Prevalence and Underreporting of Crowned Dens Syndrome-Associated Calcifications on Cervical Spine CT in Patients with Neck Pain.

Background: Crowned dens syndrome (CDS) is characterized by acute neck pain and restricted motion due to calcium pyrophosphate (CPP) crystal deposition around the atlantoaxial joint. Although recognized as sufficient for the diagnosis of CPP deposition disease (CPPD), its prevalence remains uncertain. Given the high prevalence of CPPD in the general population, CDS may be more common than currently appreciated among patients with neck pain undergoing cervical spine imaging. Methods: This retrospective study included patients aged ≥40 years who underwent cervical spine CT for evaluation of neck pain between 2022 and 2024. Of 500 consecutive scans, 195 were eligible after excluding trauma-related, post-operative, and metastatic cases. Results: Periodontoid calcifications were identified in 29.2% of patients (mean age 61.5 ± 11.7 years; 37.4% male). Prevalence increased significantly with age (p < 0.001), reaching nearly 50% in those over 70 years. Linear calcifications were rare before 60 years (1.2%) but present in 24.5% of patients over 70. Calcifications were mentioned in only 3.5% of radiology reports. Conclusions: Periodontoid calcifications are relatively common in patients with neck pain, affecting nearly one-third of individuals over 40 and almost half of those over 70. Their frequent underreporting highlights a critical gap in recognition. Greater awareness and systematic reporting are warranted, as CDS may represent a common, underdiagnosed, and treatable cause of neck pain.