dsMRI is a modified form of the normal imaging technique, first introduced in the 1980s. This form of dynamic MRI imaging can be carried out in the same, standard, MRI machines we use now. Images are still taken with the patient lying down in the scanner (‘supine’), but rather than just take one series of images, the spine is imaged through a range of different neck positions (‘dynamic’), so its effect on the spinal cord can be seen. The major drawer back for patients is the imaging takes even longer (the researchers in this article estimate this would be an additional 15 minutes) and holding the different neck positions may not be possible for patients, as it could exacerbate their symptoms.
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In this article, the researchers found thirteen previous studies comparing dsMRI to traditional MRI techniques in the diagnosis of CSM. They found that on average, dsMRI was able to identify compression that was either missed or underestimated by traditional techniques in around 20% of patients. This suggests that dsMRI may be able to measure spinal cord compression with a higher degree of sensitivity.
It should be noted that the types of studies conducted so far are at risk of bias which means that the conclusions of this study can only be hesitant. Nevertheless, these findings are interesting as they have identified clear examples of where a standard MRI may not identify any compression, yet dsMRI does. And of course, many doctors rely on ‘MRI compression’ to make their diagnosis.
Additionally given ‘basic’ MRI imaging has been shown to poorly predict the severity of CSM and therefore response to surgery, could dsMRI change this and better inform patients?
One thing is certain, more investigation is required!
(1) Nanfung Xu et al. Does Dynamic Supine Magnetic Resonance Imaging Improve the Diagnostic Accuracy of Cervical Spondylotic Myelopathy? A Review of the Current Evidence, World Neurosurgery http://dx.doi.org/10.1016/j.wneu.2017.01.047.
By looking at MRI scans, the team were able to identify a larger amount of fatty tissue in two neck muscles, directly above and below the point of spinal cord compression. A larger build-up of fat cells was found to be linked to heightened symptoms of CSM, such as taking longer to walk 30m, and more difficulty with movement. They also found that patients with unevenness in one of their other neck muscles reported greater neck pain, and associated problems.
The increase of fat cells in muscle can be linked to a number of causes, but is most often seen as a normal part of the ageing process. Previous research has already found that we can reduce this age-related build-up of fat using physical activity and regular exercise (2), so the Canadian team speculate that a scheme of targeted neck exercises might help to improve the results of surgery in the treatment of CSM.
It’s important to remember however, that this research is still in its early days, and that so far, and a number of questions remain unanswered:
- Can neck exercises reverse fat infiltration?
- if so, what type of exercises are appropriate?
- Does this improve patient symptoms?
- Is it a consequence of CSM, or related to its origins?
It should be remembered that neck exercises will not remove the compression behind CSM and that at present, this can only be treated with surgery. Additionally some suggest extensive neck therapy before surgical treatment can make symptoms worse. (3) More work will need to be done to see whether the possible benefits of exercise are actually seen in patients, and if so, which types of exercises are most useful. However, if the suggestions made in this paper are found to be accurate, then this could be a simple way for patients to change the way that they prepare for surgery, in order to improve results.
(1) Fortin M, Dobrescu O, Courtemanche M, Sparrey CJ, Santaguida C, Fehlings MG,Weber MH. Association Between Paraspinal Muscle Morphology, Clinical Symptoms and Functional Status in Patients With Degenerative Cervical Myelopathy. Spine (PhilaPa 1976). 2016 May 23
(2) Hamrick, Mark W., Meghan E. McGee-Lawrence, and Danielle M. Frechette. “Fatty Infiltration of Skeletal Muscle: Mechanisms and Comparisons with Bone Marrow Adiposity.” Frontiers in Endocrinology 7 (2016): 69. PMC. Web. 15 Feb. 2017
(3) Rhee JM, Shamji MF, Erwin MW, Bransford RJ, Yoon T, Smith JS, Kim HJ, Ely CG, Dettori JR, Patel AA, Kalsi-Ryan S. Nonoperative management of cervical myelopathy: a systematic review. Spine
It has been well shown in many studies that Cervical Spondylotic Myelopathy (CSM) is a chronic and debilitating condition that reduces quality of life (1). However, until recently no one has studied how this compares to other common chronic conditions.
