Intradural Lumbar Disc Herniation with Focal Intraspinal Gas and Pseudocystic Morphology: Radiologic-Operative-Pathologic Correlation

Abstract

Intradural lumbar disc herniation is rare and frequently recognized only during surgery because its clinical and imaging features may resemble other intradural lesions. A 71-year-old man presented with progressive left-sided lumbosciatica without neurological deficit. Magnetic resonance imaging showed a pseudocystic intradural lesion at L4–L5 with marked displacement of the cauda equina, and computed tomography demonstrated focal gas in the ventral spinal canal at the same level. Extradural exploration did not reveal disc material sufficient to explain the compression. Dorsal durotomy released air and exposed a pseudocystic lesion containing disc material. After resection, a ventral dural defect communicating with the disc space was visualized and reinforced with a fibrin sealant patch. Histopathology confirmed degenerated disc tissue with granulation tissue and pseudocystic fibrous tissue. The patient remained neurologically intact and experienced complete resolution of the presenting radicular symptoms. Gas-containing cystic intradural disc herniation has been reported previously; the value of this case is the concordance of routine magnetic resonance and computed tomography findings with air release, direct visualization of the migration route, and histopathologic confirmation. Focal intraspinal gas does not establish intradural migration by itself, but in the appropriate anatomic setting it can strengthen diagnostic suspicion and surgical planning.