What is degenerative disc disease?

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1 What is degenerative disc disease? Degenerative disc disease is one of the most common causes of low back pain, and also one of the most misunderstood. Many patients diagnosed with low back pain caused by degenerative disc disease are left wondering exactly what this diagnosis means for them. Common questions that are often on patients minds include: If I have low back pain from degenerative disc disease in my thirties, how much worse will it become with age? Will the degenerative disc disease become a crippling condition? Will I end up in a wheelchair? Should I restrict my activities? Can I still play sports? Will the degenerative disc disease spread to other parts of the spine? Will the low back pain from degenerative disc disease cause any permanent damage? Degenerative disc disease is a misnomer A large part of many patients confusion is that the term degenerative disc disease sounds like a progressive, very threatening condition. However, this condition is not strictly degenerative and is not really a disease: Part of the confusion probably comes from the term "degenerative", which implies to most people that the symptoms will get worse with age. The term applies to the disc degenerating, but does not apply to the symptoms. While it is true that the disc degeneration is likely to progress over time, the low back pain from degenerative disc disease usually does not get worse and in fact usually gets better over time. Another source of confusion is probably created by the term "disease", which is actually a misnomer. Degenerative disc disease is not really a disease at all, but rather a degenerative condition that at times can produce pain from a damaged disc. Disc degeneration is a natural part of aging and over time all people will exhibit changes in their discs consistent with a greater or lesser degree of degeneration. However, not all people will develop symptoms. In fact, degenerative disc disease is quite variable in its nature and severity. Medical practitioners disagree on degenerative disc disease Finally, many patients are confused about degenerative disc disease because many medical

2 professionals don t agree on what the phrase describes. In practical terms, this means that few practitioners agree on what does and does not constitute a diagnosis of degenerative disc disease. Even medical textbooks don t usually attempt to give an accurate description. Therefore, while many practitioners believe that degenerative disc disease is a common cause of low back pain in young adults, very few agree on the implications. While there is still a lot of debate in the medical community about degenerative disc disease, a few aspects of the condition are known. This article will discuss aspects of degenerative disc disease that are more commonly accepted, such as the theory of the degenerative cascade, as well as some areas of theory that are still a source of debate in the medical community. Pain from degenerative disc disease Low back pain from a degenerated disc The lumbar disc is a unique and well-designed structure in the spine. It is strong enough to resist terrific forces in multiple different planes of motion, yet it is still very mobile. The disc has several functions, including acting as a shock absorber between the vertebral bodies. The lumbar disc has been likened to a jelly donut. It is comprised of a series of bands that form a tough outer layer and soft, jelly-like material contained within: Annulus fibrosus the disc s firm, tough outer layer Nerves to the disc space only penetrate into the very outer portion of the annulus fibrosus. Even though there is little innervation to the disc, it can become a significant source of back pain if a tear in the annulus reaches the outer portion and the nerves become sensitized. With continued degeneration, the nerves on the periphery of the disc will actually grow further into the disc space and become a source of pain. Nucleus pulposus the jelly-like inner disc material The nucleus pulposus contains a great deal of very inflammatory proteins. If this inner disc material comes in contact with a nerve root, it will inflame the nerve root and create pain down the leg (sciatica or radiculopathy). In the same manner, if any of the inflammatory proteins within the disc space leak out to the outer annulus and touch the pain fibers in this area, it can create a lot of low back pain. Source of the pain Generally, the pain associated with degenerative disc disease is thought to stem from two different factors: Inflammation Abnormal micromotion instability The proteins in the disc space can cause a lot of inflammation, and inflammation in the disc space can lead to low back pain radiating to the hips. The associated pain can also travel down the back of the legs.

