E-mail: moc. This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4. A bstract External occipital protuberance is normal anatomical entity, rarely it may show hyperostosis and may get prominent and causing pain and examination reveals presence of tender bony swelling.
K eywords: Hornlike curved external occipital protuberance , management , pain , surgical intervention. Open in a separate window. Figure 1. Figure 2. X-ray of skull lateral view showing downward pointing external occipital tubercle. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms.
Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. R eferences 1. Bogduk N. The anatomy of occipital neuralgia. Case with hidden diagnosis. Full screen case with hidden diagnosis.
Presentation The mass sensation at occiput region. Patient Data Age: 15 years. From the case: Prominent external occipital protuberance. Loading images Loading Stack - 0 images remaining. Case Discussion External occipital protuberance is a midline bony prominence in the occipital bone that ligamentum nuchae and trapezius muscle attach to its tip.
Exaggerated external occipital protuberance also is known as an occipital spur. Cris Hernandez. Related Radiopaedia articles. Inion Occipital spur. Promoted articles advertising. Outlying points were included in the analysis. In men with EOP enlargement, the mean volume was 2. In women with EOP enlargement, the mean volume was 1. This value corresponds to the 85 th percentile of the dataset for young women with EOP enlargement. CT analysis of a young female Egyptian mummy.
Panel b. Panel c. This value corresponds to the 73 rd percentile of the dataset for young men with EOP enlargement. Though no direct relationship can be established, this major increase contrasts with the stability of the rate and volume of EOP enlargement during the same time period. Evolution between and of the ownership of smartphones at a national scale adapted from The impact of modern life on EOP changes in millennials has been the subject of recent publications 4 , 10 , However, these publications relied on data from conventional X-ray examinations and did not provide several time points, to better understand the evolution of EOP measurements over time.
Actually, the medical literature regarding EOP size remains poor, and no volumetric data were ever published on this topic so far. Thus, a dedicated scientific study with a more precise evaluation of EOP size and shape, and including data from different times seemed necessary. On a population scale, our study shows that EOP enlargement is a frequent finding in millennials , and was already present at the very beginning of the smartphone era, without significant differences in prevalence or size as compared to today, which is not in favor of a rapidly changing environmental factor during this period.
This imaging modality is more sensitive than conventional radiography for the depiction of changes in the bone. This highly accurate assessment might have led to an overestimation on prevalence and size of EOP as compared to radiographic or morphologic studies. It has also been reported 16 that male individuals have higher occipital bone thickness around the EOP.
The use of imaging techniques could thus be overestimating the prevalence of EOP enlargement compared to morphological studies, partly because it is sometimes difficult to differentiate the deep part of the EOP from a focal enlargement of the occipital bone.
There is no consensus on the definition of an enlarged EOP. Previous studies 4 , 7 , 10 relied on only one or two linear measurements to define EOP enlargement.
However, this approach does not take the shape of the EOP into account, which can be highly variable between individuals. To overcome this issue, we decided to measure EOP volume instead, because it enabled a more precise and suitable delineation of the EOP. This study focused on a limited time 8 years and cannot rule out a more progressive impact of other environmental factors from older decades on EOP size in the general population.
However, this study also shows, through two older examples, that EOP enlargement was already present in young individuals from ancient populations. This study only shows two of these examples and cannot rule out, however, that the results would have been different on a larger population of ancient skulls and that the evolution of EOP over time follows a slowly progressive path. Precise assessment of the changes in EOP over longer periods of time, with adjustment towards confounding factors that might change neck constraints e.
On an individual scale, it is noticeable that few cases from both and datasets were clear outliers Fig. It would be interesting to focus individually on patients with this kind of EOP to look for innate or environmental factors that could have led to this condition. One study 11 reported that inflammatory or genetic factors did not seem to be involved in EOP enlargement, but it relied on a small number of patients. It would be interesting to undertake such a study on a larger scale, especially in symptomatic patients.
We acknowledge several limitations in our study. Firstly, it was a retrospective study performed at a single institution university hospital. Studies performed in different hospitals with different CT indications or in different countries might show different results. Nevertheless, we believe our methodology favored a comparison between homogenous populations. Secondly, since the work was performed retrospectively on anonymized CT datasets, it was not possible to assess directly the individual use of smartphones of patients.
The data we used were derived from national official data on this topic, and give an overall glimpse of the use of smartphones. However, while interesting, they represent only one environmental parameter, among many potential confounding factors. Though the impact of rapidly growing modern environmental factors - such as smartphones - on EOP changes seems unlikely given the stability of EOP size in the last decade, the design of our study does not allow thorough correlation with risk factors.
Thus, further studies with a robust design enabling an adjustment of EOP size with confounding factors are needed to draw more robust conclusions on the impact of environment on EOP changes.
Thirdly, since the datasets were retrospective and anonymized, we could not establish a correlation between the size of the EOP and potential cervical symptoms. However, the datasets were derived from head CT performed in the Emergency Radiology Department of our institution, for which the main imaging indications are related to an acute event head trauma, acute headache or acute neurological symptom for example , and without a priori specific reasons to suffer from cervical symptoms more than the general population.
The choice to work on head CT examinations rather than cervical spine CT examinations was driven partly by this reason, because the dataset could have been biased in the latter, with an over-representation of patient with cervical symptoms that could have altered the generalization of our description.
Finally, one can argue that is not far enough to draw conclusions on the evolution of EOP over a longer period of time. This study specifically focuses on millennials aged and the potential rapidly evolving impact on modern life on this population, since they were the principal age group for whom concerns were raised Going further back in time would have led to the inclusion of patient from previous generation X, who underwent different life events and environmental constraints Moreover, the number of confounding factors resulting in ossification of the entheses mechanical, inflammatory, metabolic… increases with age Since our design did not enable a robust adjustment for confounding factors, the addition of older patients could have introduced a significant bias.
These findings suggest that EOP enlargement was already present and frequent at the beginning of the last decade, and probably even long before. This makes the impact of rapidly growing modern environmental factors - such as smartphones - on EOP changes unlikely. Kadri, P. Anatomy of the nuchal ligament and its surgical applications. Neurosurgery 61 , —; discussion The external occipital protuberance: can it be used as a criterion in the determination of sex?
Forensic Sci. Article Google Scholar. Marshall, R. Painful exostosis of the external occipital protuberance. J Plast Reconstr Aesthet Surg 68 , e— Shahar, D. A morphological adaptation? The prevalence of enlarged external occipital protuberance in young adults. Varghese, E. Occipital spur: understanding a normal yet symptomatic variant from orthodontic diagnostic lateral cephalogram.
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