Background Crowned dens syndrome (CDS) is a clinical and radiographic entity characterized by acute neck pain, positive inflammatory indicators and periodontoid calcification by a cervical CT scan.[1,2] However, these features can be seen in other diseases such as giant cell arteritis, meningitis, rheumatoid arthritis, or subarachnoid hemorrhage. Therefore clinical suspicion and evaluation of CDS are important when examining patients with undiagnosed acute neck pain or headache.

Objectives To investigate the diagnostic utility of chondrocalcinosis in knee X ray to diagnose CDS.

Methods This study is a retrospective cohort study. The subjects were the patients with suspected CDS who underwent a cervical CT scan in our hospital between 8/1/2009 and 3/31/2013. Among them, we compared patients' characteristics. All patients with suspected CDS must have undiagnosed acute neck pain or headache. CDS is diagnosed if all of the following were met: acute neck pain or headache, positive inflammatory indicators (WBC>9000/μl; CRP >0.3 mg/dl, ESR>15mm/hr), presence of periodontoid calcification by cervical CT scan, and exclusion of other diseases. Two blinded radiologists reviewed the radiographs and gave consensus reading to rheumatologists. Two rheumatologists independently reviewed clinical information obtained from electric records and the radiologists' reading of the cervical CT scans and the knee x rays and made final diagnosis. Clinical parameters were compared between the group of patients diagnosed with CDS (CDS group) and the group of patients finally diagnosed with non-CDS (Non-CDS group).

Results Of the 2240 patients who underwent a CT scan evaluating the cervical spine between August 1, 2009 and March 31, 67 patients underwent cervical CT scan for suspicious CDS. Among them, 36 had acute neck pain or headache with suspect of pseudogout attack, 27 had acute neck pain or headache with positive inflammation markers, and 4 had acute neck pain or headache only. One patient was excluded because of the dental artifact in the CT. Thirty-four patients were finally diagnosed with CDS. The final diagnosis of the 32 patients who were not diagnosed with CDS was as follows: rheumatoid arthritis (6), polymyalgia rheumatica (5), cervical spondylosis (4), giant cell arteritis (2), tumor metastasis to the cervical spine (1), osteomyelitis (1), ankylosing spondylitis (1), Calcific tendinitis of the longus colli (1), tension headache (1), neck spasm (1), and unknown (9).Table 1 shows clinical features of the CDS group and the Non-CDS group. Significant differences were observed with respect to age, recurrent neck pain, and chondrocalcinosis. Sensitivity and specificity of knee chodrocalcinosis were 64.3 (53.4-69.5) % and 89.5 (73.4-96.9)%. Multiple logistic regression analysis showed knee chondrocalcinosis is the single strongest predictor (AOR 16.7, p<0.001).

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Conclusions When CDS is suspected, chondrocalcinosis in plain knee X ray is helpful for clinical diagnosis of CDS.

References

1. Bouvet JP, le Parc JM, Michalski B, Benlahrache C, Anquier L. Acute neck pain due to calcifications surrounding the odontoid process: the crowned dens syndrome. Arthritis Rheum. 1985;28:1417-20.

2. Goto S, Umehara J, Aizawa T, Kokubo S. Crowned Dens Syndrome. J Bone Joint Surg Am. 2007;89:2732-6

Acknowledgements Dr. Yokogawa and Dr. Seki contributed equally to this study.

Disclosure of Interest None declared

DOI 10.1136/annrheumdis-2014-eular.5587