3 If the annulus the outer rings of the intervertebral disc - becomes damaged or worn down, it is not as effective in resisting motion in the spine. This condition has been termed micromotion instability because it is usually not associated with gross instability (such as a slipped vertebral body or spondylolisthesis). Both the inflammation and micromotion instability can cause muscular spasm in the low back. The muscle spasm is the body s attempt to stabilize the low back. It is a reflex, and although the body s response of muscle spasm is not necessary for the safety of the nerve roots, it can be quite painful. The "degenerative cascade" of a degenerating disc There is minimal blood supply to the disc, and blood is what brings healing nutrients and oxygen to damaged structures in the body. This means that the spinal disc lacks any significant reparative powers. Unlike muscles, which have good blood supply, once a spinal disc is injured it cannot repair itself. Stages of degenerative disc disease In the 1970 s, Kirkaldy-Willis first described the "degenerative cascade" of degenerative disc disease. He postulated that after an individual suffers a torsional (twisting) injury to the disc, the disc would degenerate in three general stages. First, there is significant dysfunction caused by the acute back pain of the injury. Next, there is a long phase of relative instability at that particular vertebral segment and the patient will be prone to intermittent bouts of back pain. Finally, the body re-stabilizes the segment and the patient experiences fewer episodes of back pain. Based on the observation that demographic studies show less back pain from degenerative disc disease in elderly adults (over 60 years) than in younger adults (30 to 50 year-olds), he also concluded that this process happened over a period of 20 to 30 years. Although elderly patients may have pain from facet osteoarthritis, it is uncommon for them to have disc problems. While this summary is a simplification of Kirkaldy-Willis s extensive work, it lays the framework for what is known today. We do know that lumbar disc degeneration is a very common and natural process, and only in limited cases does it become painful. Degenerative disc disease and low back pain The natural history of lumbar degenerative disc disease is relatively benign. The pain tends to be intermittent, and although at times the pain may seem to be getting worse, the painful symptoms are generally not progressive. While the disc degeneration will progress, the low back pain and other symptoms do not tend to get worse with the progression of the degeneration.

4 Many patients worry that if they are have a lot of low back pain when they are only 35 years old, the pain will become much worse and they may be in a wheelchair by the time they re in their sixties. However, if patients can find a way to manage their back pain and maintain their function, the natural history is really quite favorable. With continued disc degeneration, all the inflammatory proteins within the disc space will eventually burn out, and the disc will usually become stiffer, thus decreasing micro-motion. In fact, someone who is 65 years old is actually less likely to have discogenic back pain than someone who is 35 years old. Degenerative disc disease: the natural degenerative process Normal disc degeneration with age When we are born, the disc is comprised of about 80% water, which gives it its spongy quality and allows it to function as a shock absorber. As we age, the water content decreases and the disc becomes less capable of acting as a shock absorber (see Figure 1). The proteins within the disc space also change composition, and most of us will develop tears into the annulus fibrosus (the outer hard core of the disc). Most people will have some level of disc degeneration by their sixth decade, yet most do not have back pain (see Figure 2). Magnetic Resonance Imaging (MRI scan) has contributed a great deal to our understanding of lumbar degenerative disc disease and the natural degenerative process. With the advent of MRI technology, good anatomic detail of the disc can be imaged and correlated with the individual s back pain. Through studies with MRI scans, it was found that: A large number of young patients with chronic low back pain had evidence of disc degeneration on their MRI scans, and; Up to 30% of young healthy adults with no back pain had disc degeneration on their MRI scans. Therefore, degeneration on an MRI scan cannot be used as the sole diagnostic tool for lumbar degenerative disc disease. Disc degeneration present on an MRI scan is not synonymous with a diagnosis of degenerative disc disease and low back pain. The MRI findings need to be corroborated by the findings of the patient s history and physical exam. Pain from degenerative disc disease It is not exactly clear why some degenerated discs are painful and some are not. As with many common causes of back pain, there is probably a variety of reasons that discs can become painful. Some theories about pain from degenerative disc disease are: If a disc is injured or degenerated, it may become painful because of the resultant instability from the disc injury, which in turn can lead to an inflammatory reaction which results in low back pain. Some people seem to have nerve endings that penetrate more deeply into the outer annulus than others, and this is thought to make the degenerated disc more susceptible to becoming a pain generator.

