Spinal epidural cystic lesions

Spinal epidural cystic lesions are fluid-filled lesions within the spinal canal but outside the thecal sac. Their clinical significance is as a potential contributor to spinal cord or nerve root impingement. Simple appearing spinal epidural cysts may represent several entities that differ by origin:

• cysts related to interspinous bursitis ¹
• discal cysts ¹ and disc sequestration ⁷
• extradural spinal arachnoid cysts (Nabor type I spinal meningeal cysts, sometimes referred to as spinal extradural cysts, extra-arachnoid fluid collections, or pseudomeningoceles) ^2,3
• facet synovial cysts (sometimes referred to generically as lumbar extradural cysts, or specifically as juxtafacet cysts or spinal ganglion cysts) ^1,4,5
• cysts of the ligamentum flavum ^1,6
• perineural cysts

More complex fluid collections can also be included in the differential of spinal epidural cyst-like lesions:

• varices ⁷
• hemangioma (vascular malformation) ⁸
• hematoma
• abscess