The study also found that the mental impairment caused by CSM was worse than for any of the other conditions, surpassed only by back pain and sciatica.
This was a well conducted, large, multi-centre study which successfully demonstrated that CSM carries a greater physical and mental disease burden than many other conditions, including cancer, diabetes and chronic lung disease. With a growing elderly population causing the prevalence of CSM to rise (3), the average age of a CSM patient is 57 (2), this study has made the important point that the condition is affecting an increasing number of people and to a greater extent than many better known diseases.
With this in mind, it is only fair to say that CSM deserves to receive a far larger share of medical attention than it does at present.
1. Al-Tamimi YZ, Guilfoyle M, Seeley H, Laing RJ. Measurement of long-term outcome in patients with cervical spondylotic myelopathy treated surgically. Eur Spine J . 2013 Nov;22(11):2552–7.
2. Oh T, Lafage R, Lafage V, Protopsaltis T, Challier V, Shaffrey C, et al. Comparing Quality of Life in Cervical Spondylotic Myelopathy with Other Chronic Debilitating Diseases Using the SF-36 Survey. World Neurosurg. 2017 Jan 5;
3. Wang MC, Kreuter W, Wolfla CE, Maiman DJ, Deyo RA. Trends and variations in cervical spine surgery in the United States: Medicare beneficiaries, 1992 to 2005. Spine. 2009 Apr 20;34(9):955-961-963.
We are often asked whether you should wear a neck collar after surgery for CSM. Some centres advise it and some do not.
This is a well conducted study, which shows very clearly that the collar offers no benefit on symptoms or recovery after surgery. It reiterates the same message discussion during the Myelopathy.org Patient Information Day.
So if there is no difference, should I wear a collar or not? This will need to be discussed with your surgeon. Whilst there is no benefit in terms of symptoms or recovery, some types of operation for CSM may require a period of stabilisation with a collar. It should be remembered that this study was done in patients undergoing cervical laminoplasty without instrumentation (metal fixation).
1. T.Hida et al. Collar Fixation is not Mandatory after Cervical Laminoplasty: A Randomized Controlled Trial Spine Nov 2016
2. Mark Kotter at the Myelopathy.org Patient Information Day
"The dogma that the central nervous system cannot regenerate is simply not true; we just haven’t figured out how to make it happen yet."
These neurons, and their connections to the spinal cord, do not regenerate. To regenerate specific neurons, we must understand how they are generated in the first place. In other words, we believe that the key to achieving therapeutic regeneration is a clear understanding of development.
How genes are regulated to control corticospinal motor neuron development is just beginning to be understood. One way genes are regulated is by small, non-coding RNAs (microRNAs). Our lab has recently discovered that microRNAs appear to be critical to corticospinal motor neuron development. The members of my lab are investigating the ability of microRNAs to control corticospinal motor neuron development in the embryo, in immature brain cells in the dish, and in stem cells.
Why is this exciting?
Regulation by microRNAs represents an entirely new way of understanding the generation of these important neurons. If we can understand how neurons naturally develop, we will be able to identify targets to stimulate their regeneration.
1) Tharin Lab, University of Stanford
2) S.Tharin et al A microfluidic device to investigate axon targeting by limited numbers of purified cortical projection neuron subtypes. Integr Biol (Camb) Nov 2012
3) Iyer et al. Cervical Spondylotic Myelopathy. Clin Spine Surg. Jun 2016
This group followed up 135 patients with CSM, of which some patients underwent surgery and some did not. They found that the blood pressure of patients undergoing surgery improved (lowered) after surgery, whereas those who did not, remained the same.
You of course might say, well 'stress and pain' are a result of CSM, surely if they improve after surgery, my blood pressure will go down? Well the group measured pain, and found that the improvement of blood pressure did not relate to pain, but instead severity of CSM...
