Chronic dura erosion and intradural lumbar disc herniation: CT and MR imaging and intraoperative photographs of a transdural sequestrectomy.

Abstract

A 47-year-old male with a history of recurrent low-back pain presented with acute left radiculopathy. The CT and MR scans showed a severe osteochondrosis of the L4/5 segment, a broad protrusion of the disc annulus and extrusion of nucleus material into the spinal canal on the left side. The caudally dislocated sequester pieces were visualised intradurally and the intraoperative finding confirmed this rare pathology. After dorsal durotomy-free sequester material was found between the nerve rootlets within the subarachnoid space and altogether ten fragments were removed. Further transdural exploration visualised ventrally a round dura defect surrounded by a thickened arachnoid layer with enlarged veins as a sign of a chronic erosive process. Patients history, imaging and the intraoperative findings support the thesis, that chronic degenerative disc disease and adhesions between the posterior longitudinal ligament and the dura are the predisposing pathogenetic factors for an intradural disc herniation. Intradural disc herniation is a rare condition and requires durotomy to remove the pathology. Therefore an actual high resolution MRI is mandatory in all cases of intraspinal space occupying lesions.