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Radiologic Findings: Sagittal T/1 images show inhomogeneity within the thecal sac with post operative changes (A). The post gadolinium T/1 sagittal image shows an enhancing ring within the thecal sac (B). The axial T/1 post contrast demonstrates the process bilaterally, larger on the right than left (C).
Diagnosis: Bilateral synovial cysts.
Discussion: On the basis of sagittal post contrast T/1 study the other diagnoses such as schwannoma, intradural metastasis, extruded disc, ependymoma or infectious cyst should be entertained. The proximity to facet joints makes the diagnosis more likely. The cysts are degenerative in nature and are common after 5th decade. They may bleed and have different signal on different techniques.
References:
Silbertgeit R, et al. Lumbar Synovial Cystis: Correlation of Myelographic, CT, MR
and Pathologic Findings. AJNR 11:777-779, 1996.
Savits MH, et al. Hypertrophic Synovitis of the Facet Joints Forming a Para-articular Mass
in Case of Herniated Intervertebral Disc. Spine 12:509-510, 1987.
Hemminghytt SD, Daniel DL, Willis AL, Haughton VM. Intraspinal Synvoial Cyst:
Natural History and Prognosis by CT. Radiology 145:375-376, 1982.
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