrifying as the name makes it seem. The term “degenerative disc disease” is a bit of a misnomer. DDD is not a disease in the traditional sense, but a commonly diagnosed degenerative condition involving one or more damaged intervertebral discs that can occasionally cause back or neck pain. Additionally, many people interpret “degenerative” to mean that the symptoms associated with the condition worsen over time, but the word is intended to describe the progressive deterioration of one or more discs, not the increasing intensity of symptoms.

That said, you should also know that almost everyone will have some form of spinal degeneration by middle to advanced age, and most individuals exhibiting signs of DDD in an X-ray or MRI will never experience symptoms. The majority of patients who do develop symptoms will experience mild to moderate discomfort, while the condition can be quite painful for a small percentage of the population.

An Anatomical Look at the Spine

So, what does having degenerative disc disease mean for you? You likely want to find out how the condition developed in the first place, as well as figure out how to deal with its effects. Before we delve into the specifics of DDD and answer those questions, let’s take a quick look at the anatomy of the spine:

Vertebrae – Vertebrae is the stacked, bony building blocks of the spinal column. The spinal column begins at the base of the skull, continues through the neck (cervical region), the mid-back (thoracic part), the lower back (lumbar region), and ends in the buttocks with the sacrum and coccyx (tailbone). Generally, a human spine has 24 individual vertebrae plus several fused vertebrae in the pelvic region.
Intervertebral discs – Between the vertebral bones are intervertebral discs. Discs are pads of cartilage and collagen that act as shock absorbers for the spine. Two stacked vertebrae and one intervertebral disc make up a vertebral motion segment.
Facet joints – A vertebral segment also includes two sets of facet joints that connect the individual vertebrae. Facet joints and discs, along with muscles and ligaments, are all components that allow the spine to perform a wide array of complex movements.
Spinal cord and nerve roots – While the movement is an essential function of the spinal column, its primary job is to protect the spinal cord, which runs through the spinal canal from the base of the brain into the lower back. Nerve roots branch off the spinal cord and exit the spinal column through foramina (canals formed by vertebrae) to innervate other areas of the body.

Understanding Degenerative Disc Disease

Based on our description of the spinal column, it may seem that it is sturdy and impervious to damage. However, the spine’s anatomical components are quite delicate and sophisticated in their design, which means the spine is naturally susceptible to wear and tear and the onset of degenerative conditions. As one of the most common of these conditions, degenerative disc disease can be an indicator of additional spinal degeneration, mainly because the deterioration of a disc often sets off a chain reaction of problems in the spine.

This “degenerative cascade” theory, as introduced by Dr. William Kirkaldy-Willis in the 1970s, was the first to unify multiple opinions on the progression of lumbar (lower) spine degeneration. While degenerative processes can take place at any level of the spine, the lower back is especially prone to wear and tear due to its weight-bearing responsibilities and wide range of motion.

The changes associated with DDD typically begin with the dehydration of an intervertebral disc. Microtrauma (small injuries), caused by seemingly inconsequential rotational or flexion movements or force, can lead to the formation of tiny tears or fissures in a disc’s outer wall (annulus fibrosus). This can lead to scar tissue formation along the disc wall. Additional tearing and scar tissue buildup can eventually:

Damage or irritate the nerves that innervate the outer one-third of a disc, causing pain
Interfere with normal nutrient absorption and waste removal from a disc
Cause the nucleus pulposus (the gelatinous inner core of a disc) to lose water content
Compromise the overall structural integrity of the annulus fibrosus

As a disc deteriorates further, the annulus fibrosus can no longer effectively withstand motion in the spine, yet pressure continues to be exerted on the inner nucleus pulposus of the disc. In some cases, this intradiscal pressure can cause the disc wall to bulge outward beyond its healthy boundaries, forming a bulging disc. In other instances, a fissure can develop in the outer wall, and inner disc material may leak out, releasing highly inflammatory proteins from the core. These proteins can irritate nerves in the disc wall and can cause pain. Furthermore, a damaged disc can move slightly out of place as it becomes more and more unstable. The body can trigger muscle spasms as a response to inflammation and micro-motion to restore stability to the affected vertebral segment. Muscle spasm itself can cause significant discomfort.

Unlike many other tissues in the body, a disc cannot repair itself once it has been damaged. As disc deterioration progresses, the disc can shrink in size. Disc shrinkage forces the vertebrae directly above and below the disc to move closer together, which can lead to increased stress on the facet joints.

Remember that two sets of facet joints connect two vertebrae in a vertebral motion segment. A damaged disc can no longer support its adjacent vertebrae properly, which means the facet joints are forced to shift into an abnormal position and perform their motions awkwardly. This can cause other areas of the spine to adjust into an abnormal position to adapt to the awkward facet joint movement of the affected vertebral segment. Additionally, facet joint cartilage – which usually makes joint movement smooth and comfortable – can wear away at an accelerated pace because of the misalignment.

The degenerative cascade continues with the eventual complete disintegration of the facet joint cartilage. Facet joints can become inflamed and painful as the cartilage wears away and bone rubs on bone. This condition is known as facet joint disease, or spinal osteoarthritis, and is characterized by stiffness, tenderness, and a reduced range of motion. As affected facet joints and vertebral bodies rub together, bone spurs, or osteophytes, can form along the edges of vertebrae and in the joints themselves. Bone spurs, much like muscle spasms, are the body’s attempt to restore stability within a weakened vertebral segment. These bony growths, although not painful in and of themselves, can cause nerve compression symptoms if one or more comes into contact with the spinal cord or nerve roots.

