Crowned dens syndrome

Dear Editor, A 90-year-old man visited our emergency department owing to neck pain and occipital headache. The pain occurred suddenly a few days previous, and had become gradually worse. He had a history of cerebral infarction, dementia, and cholelithiasis, but was not on any medication. The patient’s vital signs were stable excluding a body temperature of 37.5°C. Physical examination showed the reduction of passive cervical spine movements with posterior neck pain and occipital headache. Rotation, extension, and flexion in the neck were all limited. However, there was no tenderness in the nape of the neck. In terms of neurological findings, overall cranial nerve, motor, and sensory nervous systems were intact. In laboratory data, the value of the C-responsive protein was 4.34 mg/dL (normal range, 0.0–0.1 mg/dL); all other findings were unremarkable. Computed tomography (CT) of the neck showed crown-shaped calcium deposits surrounding the odontoid process (Fig. 1A, arrows), and dotted calcifications of the transverse ligament of the atlas (Fig. 1B, arrows).There were no other lesions causative of pain in brain or spine. By integrating the results, we diagnosed crowned dens syndrome (CDS). The chief complaint of patients of CDS is neck pain, due to calcification deposition around the odontoid process. The cause of CDS is thought to be the microcrystalline deposition, most often calcium pyrophosphate dihydrate crystals and/or hydroxyapatite crystals, in the transverse ligament of the atlas around the odontoid process. However, the pathophysiologic process has not been completely proven. Clinicians could confuse the differential diagnosis and misdiagnose CDS as meningitis, polymyalgia rheumatica, or dissecting aneurysm of the vertebral and basilar artery. In particular, meningitis must be considered first in the differential diagnosis because the triad of fever, headache, and neck stiffness due to meningitis are very similar to the symptoms of CDS. Using CT scans, CDS is identified in up to 5% of the patients over the age of 70 years who present to hospital with the chief symptom of neck pain. Therefore, it is not a rare entity but becoming unclear using plain radiography for the diagnosis because of improper images. Computed tomography is the gold standard for detecting calcification in transverse, apical, and alar ligaments. However, when the CT scan is carried out a long time after the onset of symptoms, calcification around the odontoid process may not be detected as it may have been absorbed. Non-steroidal anti-inflammatory drugs (NSAIDs) have been commonly used as first-line therapy for CDS. In cases without improvement using NSAIDs alone, treatment with moderate dosage of corticosteroids is recommended. In our case, NSAID therapy alleviated the patient’s symptoms completely. Taiki Yamada, Takeji Saitoh, Hironao Hozumi, Yoshiaki Takahashi, Masashi Nozawa, Toshiaki Mochizuki, and Atsuto Yoshino Department of Emergency and Disaster Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan