Retro-odontoid pseudotumor (pannus) with Forestier’s disease presenting with severe tetraparesis: A case report and literature review

A retro-odontoid pannus is often associated with inflammatory diseases. It can also have a noninflammatory cause due to chronic atlantoaxial instability.Here, we report a patient with diffuse idiopathic skeletal hyperostosis and a severe noninflammatory retro-odontoid pannus who rapidly improved after posterior craniocervical decompression and arthrodesis.Transoral resection of the pannus, followed by posterior stabilization, is a common treatment for this condition. The pannus can, however, also reduce after posterior stabilization alone (e.g., craniocervical decompression).