This puts the cat amongst the pigeons. Why should CSM cause high blood pressure?
That remains an unanswered question. This study did not measure stress, additionally some limitations in the study, particularly the number of patients, may have hidden a relationship with pain.
However there is some theory to the idea that CSM could affect your blood pressure. Control of blood pressure is naturally dependent on many things. Partly it relies on some very small nerve fibres called your 'Sympathetic Nervous System'. Although this nervous system is separate to your spinal cord, there is some communication which could be potentially disrupted in CSM. If we look at patients who have a traumatic spinal cord injury, their blood pressure is often unstable as a result. So there could be something more to this than simply pain or stress! We will have to watch this space! But be prepared to reduce your blood pressure medication after surgery if that is applicable.
What were the researchers looking at and why?
The researchers were investigating the use of a drug called Cilostazol in cervical spondylotic myelopathy (CSM). This drug has been shown to be a safe and effective drug in humans, which can reduce nerve cell damage. The group therefore wanted to test whether this drug can protect nerve cells in CSM.
What did this study show?
Rats with CSM had reduced running ability on a treadmill and reduced grip strength. There was also increased loss of nerve cells. Rats that received the drug Cilostazol had preserved grip strength and running ability. Cilostazol also prevented nerve cell loss.
Cilostazol is a drug, which inhibits the enzyme phosphodiesterase (PDE). PDE normally breaks down a molecule called cyclic adenosine monophosphate (cAMP). cAMP is involved in relaxation of the blood vessels. Cilostazol therefore increases levels of cAMP and causes relaxation of the blood vessels. Cilostazol may therefore improve function in CSM by widening the blood vessels and improving blood flow (Figure 1).
Cilostazol appears to improve function in CSM, however its' mechanism of action in CSM needs to be studied. In particular, its effect on blood flow and whether it does indeed cause widening of the arteries or has other affects must be investigated.
What does this mean for patients with CSM?
As Cilostazol is licensed for use in humans, this drug has huge potential for use in CSM. Its exact mechanism of action and potential side effects in CSM need to be tested.
Yamamoto S, Kurokawa R, Kim P. Cilostazol, a selective Type III phosphodiesterase inhibitor: prevention of cervical myelopathy in a rat chronic compression model Laboratory investigation. J Neurosurg Spine. 2014. 20 (1):93-101.
Proposed mechanism of action of Cilostazol.
This has changed with a study from North America.  They reconfirmed the finding that smokers do not recover as much as non smokers after surgery, but went on to show that this is related to how much you smoke. I.e. The more you smoke, on average, the less you recovery after surgery, currently the only treatment for CSM.
Speaking at the 31st Annual Meeting of the North American Spine Society, David Kusin the lead author suggested smoking limits the natural healing process. The exact way in which smoking impairs recovery is unclear. Some experts believe the affect is due to hardening of the arteries (accelerated by smoking and responsible for conditions such as heart attacks). Their theory is that once the compression is removed, and blood flow returns to support the healing process, in smokers the is less effective.
What ever the exact mechanism, the impact is clear. Smoking is harmful and smoking is something you can change.
1. Kusin et al. The effect of smoking on Spinal Cord Healing following surgical treatment of cervical myelopathy. Spine June 2015
We are committed to raising awareness of CSM. We have been working with Cambridge TV to produce a documentary about the condition. This includes interviews from patients at the September CSM day, hosted at the University of Cambridge. Part 1 aired a few weeks ago, but now Part 2 is ready for viewing. Thanks to all at Cambridge TV for putting together this excellent summary of the disease, its impact and the future of treatment. Hope you enjoy. Let us know what you think!
As we have been reiterating throughout this blog, CSM is massively under-recognised. We are working to raise the profile of the disease, and have been very grateful for the support of Cambridge TV who have made a 2-part documentary about the disease. See part 1 here. This includes interviews of patients and their supporters from our CSM Day at the University of Cambridge
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