Intradural lumbar disc herniation: illustrative case

Abstract

Background: Accounting for less than 0.4% of disc herniations, intradural lumbar disc herniations (ILDHs) are a rare occurrence primarily described as a complication after lumbar spine surgery. It is speculated that the herniation may propagate intradurally from either an unrecognized dural defect after initial surgery or as a result of adhesions between the dura and posterior longitudinal ligament. This report explores the etiology, presentation, diagnostic evaluation, and treatment of ILDH along with a case report and microsurgery video.

Observations: A 67-year-old patient who 1 year earlier had undergone an L2-5 laminectomy and L2-3 decompression with no known complications presented with low back pain and radiating right leg, buttock, and groin pain for 1 month. Physical examination indicated no numbness or weakness. Magnetic resonance imaging demonstrated a large ILDH. A transforaminal interbody fusion was performed followed by a durotomy, ILDH removal, and dural closure. A ventral dural defect was found and repaired during the procedure.

Lessons: The treatment for ILDH is laminectomy with dorsal durotomy. Because ILDH has rarely been described in literature, understanding its presentation is crucial for prompt identification and management.

Keywords: PLL = posterior longitudinal ligament; CSF = cerebrospinal fluid; ILDH; ILDH = intradural lumbar disc herniation; LDH = lumbar disc herniation; MRI = magnetic resonance imaging; cauda equina syndrome; intradural lumbar disc herniation; spine surgery.

FIG. 1.

Operative sketch of intradural lumbar disc herniation drawn by Dandy in 1942. Reproduced with permission from JAMA. Serious complications of ruptured intervertebral disks. JAMA 1942;119(6):474.

FIG. 2.

Lumbar MRI. A: Sagittal T2-weighted MRI of the lumbar spine showing large and small soft tissue masses in the spinal canal at L2–3 with widening of the CSF about the superior and inferior border of the larger mass. The cauda equina is also tethered to the distal mass. B: Postcontrast image shows areas of rim and septation enhancement about the dominant superior soft tissue mass. C: Axial T2-weighted MRI shows severe L2–3 compression of the spinal cord rootlets and CSF effacement.

FIG. 3.

Operative images. A: Intraoperative view after durotomy showing disc fragments (solid white arrows) wrapped in the nerve rootlets (dashed white arrow). B: View after all disc fragments have been removed and the repaired defect in the right lateral dural wall (dashed yellow arrow). C: Gross pathologic specimen of herniated disc after removal.

FIG. 4.

Radiographic signs of ILDH. A: The Y-sign on MRI (yellow lines). B: The hawk beak sign on MRI (yellow line). C: Intradural gas on computed tomography (yellow arrow).