Crowned dens syndrome: a rare cause of acute neck pain.

Crowned dens syndrome (CDS) is a rare but underrecognized cause of severe neck pain in older adults. It is characterized by acute onset pain and stiffness of the cervical spine. Accompanying fever and elevated inflammatory markers often lead to misdiagnosis. It is frequently associated with calcium pyrophosphate deposition disease, hydroxyapatite crystals, and sometimes other inflammatory conditions. Periodontoid calcification is seen on cervical computed tomography (CT) scan but is not typically visible on plain radiographs, making CT scanning invaluable in diagnosis. We describe a case of CDS in a 59-year-old woman, who presented with severe neck pain, elevated inflammatory markers, and progressive evolution in the appearance of her CT scans. The pathophysiology, clinical and radiographic findings, and dramatic response to corticosteroid therapy are reviewed.