Journal Belge de Radiologie vol:72 issue:5 pages:373-6
Intraspinal ganglions or synovial cysts most frequently involve the L4-L5 level and the adjacent facet joint reveals characteristic alterations of osteo-arthritis. These cysts usually present with pain, but without additional sensory or motor findings. They cannot be diagnosed on the basis of conventional radiology; myelography shows a filling defect adjacent to the affected facet joint, and the differential diagnosis includes several common and uncommon entities. The CT appearance is however strongly characteristic, showing a cystic structure with occasionally a calcification within its wall. There often is compression of the adjacent dural sac or nerve roots.