Question: Describe crowned dens syndrome.

Context:
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. 
BACKGROUND CONTEXT: Crowned dens syndrome (CDS) is a rare form of calcium phosphate crystal depositions and often presents with recurrent neck pain, stiffness of neck, increased erythrocyte sedimentation rate, and episodes of fever.
A CT scan revealed calcification of the transverse ligament and crown-like calcification around the odontoid process. According to the clinical and radiological findings, she was diagnosed with crowned dens syndrome (CDS).
Crystal deposition in the cervical spine around the odontoid process may lead to acute neck pain. This rare condition is called crowned dens syndrome and should be considered in the differential diagnosis of a possible etiology for fever, headache and cervical pain of unknown origin. 
Crowned dens syndrome (CDS), related to microcrystalline deposition in the periodontoid process, is the main cause of acute or chronic cervical pain.
Axial calcium pyrophosphate dihydrate deposition disease (CPDD) is well known for cervical spine involvement with the crowned dens syndrome but other localisations are probably underdiagnosed in sterile spondylodiscitis. 
We describe a patient with crowned dens syndrome which manifested with clinical (acute occipital headache) and radiographic (calcium deposits in the alar ligament) features.
FDG uptake in the immediate vicinity of the odontoid process, with a crownlike calcification, was identified on the CT scan on the posterior side of the dens, thus confirming the diagnosis of crowned dens syndrome.
We describe a patient with crowned dens syndrome which manifested with clinical (acute occipital headache) and radiographic (calcium deposits in the alar ligament) features
Crowned dens syndrome (CDS), related to microcrystalline deposition in the periodontoid process, is the main cause of acute or chronic cervical pain.This report describes the case of an 87-year-old woman who had severe bradykinesia, muscle rigidity, gait disturbance and neck pain
The crowned dens syndrome, related to microcrystalline deposition in the peri-odontoid articular and abarticular structures, is mainly responsible for acute or chronic cervical pain.We report eight cases of crowned dens syndrome with atypical presentations mimicking giant cell arteritis, polymyalgia rheumatica, meningitis or discitis
The crowned dens syndrome as a cause of neck pain: clinical and computed tomography study in patients with calcium pyrophosphate dihydrate deposition disease
Computed tomography of the cervical spine demonstrated linear calcific deposits in the transverse ligament of atlas (crowned dens syndrome) in all patients.
Crystals located in the transverse ligament of the atlas give rise to the crowned dens syndrome, usually in patients affected by severe degenerative lesions of the atlantoaxial joint and peripheral chondrocalcinosis.
BACKGROUND: Patients with crowned dens syndrome typically present with severe neck pain and have calcium deposits around the odontoid process of the axis on radiographs.
We describe a patient with crowned dens syndrome which manifested with clinical (acute occipital headache) and radiographic (calcium deposits in the alar ligament) features.

Answer: Crowned dens syndrome is a rare form of "crown-like" calcifications around the dens and often presents with recurrent neck pain, stiffness of neck, increased erythrocyte sedimentation rate, and episodes of fever.