5 MRI findings without significant degenerative disc disease The two findings most correlated with a pathological disc a degenerating disc that is painful are: 1. Disc space collapse 2. Cartilagenous end plate corrosion The cartilagenous end plate is the source of disc nutrition. If this becomes eroded, the disc is likely to go through a degenerative cascade leading to the inflammation and micromotion instability, which in turn causes pain. As it goes through the process, the disc space will collapse. MRI findings of disc dehydration (often referred to as a dark disc, because a disc with less water in it looks dark on an MRI scan), annular tears, or disc bulges are not specific causes of low back pain. These findings may or may not be the cause of the patient s low back pain. It is well known that the results of surgically fusing a spine with these findings will be much more unreliable than fusing a disc space that has disc space collapse and cartilagenous endplate erosion. Common symptoms of degenerative disc disease Along with MRI scan results that show disc degeneration, there are some common symptoms that are fairly consistent for people with low back pain from degenerative disc disease. The typical individual with degenerative disc disease is an active and otherwise healthy person who is in their thirties or forties. In general, the patient s pain should not be continuous and severe. If it is, then other diagnoses must be considered. Degenerative disc disease pain is usually more related to activity and will flare up at times but then return to a low grade pain level or the pain will go away entirely. Common symptoms of degenerative disc disease include: The low back pain is generally made worse with sitting, since in the seated position the lumbosacral discs are loaded three times more than standing. Certain types of activity will usually worsen the low back pain, especially bending, lifting and twisting. Walking, and even running, may actually feel better than prolonged sitting or standing. Patients will generally feel better if they can change positions frequently, and lying down is usually the best position since this relieves stress on the disc space. Types of pain from degenerative disc disease Most patients with degenerative disc disease will have some underlying chronic low back pain, with intermittent episodes of severe low back pain. The exact cause of these severe episodes of

6 pain is not known, but it has been theorized that it is due to abnormal micro-motion in the degenerated disc that spurs an inflammatory reaction. In an attempt to stabilize the spine and decrease the micro-motion, the body reacts to the disc pain with muscle spasms. The reactive spasms are what make patients feel like their back has "gone out". The severe episodes of low back pain from degenerative disc disease will generally last from a few days to a few months before the patient goes back to their baseline level of chronic pain. The amount of chronic pain is quite variable and can range from a nagging level of irritation to severe and disabling pain, although severe, disabling pain is quite rare. In addition to low back pain from degenerative disc disease, there may be leg pain, numbness and tingling. Even without pressure on the nerve root (a "pinched nerve"), other structures in the back can refer pain down the rear and into the legs. The nerves can become sensitized with inflammation from the proteins within the disc space and produce the sensation of numbness/tingling. Generally, the pain does not go below the knee. These sensations, although worrisome and annoying, rarely indicate that there is any ongoing nerve root damage. However, any weakness in the leg muscles (such as foot drop) is an indicator of some nerve root damage. Chronic pain versus acute pain One very important tenet in chronic pain is that the level and extent of pain does not equal tissue damage. Severely degenerated discs may not produce much pain at all, and discs with little degeneration can produce severe pain. In this manner, chronic pain is very different from acute pain. With acute pain, the severity of pain directly correlates to the level of tissue damage. This provides us with a protective reflex, such as the reflex to remove your hand immediately if you put it on something hot. In chronic pain, the pain does not have the same meaning it is not protective and does not mean there is any ongoing tissue damage. Degenerative Disc Disease - Non-Surgical Treatment Options Introduction Degenerative disc disease is a common condition that afflicts many young adults. Although degenerative disc disease can cause symptoms of lower back pain over a long period of time, the good news is that the symptoms are usually manageable with various conservative, non-surgical treatment options. The treatment options for degenerative disc disease are either passive (done to the patient) or active (done by the patient). Usually a combination of treatments is used to help control the symptoms. Passive treatments are rarely effective on their own - some active component is almost always required. Common passive treatments include:

