[Acute headache and neck pain caused by crowned dens syndrome].

Background: Crowned dens syndrome (CDS) is a rare cause of acute headache and neck pain, which is accompanied by fever and a stiff neck. It is caused by calcium deposits (pseudogout) around the dens axis (C2).

Case Description: A 61-year-old woman, with a history of migraine and of breast cancer 8 years previously, was referred to the accident and emergency department of our hospital with acute headache and neck pain. She was treated in the department with prednisone, on suspicion of giant-cell arteritis. However, an 18F-FDG-PET-CT showed inflammation and calcification around the dens, consistent with CDS. The patient's condition improved rapidly after treatment with prednisone.

Conclusion: CDS should be considered in the differential diagnosis of acute headache and neck pain. Familiarity with the disease course can prevent unnecessary diagnostic tests and treatment. The syndrome can be easily diagnosed with a CT scan, but an 18F-FDG-PET-CT can also be used to reveal inflammatory activity around the dens.