Images below require Macromedia's Flash Player to view

Neuroradiology Case of the Week

Case 393

March 2009

Ashwani K. Sharma, MD, and PL Westesson, MD, PhD, DDS

Clinical Presentation: Patient is an 80-year-old female patient with a history of trauma due to a fall with loss of consciousness.

Imaging Findings: Extensive degenerative changes involving the cervical spine especially at the C2 level where there are a few areas of lysis involving the C2 vertebral body in its posterior aspect. There is also a large component of pannus which is associated with the C2 vertebral body anteriorly and also encompassing it posteriorly. The soft tissue pannus appears to be causing narrowing of the spinal canal and may be causing compression
of the cord at this level. There are a few small ossific fragments within the soft tissue pannus which may be due to the degenerative changes within the C2 vertebral body.
     Soft tissue lesion is noted around C2 vertebral body and dens. The soft tissue is hypointense on both T1 and T2-weighted images. It is causing cord compression and atrophy on the right side.

Diagnosis: Pannus at C2

Discussion: Periodontoid pseudotumor or pannus is considered to be an inflammatory mass most frequently associated with rheumatoid arthritis (RA) [1]. Although often asymptomatic, mechanical compression of the upper cervical spinal cord may result in cervical myelopathy [2,3]. It has been shown that such compression of the spinal cord can be caused not only by atlantoaxial subluxation itself but also by formation of a periodontoid pannus mass [2,4]. In cases with large periodontoid pannus masses causing life-threatening compression of the medulla oblongata or the high cervical spinal cord, transoral transpharyngeal odontoidectomy and removal of the pannus for decompression of the neuraxis may be necessary [3]. Nevertheless, spontaneous resolution of the pannus masses after posterior atlantoaxial or occipitocervical fusion has been well documented in patients with RA [2,4,5].
     Differential diagnosis includes noninflammatory masses at C1–C2 as retro-odontoid disk herniation, transverse ligament degeneration, synovial cysts, ganglion cysts, and degenerative articular cysts [6,7]. Pseudotumor or pannus can occur in patients on dialysis and may be due to amyloidosis [8].
     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.

References:

1. Lagares A, Arrese I, Pascual B, Gòmez PA, Ramos A, Lobato RD. Pannus resolution after occipitocervical fusion in a non-rheumatoid atlanto-axial instability. Eur Spine J. 2006 Mar;15(3):366-9. [PubMed]
2. Milbrink J, Nyman R. Posterior stabilization of the cervical spine in rheumatoid arthritis: clinical results and magnetic resonance imaging correlation. J Spinal Disord. 1990 Dec;3(4):308-15. [PubMed]
3. Sukoff MH, Kadin MM, Moran T. Transoral decompression for myelopathy caused by rheumatoid arithritis of the cervical spine. Case report. J Neurosurg. 1972 Oct;37(4):493-7. [PubMed]
4. Larsson EM, Holtas S, Zygmunt S. Pre- and postoperative MR imaging of the craniocervical junction in rheumatoid arthritis. AJR Am J Roentgenol. 1989 Mar;152(3):561-6. [PubMed]
5. Zygmunt S, Säveland H, Brattström H, Ljunggren B, Larsson EM, Wollheim F. Reduction of rheumatoid periodontoid pannus following posterior occipito-cervical fusion visualised by magnetic resonance imaging. Br J Neurosurg. 1988;2(3):315-20. [PubMed]
6. Crockard HA, Sett P, Geddes JF, Stevens JM, Kendall BE, Pringle JA. Damaged ligaments at the craniocervical junction presenting as an extradural tumour: a differential diagnosis in the elderly. J Neurol Neurosurg Psychiatry. 1991 Sep;54(9):817-21. [PubMed]
7. Sze G, Brant-Zawadzki MN, Wilson CR, Norman D, Newton TH. Pseudotumor of the craniovertebral junction associated with chronic subluxation: MR imaging studies. Radiology. 1986 Nov;161(2):391-4. [PubMed]
8. Rousselin B, Helenon O, Zingraff J, Delons S, Drueke T, Bardin T, Moreau JF. Pseudotumor of the craniocervical junction during long-term hemodialysis. Arthritis Rheum. 1990 Oct;33(10):1567-73. [PubMed]