Pannus resolution after occipitocervical fusion in a non-rheumatoid atlanto-axial instability

Abstract

Periodontoid pseudotumor or pannus is considered to be an inflammatory mass most frequently associated with rheumatoid arthritis. Transoral resection of the pannus has been the treatment of choice for patients with associated myelopathy, followed in many instances by posterior stabilization. However, some authors have reported resolution of pannus associated with rheumatoid arthritis and other forms of chronic atlanto-axial instability only after posterior stabilization. We report a case of a 69-year-old man who presented with a rapidly progressing myelopathy due to a retro-odontoid mass produced by chronic atlanto-axial instability associated with an occipital assimilation of C1 and tight posterior fossa. An urgent posterior fossa craniectomy followed by occipitocervical fixation was performed. After surgery, the patient's clinical condition improved and 1 year after surgery was asymptomatic, walked without any help and had normal strength. Control MR showed complete resolution of the retro-odontoid pannus.

Fig. 1

Preoperative cervical X-ray showing an assimilation of the posterior arch of C1 and an increase of the atlanto-dental interval suggesting atlanto-axial instability

Fig. 2

Preoperative MR showing an isointense retro-odontoid mass in sagital (a) and axial (d) T1 image, which caused severe myelopathy with cord edema in sagital T2 image (b). Both the mass and the cord enhanced after contrast administration. Sagital (c) and axial (e and f) contrast T1 images

Fig. 3

Postoperative CT 3-D reconstruction showing posterior fossa decompression and occipito cervical fixation

Fig. 4

MR performed 2 weeks after surgery, showing adequate posterior decompression and a slight reduction in the retro-odontoid mass. a and b sagital T2; c and d axial T2

Fig. 5

MR performed 1 year after surgery showing the resolution of both the retro-odontoid mass and cord compression. a sagital T1; b sagital T2; c and d axial T2