Rapid Neurologic Deterioration due to an Enlarging Thoracic Spine Synovial Cyst: A Case Report.

CASE: We present the case of a 69-year-old man arriving to our clinic after a previous outside hospital recommendation of L1-S1 fusion due to degenerative scoliosis. A thoracic spine synovial cyst was identified through magnetic resonance imaging. The patient had rapid progression of his neurologic deficit due to cyst enlargement. We elected to perform cyst decompression and instrumented fusion of the involved thoracic segment. The patient rapidly regained full neurologic function. After the one-year follow-up, he remained asymptomatic with no progression of thoracolumbar degeneration. CONCLUSIONS: Thoracic spine synovial facet cysts are uncommonly encountered. Decompression alone or decompression and fusion are both viable treatment options depending on the surgeon's assessment of spine stability after decompression. This diagnosis should be considered in patients presenting with unilateral lower extremity upper motor neuron findings.