Crowned Dens Syndrome associated with rheumatoid arthritis: A case report of two patients with a systematic literature review.

Background: This study reported two cases of crowned dens syndrome (CDS) occurring in rheumatoid arthritis (RA) patients, along with a systematic literature review of similar cases, aiming to explore the association between RA and CDS within the context of calcium pyrophosphate deposition disease (CPPD disease). Methods: A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We performed an online systematic literature search using the PICO (Patient, Intervention, Comparison, Outcome) strategy, to identify articles reporting the association between RA and CDS. A total of five studies were included in the systematic review. Results: Most cases involved older adults aged between 60 and 80 years old. A marked predominance of female cases was observed in most cases. Clinical presentation typically included chronic or acute neck pain, stiffness, and headache. In all the studied cases, no neurological complications were reported. Standard radiographs identified atlanto-axial instability in two cases. CT imaging included calcifications of the transverse, alar, and apical ligaments encircling the odontoid process, as seen in most cases. CT might also reveal erosions, pseudotumors, or structural abnormalities. Management strategies combined colchicine, nonsteroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids, resulting in significant clinical and biological improvement. Conclusion: CDS is an uncommon condition that should be more frequently considered in patients with RA presenting with neck pain, headache, and fever. Further research studies are required to elucidate potential shared pathophysiological features between RA and CDS and to explore common treatment options.