Intradural disc herniation at L5 level mimicking an intradural spinal tumor

Abstract

Intradural lumbar disc herniation is a rare complication of disc disease. The reason for the tearing of the dura matter by a herniated disc is not clearly known. Intradural disc herniations usually occur at the disc levels and are often seen at L4-L5 level but have also been reported at other intervertebral disc levels. However, intradural disc herniation at mid-vertebral levels is rare in the literature and mimics an intradural extramedullary spinal tumor lesion in radiological evaluation. Although magnetic resonance imaging (MRI) with gadolinium is useful in the diagnosis of this condition, preoperative correct diagnosis is usually difficult and the definitive diagnosis must be made during surgery. We describe here a 50-year-old female patient who presented with pain in the lower back for 6 months and a sudden exacerbation of the pain that spread to the left leg as well as numbness in both legs for 2 weeks. MRI demonstrated an intradural mass at the level of L5. Laminectomy was performed, and subsequently durotomy was also performed. An intradural disc fragment was found and completely removed. The patient recovered fully in 3 months. Intradural lumbar disc herniation must be considered in the differential diagnosis of mass lesions in the spinal canal.

Fig. 1

T1- and T2-weighted images in non-contrast saggital and axial MRI demonstrating a huge isointense mass-like lesion, located centrally to the left at L5 level, which nearly compresses the entire spinal canal and a beak-like appearance in the axial T1- and T2-weighted images (arrow)

Fig. 2

Gadolinium-enhanced MRI, T1-weighted image showing ring enhancement (arrow) of the mass; T2-weighted image revealing no peripheral or homogeneous enhancement of the mass

Fig. 3

Intraoperative image demonstrating the peripheral displacement of the adherent cauda equine nerve roots by intradural disc fragment (arrow)