We describe a case of atlantoaxial joint subluxation and cervical myelopathy in a patient with rheumatoid arthritis. Magnetic resonance imaging (MRI) demonstrated a large periodontoid pannus compressing the upper cervical cord. Neurological function improved rapidly after treatment with intravenous pulse corticosteroids given before surgical fusion of the cervical spine. Post operative MRI showed a significant reduction in size of the pannus.