Risk of acute coronary syndrome in patients with cervical spondylosis
J.Hamilton
Various studies in the past have described cervical spondylosis (CS), the degenerative changes in the cervical bones and ligaments contributing to degenerative cervical myelopathy, as associated with increased sympathetic nervous tone[1][2].
The sympathetic nervous system plays a role in controlling blood pressure, heart rate and various other aspects of our cardiovascular health. But part of its control structure also lies in close proximity to the cervical spine.
Increased sympathetic activity is known to contribute to increased atherosclerosis and cardiovascular events such as stroke, and myocardial infarction (heart attack)[3].
The authors noted that no research had been done to link the above statements, if CS does cause increased sympathetic activity, does this logically follow that CS causes an increased incidence of cardiovascular events?
With this in mind, the aim of the study was to determine if cervical spondylosis increased the risk of cardiovascular health issues, specifically acute coronary syndrome (ACS), which in common terms is a heart attack.
Picture
The sympathetic nervous system is involved in controlling many of your bodies organ systems. Signals originate from 'ganlgion' that lie adjacent to the spine. The ganlgion in the cervical spine are involved in control of the cardiovascular system
How was the study performed?
The authors used a national insurance claims dataset of 22 million people in Taiwan and identified 27,947 patients with CS, they then matched this with a similar number of non-CS patients of a similar age and gender distribution, as well as matching numbers of patients with other health problems such as hypertension, diabetes, asthma and stroke. This was to allow them to compare the incidence of ACS between the groups without other diseases invalidating the comparison.
All the patients were followed up until they had a diagnosis of ACS, died, or the end of the research period occurred at the end of 2011. After this, the number of ACS events in each group were measured as a rate over the number of “person years”. This being the number of times a diagnosis of ACS was made for every year a patient lived.
In this paper, the incidence of ACS was measured as number of ACS/1000-person years. These were then compared between various groups to obtain a ratio, to determine the relative risk of ACS occurring in a person with CS compared to someone without ACS in a similar state of health.
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What were the main findings?
Overall, the study showed that patients with CS were 13% more likely to have an ACS, than patients without CS. This was determined 'statistically significant', but in real terms this represents a very small increase from 3.9/1000-person years to 4.27/1000-person years in rates of ACS diagnosis.
Looking in more detail at the patients with CS, for those with myelopathy the risk was slightly higher, increasing by 20% but interestingly, it seems treatment of CS has an effect in reducing ACS risk:
- Patients receiving spinal decompression surgery were less likely to have an ACS (27% reduction)
- Patients receiving rehabilitative therapy were less likely to have an ACS (33% reduction)
The statistical difference between the form of treatment for CS and reducing ACS risk was not significant.
How could cervical spondylosis cause acute coronary syndrome?
This is a good question, and not entirely clear. The researchers suggested that it may be to do with the sympathetic trunk. The cervical sympathetic trunk consists of collections of nerve cells bodies, called ganglia, aligned along the front of the spine. The ganglion in the neck are involved in control of the cardiovascular system. This special group of nerves also connect with the ligaments of the spinal column, such as the posterior longitudinal ligament, and the lining of the spinal cord. Irritation to these structures is thought to cause the sympathetic nervous system to increase its output, for example to fibers in blood vessels around the body, causing them to constrict and causing hypertension, which contributes to a diagnosis of ACS.
What can we take from this study?
This is not the first study to show a relationship between CSM and Cardiovascular health (we have previously described a study specifically looking at high blood pressure), however it is the first to show an increased risk of a heart attack.
There are a number of limitations to this study, and the actually increases in risk are relatively small. But it adds to the research of CSM and Cardiovascular disease, and once again shows the far reaching impacts of CSM.
References
Shih-Yi Lin et al. Risk of acute coronary syndrome in patients with cervical spondylosis Atherosclerosis 2018
[1]M. Singh, I. Khurana, Z. Kundu, A. Aggarwal, Link of sympathetic activity with cardiovascular risk in patients of cervical spondylosis, Int. J. Clin. Exp. Pathol. 3 (2016) 41e44
[2]M. Singh, I. Khurana, Z.S. Kundu, A. Aggarwal, Galvanic skin response in pa- tients with cervical spondylosis, IJHSR 6 (2016) 148e152.
[3] N. Marina, A.G. Teschemacher, S. Kasparov, A.V. Gourine, Glia, sympathetic activity and cardiovascular disease, Exp. Physiol. 101 (2016) 565e576,
