Hemorrhagic Lumbar Synovial Cyst after Microscopic Discectomy.

Intraspinal synovial cysts are rare but they are being documented with increasing frequency due to improvements in radiological imaging. However, hemorrhage into synovial cysts is uncommon, and affected patients may present with acute onset radiculopathy. This type of hemorrhage is known to result from rupture of fragile neoangiogenic vessels in the cyst wall, due to a traumatic event or anticoagulant therapy. Here, the authors present a rare case of hemorrhagic lumbar synovial cyst caused by spinal instability after microscopic discectomy. To the best of the authors' knowledge, this is the first report of hemorrhagic lumbar synovial cyst caused by spinal instability following microscopic discectomy in the absence of a traumatic event or anticoagulant therapy. We discuss the pathophysiological mechanism of this uncommon entity and provide a review of the literature.