The purpose of this study was to determine the incidence, age distribution and gender of subjects with the calcifications around the dens, and to reveal the clinical, biochemical and radiological characteristics for crowned dens syndrome (CDS). Methods: We retrospectively picked up the subjects with the calcification around the dens among patients who had undergone head and neck computed tomography (CT) between October 1, 2011 and March 31, 2012, and investigated age and gender of selected

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... cts. We also studied age, gender, clinical symptoms, body temperature, Creactive protein (CRP) levels, treatment and clinical course in patients who were diagnosed as having CDS. Results: We detected 1,056 subjects who had undergone head and neck CT, and excluded subjects who had undergone repeated CT, and also excluded patients whose CT did not show odontoid process. Three hundred sixty-five subjects were eligible for the analysis. In all subjects, age in subjects with the calcifications around the dens was significantly higher than subjects without the calcifications around the dens. In subjects who were over 65 years old, age in subjects with the calcifications around the dens was also significantly higher than subjects without the calcifications around the dens. Twenty-one (5.8%) of 365 subjects showed the calcifications around the dens. We found the calcifications around the dens in 9.6% of subjects who were over 65 years old. In the analysis of characteristics of CDS patients, we found that all patients presented neck pain, restricted neck rotation, fever, elevated CRP levels, the calcification around the dens detected by CT, and the prompt response to steroid and/or non-steroidal antiinflammatory drugs. Conclusion: To our knowledge, our study is the first to show the frequency of the calcification around the dens in the elderly people, and also a significant association between the calcification around the dens and aging. Clinical, biochemical and radiological characteristics for CDS obtained from our study help many physicians make the diagnosis of CDS.