Upper Lumbar Intradural Disc Herniation: A Rare Case Report and Etiologic Analysis

Abstract

Background: Intradural disc herniation (IDH) is a rare type of disc degeneration that infrequently affects the upper lumbar spine. Pre- and intraoperative diagnosis and surgical management of IDH are challenging. The present case study provides insight into these aspects of upper lumbar IDH and discusses possible mechanisms.

Case description: A 63-year-old female with a history of chronic lower back and leg pain presented with an acute lumbar sprain that had occurred 1 month prior. The pain progressed and spread to the front of the left thigh, which affected her ability to lift her leg when ascending/descending stairs. Sagittal gadolinium-enhanced magnetic resonance imaging (MRI) revealed a disc protruding into the ventral dural sac showing a hawk-beak sign, and the posterior edge of the disc annulus and local posterior longitudinal ligament was broken. Total L2 laminectomy was performed, and the dorsal side of the dural sac was exposed and incised to enable exploration of the ventral side of the dura. We found two free fragments protruding into the inner wall of the dura through the left ventral dura mater defect. After carefully and completely removing the mass, we repaired the defect and performed internal fixation. Postoperative pathologic analysis confirmed that the mass was nucleus pulposus tissue from the degenerated disc. The patient's pain significantly improved after surgery, and she was able to walk normally at the 1-month follow-up.

Conclusion: Upper lumbar IDH is an extremely rare type of disc degeneration. An enhanced MRI scan can provide diagnostic evidence, but the final diagnosis requires surgical exploration of the path of herniation and pathologic examination of the mass lesion.

Keywords: case report; intradural disc herniation; lower back pain; radiating pain; upper lumbar.

Figure 1

Preoperative radiographs showing lumbar degeneration and instability between the L2/3 segments (A, white arrow) and internal fixation to stabilize the local intervertebral space (B).

Figure 2

Sagittal T1-weighted (A) and T2-weighted (B) MR images showing posterior disc fibrous annulus rupture and loss of PLL continuity at the L2/3 level. (C) Enhanced MR image showing a “hawk-beak” sign. White arrows indicate disc herniation and associated radiographic changes.

Figure 3

(A) Axial T2-weighted MR image showing the torn PLL (A, white arrow). (B) Enhanced MR image showing a ring sign (B, white arrow).

Figure 4

(A) A midline durotomy was performed. (B) Smooth surface with hard fragments lodged in the inner wall of the ventral dura (blue arrow). (C) Thinned round defect within the ventral dura (blue arrow). (D) Image showing the sizes of the two herniated disc fragments.

Figure 5

(A) Degenerated fibrocartilage (red box) and hyperplastic inflammatory granulation tissue (blue box) on histopathologic examination (50× magnification). (B) Proliferation of small blood vessels and fibroblasts accompanied by inflammatory cell infiltration (blue box, 100× magnification). (C) Degenerated fibrocartilage and nucleus pulposus tissue (red box, 100× magnification).