7 Medications Chiropractic/osteopathic manipulations Epidural injections TENS units Common active treatments include: Physical therapy (exercises, stretching) Quitting smoking Pain from degenerative disc disease is caused by instability at the motion segment and inflammation from the degenerated discs. Both the instability and the inflammation have to be addressed for the treatment to be effective. Mechanical instability from degenerative disc disease Exercises for patients with degenerative disc disease For the mechanical instability, dynamic lumbar stabilization exercises for patients with degenerative disc disease can help stabilize the spinal segments. Good muscular control of the spine can help compensate for a degenerated disc and reduce both instability and pain. These exercises, which are best learned with a physical therapist, consist of the following: Finding the position the spine is most comfortable in (neutral spine) Educating the back muscles to keep the spine in the neutral position Maintaining the neutral position through a series of movements that apply more and more degrees of freedom of motion. Two other important components of an active exercise program for those with degenerative disc disease are a daily hamstring stretching program and aerobic conditioning. 1. Hamstring stretching for degenerative disc disease Hamstring stretching is very important for patients who have degenerative disc disease. If these muscles are tight they lock the pelvis, causing all the motion and stress to be transmitted to the lumbosacral junction. If the hamstrings are kept stretched, the pelvis will be allowed to rotate and relieve some of the stress on the lower lumbar discs. Hamstrings are like any other tendon or muscle; the more often they are stretched the more effective the stretching will be. When stretching the muscle, seconds of continuous tension should be applied without bouncing (bouncing triggers a reflexive spasm in the muscle). Since hamstring stretching needs to be done every day, preferably twice a day, this activity should not be linked to other exercises that may be done less frequently. It is

8 easier to get into a stretching routine if you do the stretching at the same time every day, such as in the morning when you get up, and right before going to bed. 2. Aerobic conditioning for degenerative disc disease Conditioning is very important since it has been shown in large studies that individuals who are well conditioned have less pain than those who are deconditioned. The aerobic exercise should be low impact so that it is well tolerated by the back and degenerated discs. Walking is an excellent low impact aerobic exercise, and stationary biking and swimming are also good options. The goal of an exercise program for degenerative disc disease should be to work up to 30 to 60 minutes of exercise three times weekly, and the exercise needs to be continuous. A lot of patients walk at work and feel that further exercise is unnecessary. However, this stop and start type of activity is not adequate. There is actually a biochemical reaction the body generates with continuous aerobic activity, and it is thought that this reaction helps decrease pain. Anti-inflammatory medications and treatments for degenerative disc disease Anti-inflammatory medications for degenerative disc disease The most common treatments for inflammation from degenerative disc disease include NSAID s (such as Ibuprofen), oral steroids, or epidural steroids. Usually, NSAID s are sufficient for pain management and either oral or epidural steroids can be saved for more severe episodes of pain. Epidural injections for degenerative disc disease Epidural injections can also be used to help decrease inflammation in cases where there is a severe flair of pain from degenerative disc disease. The injection is done by inserting a needle into the space around the thecal sac (epidural space) and then injecting a steroid medication. This helps reduce inflammation in the spinal canal and can reduce pain in about 50% to 70% of patients. Exercise for degenerative disc disease Epidural injections should be thought of as part of the rehabilitation process from degenerative disc disease, and while the patient is feeling better exercises should be started for stretching, strengthening and aerobic conditioning. If the pain returns, the injection can be repeated up to three times in a 6-month period. Pain management for degenerative disc disease Medications for degenerative disc disease There are several medications that can be effective for pain management with degenerative disc disease, including:

