Symptomatic cervical synovial cyst associated with an Os odontoideum diagnosed by magnetic resonance imaging - Case report and review of the literature

Study Design. The first case of a synovial cyst of the upper cervical spine associated with os odontoideum diagnosed by magnetic resonance imaging is presented. Objectives. To evaluate distinct magnetic resonance imaging findings of a c ervical synovial cyst located anterior to the cord and discuss its associat ion with os odontoideum. These findings may guide further investigations. Background. Synovial cysts of the spine are uncommon findings. They occur m ostly dorsolaterally and with greatest frequency in the lumbar spine and ar e rarely symptomatic. No association with os odontoideum has been reported before. Methods. A single subject with symptoms of deterioration in his hand functi ons was examined by a 2.0-T magnetic resonance imager. Results. Magnetic resonance imaging of the cervical spine showed an os odon toideum connected to the body of C2 by a synovial joint that had a cystic e xtension posteriorly compressing the cord. Conclusion. Synovial cysts should be considered in the differential diagnos is of an extradural mass of the upper cervical spine. Magnetic resonance im aging should be the choice in the investigation of such cases.