Crowned Dens Syndrome: Report of Three Cases and a Review of the Literature.

Background: Patients with crowned dens syndrome (CDS), which is pseudogout of the atlantoaxial junction induced by "crown-like" calcifications around the dens, present with symptoms of severe neck pain, rigidity, and high fever. CDS patients are often misdiagnosed as having meningitis or polymyalgia rheumatica, leading to potentially unnecessary invasive procedures for diagnosis and treatment.

Methods: We report 3 patients with CDS who had characteristic findings on computed tomography (CT), all of whom quickly recovered with nonsteroidal antiinflammatory drug (NSAID) administration. In addition, we reviewed 72 published cases, including our patients. CDS typically occurs in elderly people (mean age 71.4 years). Common symptoms include neck pain (100%), neck rigidity (98%), and fever (80.4%), and most show elevated inflammatory markers (88.3%) on serum laboratory tests. Neck pain on rotation is a characteristic and helpful symptom in the diagnosis. The most useful modality is CT (97.1%), showing linear calcium deposits around the dens, mostly in the transverse ligament of atlas (TLA). CT number is especially helpful to distinguish a normal TLA (35-110 HU) from a calcified one (202-258 HU) in our cases. The most effective treatment is NSAID administration (85%), which usually leads to marked resolution of symptoms within days or weeks. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Due to acute and severe symptoms, CDS patients often present to an emergency department. To avoid unnecessary invasive procedures for diagnosis and treatment, CDS should be considered in the differential diagnosis of febrile neck pain.