9 1. Over-the-counter pain medicine such as acetaminophen (e.g. Tylenol) can help decrease pain associated with degenerative disc disease and can be used in conjunction with any of the anti-inflammatory medications. Actually, since its pain relief effect is totally different from anti-inflammatories, using both medications can be synergistic. Acetaminophen is such a good analgesic (pain reliever) it is put into most other commercially available narcotic pain relievers (e.g. Vicodin or Darvocet). 2. Narcotic pain relievers are all structurally related to heroin and are very effective at relieving pain, such as that from degenerative disc disease, in the short term. Unfortunately, they have a lot of side effects such as constipation and urinary retention, and have abuse potential. Many patients also have difficulty functioning while on the medication since it does affect ones cognitive abilities. Within about two weeks, continuous administration of oral narcotics leads to the body becoming habituated to the medication, so it does not seem to work as well. Many patients erroneously believe their pain from degenerative disc disease is getting worse since the medication does not seem to be effective, but they are just becoming habituated to the medication. In a minority of patients low dose chronic narcotic administration may be reasonable to help the patient function with less pain, but in most patients narcotics should only be used for postoperative discomfort, or briefly to help reduce pain for a patient who is having a severe flair of pain. Chiropractic/osteopathic manipulations for degenerative disc disease Chiropractic/osteopathic manipulations can be useful to relieve joint dysfunction in either the facet or sacroiliac joints that can be associated with the pain. Again, manipulations work best when combined with an active exercise program. Electrical stimulation for degenerative disc disease Electrical stimulation can sometimes be helpful to relieve back pain from degenerative disc disease, although there is little hard evidence in the literature to support its efficacy. It does, however, seem to reduce pain for some patients and helps them function better with less medication. An example of electrical stimulation is Transcutaneous Electrical Nerve Stimulation (TENS) units. Pads are applied to the skin overlying the most painful areas and a low current electrical charge is transmitted to the skin. The theory is that the electrical signals help override the pain signals. Treating chronic pain and depression from degenerative disc disease Chronic pain most often takes a psychological toll on patients. There can be a reinforcing cycle chronic pain commonly leads to depression, and patients who are depressed often have chronic pain. Therefore, both the depression and the chronic pain need to be treated before any significant progress with treatment is achieved.

10 Medications for depression The depression can be treated with medication, and there are several very effective antidepressants that can be useful. The newer antidepressant medications do not have as many side effects as many of the older antidepressants. As with everything else, exercise also can also help relieve some symptoms of depression. Depression medications and sleeping With depression and chronic pain, difficulty sleeping can complicate matters. If patients are not sleeping regularly, it makes it much more difficult to cope with the stress that chronic pain can create. Patients did not tolerate some of the older antidepressants (e.g. Amytriptiline) in doses prescribed for depression because the medication made patients so sleepy. However, these classes of anti-depressants are useful to treat sleep disorders, and when used at night in doses that are a fraction of what they were needed for treating depression, they are well tolerated by patients. These anti-depressants are not addictive and do not change a patient s sleep cycles. The most pronounced side effect is that many patients report an initial "hangover" effect that tends to recede over time. The anti-depressant medications also seem to have an anti-pain quality to them and many patients report a reduction in pain with these medications. They seem to be especially good for reducing nerve root pain (e.g. radiculopathy or neuropathy). Disability from chronic pain can be affected by depression The amount of disability a patient experiences is not always directly proportional to the amount of pain or pathology present. Other factors in our lives can significantly impact our level of disability. Patients who are most likely to have a great deal of difficulty returning to work are especially those who have lower than average socioeconomic status, heavy laborers, and patients with a low level of education, or who do not enjoy their work place. Patients may be scared to return to work since this is most likely where they were injured in the first place. Treating depression comprehensively It often takes a very comprehensive approach to assist patients in returning to their former level of functioning, with a team that consists of a rehabilitation specialist (physiatrist), physical therapist, psychologist, occupational therapist, and a nurse case manager who helps coordinate the care needed to treat depression and chronic pain. Ahmet Dervish MD Feb. 2006