The natural history of cervical spondylotic myelopathy (CSM) is the topic of this article. Natural history refers to what happens to a person with this type of problem as time goes by. Do they get better, worse, or stay the same? CSM is a degenerative condition that occurs with aging. Adults affected most often are 50 years old and older. The term myelopathy refers to any problem that affects the spinal cord. Cervical tells us the area affected is the cervical spine (neck region). Spondylotic or spondylosis describes a narrowing of the spinal canal where the spinal cord is located.
So, basically what we are describing is a narrowing of the spinal canal that puts pressure on the spinal cord and causes neck pain, arm pain, and sensory symptoms such as numbness and tingling down the arm. Sometimes there’s a shock-like feeling down the arms when the head and neck are flexed. Pressure on the spinal cord causes this sensation called Lhermitte’s sign.
There is a wide range of changes associated with aging that contribute to spondylosis that leads to symptoms of myelopathy. For one, the vertebra themselves lose height and push down on the discs and facet (spinal) joints. Pressure around the joints from rubbing together causes the vertebral body to form bone spurs that reduce motion and cause additional pain.
This kind of compression affects the spinal nerves more than the spinal cord but both can be involved directly or indirectly. As these structural changes take place, thickening, hardening, and buckling of the ligaments occur along the spine. And that is a common factor in the development of cervical spondylotic myelopathy. Anyone who has a narrow spinal canal from birth is especially susceptible to these age-related problems.
So, what is the natural history of cervical spondylotic myelopathy? Can a person outgrow it? If it comes with aging, does it get worse as we get older? If we know how a condition is going to respond over time, it’s easier to predict which types of treatment would work best and which subgroups of patients would respond to those treatment approaches.
After a thorough review of studies published with good-to-high quality of evidence, it would seem that cervical spondylotic myelopathy can go any number of ways. In some cases, there is a slow decline over time. The patient seems to get worse, plateaus (stays the same) or may get slightly better, then declines even more. This pattern is referred to as a stepwise decline. In other cases, the patient is symptom-free or perhaps experiences no change in symptoms over a long period of time.
Is there some way to predict who will progress and get worse and who will stabilize/stay the same? For that matter, is it possible to predict if anyone with this degenerative problem will get better? After all, if it is age related, we can’t reverse the effects of aging or stop the aging process.
After looking at all the articles published, the authors found 17 studies that met their criteria (i.e., to be of good enough quality to offer reliable evidence). They provide a nicely organized table to summarize key findings for each study. After listing the authors’ names and year the article was published, they wrote a short description of each one with results, level of evidence, and conclusions. Here are a few of the key points they made after reviewing all the evidence.
1) The natural history of cervical spondylotic myelopathy is mixed and somewhat unpredictable.
2) Those who have this condition get worse over time.
3) As the spondylosis (narrowing of the spinal canal) gets worse, the risk of damage and even death of the spinal cord cells increases.
3) Younger adults (less than 75 years old) seem better able to adapt and improve without surgery.
4) For those patients (of any age) who got better with nonoperative (conservative) care, they are able to maintain these good results for three
years or more.
Most of the studies don’t include patients who have severe symptoms. This leads to a bit of skew in the results. Results aren’t as poor as they might be if everyone from mild to severe were included. In other words, the results might be different if those folks labelled severe were included. The fact that the natural history of cervical spondylotic myelopathy has a mixed picture and that not all patients were included in the study alerts us to the fact that we need better studies. The authors point out the need for high-quality random controlled trials to sort this all out.
Finding subgroups who respond (or don’t respond) to treatment and finding predictive factors to help spot folks who will have one outcome (poor result/good result) over the other takes time and effort. Studies with this focus would be very helpful indeed. For now, this study has shown us that there isn’t enough evidence to answer the question of why some people get worse and others don’t, or why some people develop this problem and others do not.
The lack of understanding around the natural history of cervical spondylotic myelopathy makes it difficult to plan treatment or management programs. Knowing that patients won’t get better who have severe symptoms that have been present a long time makes it difficult to include them in clinical studies, yet there’s a need to find ways to treat these patients. The authors of this study point out this dilemma but make no suggestions as to how to deal with it.
However, they do make several helpful recommendations based on current evidence regarding cervical spondylotic myelopathy. First, younger patients with this condition should be offered all treatment options (both conservative and operative). All efforts should be made to manage symptoms early on to avoid progression. This is especially important because research shows that the positive results can last a long time. Patients should be told up front that this condition is likely to get worse over time. They should be told to expect long periods without problems followed by sudden flare-ups of worsening symptoms.
Anyone with severe symptoms is in danger of permanent spinal cord damage. And they are not likely to get better without treatment. Therefore, decompression surgery is recommended to take pressure off the spinal cord. Testing with electromyography (EMG) should be done to see if there are abnormal motor responses (slow, delayed or absent muscle contraction). This is another sign that surgery to decompress the spinal cord is needed.
That concludes the findings from this review of the natural history of cervical spondylotic myelopathy. Researchers have been alerted to the need for some quality studies in the future. Hopefully, we will see the results of those studies translated into treatment guidelines in the not-too-distant future.