Superior Displacement of the Dens in a Patient With Rheumatoid Arthritis
Ultimately, her disease resulted in subluxation and deformation of the knees, hands, and feet bilaterally (Fig. A and B). Her history of cervical instability warranted a magnetic resonance imaging, which showed severe central canal stenosis at the C1–C2 level, as well as impaction of C1 and C2 with the dens extending into the craniocervical junction above the level of the C1 arch and a predental space of 10 mm (Fig. C, white arrow). The patient was recommended for surgery.
This level of vertical displacement of the dens is an exceedingly rare presentation of cervical instability in the setting of RA in the methotrexate and biologic era.1 Before the advent of methotrexate and biologics, superior migration of the dens had a reported prevalence of 3% to 4% of the overall RA population.2 The predental space in normal adults is most often less than 3 mm.3,4 Predictive risk factors for cervical instability with neurological involvement in RA patients include mutilating changes and long-term corticosteroid use.5 In the era of disease-modifying antirheumatic drug therapy and biologics, these findings can be seen in patients who have lost the treatment “window of opportunity.