Degenerative disc disease doesn’t follow an exact timeline or affect every individual in the same way, but Kirkaldy-Willis estimated that the degenerative cascade process takes somewhere between 20 and 30 years to complete. As scary as degenerative disc disease and its related conditions may seem, you can take comfort in knowing that a majority of individuals will exhibit some form of spinal degeneration by the age of 60. In other words, you are not alone.

Causes and Risk Factors of Degenerative Disc Disease

We know that the development of DDD begins with the dehydration and weakening of intervertebral discs, which can occur over some time. We also know that repeated microtrauma can cause tearing in the annular wall of a disc and contribute to its deterioration. Even with this information, it is still difficult to pin down one exact cause or another for the condition, so it’s best to approach this section with an understanding that degenerative disc disease develops as the result of several causative factors.

That said, aging is one of the most common causes of degenerative disc disease. The discs are usually the first of the spinal components to begin deteriorating due to dehydration. Discs are made up of nearly 80 percent water, along with a matrix of collagen fibers and water-attracting proteoglycan protein molecules. These components are what make healthy discs pliable and able to withstand significant amounts of pressure. Since discs have no direct blood supply of their own, they must rely on the blood supply of nearby tissues and an abundance of water to transfer nutrients and remove waste material, processes that are essential to the health of the disc. Over many years, a disc can become less permeable, and the supportive matrix of collagen and protein can suffer; as a result, leading to the deterioration and eventual collapse of the disc itself.

In addition to aging, degenerative disc disease can also be caused by:

Lifestyle choices and habits – While it may seem odd to link your lifestyle and habits with your back pain, many studies have revealed a connection with the presence of degenerative discs to excessive alcohol and tobacco use. Both alcohol and tobacco products release toxins into the body that must be filtered out. However, excessive, habitual use can cause a buildup of toxins in the body, leaving cartilaginous areas like intervertebral discs particularly susceptible to damage.

Weight gain – Carrying excessive weight, particularly in the abdominal region, can seriously affect the health of the spinal components. Extra weight places added stress on the spine, forcing the discs, facet joints, ligaments, and muscles to work harder than necessary to provide proper support to the body. The added stress of extra weight placed on the discs, sometimes in combination with improper lifting techniques or a sudden twist or turn, can cause disc degeneration, bulging, or herniation.

Injury – Like any other area of the body, the intervertebral discs can be injured. Blunt force trauma, be it from a fall, a car accident, or even playing contact sports, can cause hidden damage to a disc structure that surfaces years later as a degenerating, bulging, or herniated disc. Sometimes, immediate disc damage occurs if the force applied to the spine is strong enough, as when a quarterback takes a particularly violent hit from a linebacker, or a gymnast slips and falls from the uneven bars.

Occupation – Many jobs require repetitive heavy lifting, bending, twisting, and turning. The spine is well equipped to perform these movements, but poor lifting techniques and improper body movement can cause microtrauma to the intervertebral discs and contribute to deterioration. Prolonged sitting while driving or at a desk can also cause spinal issues, mainly because the spine withstands three times the load force when in a sitting position versus standing.

Symptoms of Degenerative Disc Disease: More than Back & Neck Pain

Since degenerative disc disease can vary so widely from one individual from another, the symptoms you may experience could be completely different from those of another person. Regardless of your unique situation, it’s essential to be able to identify some of the core symptoms associated with the condition.

Looking back, we’ve learned that a deteriorating disc at any level of the spine can be painful on its own, due to irritated nerve fibers within the disc, micro-motion, and the release of inflammatory proteins. For a damaged disc in the cervical region of the spine, this pain is felt in the neck, whereas a degenerative lumbar disc can cause low back pain. Additionally, lower back pain can increase while sitting but may decrease while lying down.

Should damaged disc material come into contact with the spinal cord or a nerve root,, an entirely different set of additional symptoms can arise. Radiculopathy, or traveling nerve pain, is a frequently observed symptom associated with disc degeneration. Many times, patients with DDD complain of arm pain or leg pain and may attempt to treat those areas precisely when, in reality, a bulging or herniated disc in the spine is to blame. This phenomenon can be attributed to the way the nerves travel throughout the body.

The spinal cord has nerve roots that branch off into various body parts. If a nerve root is compressed by disc material or bone spurs in the neck, the following may be experienced:

Symptoms of pain that travel down through the shoulder, arm, hand, and fingers on one side.
Arm muscles feel weak and spastic.
Tingling and numbness in the arm and hand which can make picking up an object difficult.
Chronic headaches.

Similarly, radiculopathy that originates in the lumbar spine can lead to the following symptoms:

Pain that shoots down one side of the body, affecting the hips, buttocks, legs, and feet.
Muscle weakness, numbness, and tingling in a leg and foot, which can also make walking painful.
Foot drop, or the inability or difficulty in lifting the front part of afoot.

Generally, most of those who do experience symptoms associated with DDD feel mild, chronic pain or discomfort with occasional flare-ups, especially in the early stages of the condition. These fleeting episodes tend to be more painful than the baseline discomfort and can last a few days or as long as several months. Surprisingly, the symptoms associated with degenerative disc disease can diminish with age. This is usually due to the eventual collapse of a dehydrated disc, whose inflammatory proteins are entirely dried up and can no longer irritate disc nerve fibers, nerve roots, or the spinal cord. Disc collapse also eliminates micro-motion and permanently stabilizes the affected vertebral segment. Of course, disc collapse can lead to a new set of issues, such as additional bone spur growth and loss of mobility.

If you’ve been diagnosed with degenerative disc disease, there is no need to be alarmed. The earlier that DDD is detected, the better chance you have of improving your spinal health and delaying the later phases of the degenerative cascade. Taking time to educate yourself about the condition, its causes, and symptoms can help you approach your situation with a fresh, optimistic perspective.