Reduction of rheumatoid periodontoid pannus following posterior occipito-cervical fusion visualised by magnetic resonance imaging.

Nine patients (four females and five males) with chronic rheumatoid arthritis (RA) and atlanto-axial (AA) instability subjected to occipito-cervical fusion were evaluated clinically and radiologically. All of them had soft tissue formation (pannus) around the odontoid peg. The age ranged from 50 to 79 years (mean: 66). The duration of the RA disease was 3-48 years (mean: 18.5). All patients were seropositive. Both conventional radiography and magnetic resonance imaging (MR) were performed pre- and postoperatively. All fusions except one were stable. One patient was re-fused after 2 months because of wire break. With regard to pain all patients had improved and eight were pain free. Six patients who experienced signs of myelopathy prior to the fusion had improved at follow up. MR revealed reduction of pannus in all nine cases. This was obvious in one patient within 6 weeks postoperatively. The MR findings of a reduction or even disappearance of pannus following posterior fusion should decrease the need for transoral surgery.