PURPOSE: The purpose of this study was to verify the value of computed 
tomography (CT) in the diagnosis of the "crowned dens" syndrome, not only in 
crystal deposition diseases, but also in other rheumatic or nonrheumatic 
conditions.
MATERIALS AND METHODS: Thirty-eight patients (15 men and 23 women; mean age 55 
years; age range 35-79) with neck pain were examined and divided into two 
groups: (1) patients already identified as rheumatic and referred for further 
investigation of the atlantoaxial region; (2) patients with symptoms confined to 
the cervical spine, with inconclusive radiographic findings. Unenhanced CT of 
the cervical spine (Tomoscan SR 7000 Philips, Eindhoven, Netherlands) was 
performed in all patients. There were 11 cases of rheumatoid arthritis (ten 
women and one man), two calcium pyrophosphate dihydrate crystal deposition 
disease (both women), one of systemic sclerosis (a woman), one of osteoarthritis 
(a man), one of seronegative arthritis (a man), four of neoplasm (one woman and 
three men) with suspected cervical involvement, one (a man) of haematological 
disease (lymphoma), one (a woman) of menopausal osteoporosis, ten (five men and 
five women) of recent or previous trauma with suspected involvement of the skull 
base and first cervical vertebrae and six of unknown painful cervical 
dysfunction (three men and three women).
RESULTS: CT demonstrated calcific deposits around the dens in 12 patients (three 
men and nine women), in the transverse and alar ligaments, and in the anterior 
atlantooccipital membrane. CT revealed horseshoe- or crown-like calcification 
surrounding the odontoid process. In our series, other rheumatic diseases, 
especially rheumatoid arthritis, showed similar irregular calcifications of the 
atlantoaxial joint. Discussion. In calcium pyrophosphate dihydrate (CPPD) 
crystal deposition disease, the spine may be the only site of involvement, 
generally asymptomatic. 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. 
Symptoms may be absent, or a neurological compressive syndrome may develop. 
Symptoms tend to worsen with age. The diagnosis is not always easy, as the 
symptoms are similar to those of other diseases, such as meningitis, 
cervicobrachial pain, occipitotemporal headache, calcific tendinitis of the 
longus colli muscle, spondylodiscitis and retropharyngeal abscess.
CONCLUSION: CT is the gold standard in identifying crowned dens syndrome, as it 
is able to depict the shape and site of calcification and any bone erosions. 
Radiography of other joints (wrist, knee, pubic symphysis) may help to ascertain 
whether the disease is due to calcium pyrophosphate dihydrate or hydroxyapatite 
crystals, and is therefore recommended for routine patient management. Magnetic 
resonance imaging (MRI) is indicated for the study of neurological 
complications.