Ventral Lumbar Synovial Cyst Causing Cauda Equina Compression: Case Report and Literature Review

Abstract

Background: Juxtafacet spinal cysts are cystic synovial lesions that often are indistinguishable clinically or radiologically and require histopathology analysis to confirm the diagnosis. Lumbar synovial cysts usually arising from the synovium of the facet joints. They have been described posterolaterally or rarely in the posterior midline. However, we describe the first synovial cyst ventral to the dural sac.

Case description: We report a lumbar 3-4 lesion causing cauda equina compression in a 57-year-old man who presented with a 3-month history of low back pain and bilateral sciatica, intermittent urinary incontinence, and erectile dysfunction. Preoperative magnetic resonance imaging suggested prolapsed disc, after decompression, histological analysis of the fragment confirmed a synovial cyst.

Conclusions: Hitherto synovial cysts have not been reported anterior to the dural sac. We describe a lumbar ventral cystic mass with cauda equina compression that mimicked a disc prolapse due to synovial metaplasia. The patient had urgent decompression with subsequent resolution of the symptoms.

Keywords: Cauda equina; Lumbar spine; Synovial cyst.