Dorsal epidural intervertebral disk herniation with atypical radiographic findings: case report and literature review

Abstract

Background/objective: Intervertebral disk herniation is relatively common. Migration usually occurs in the ventral epidural space; rarely, disks migrate to the dorsal epidural space due to the natural anatomical barriers of the thecal sac.

Design: Case report.

Findings: A 49-year-old man presented with 1 week of severe back pain with bilateral radiculopathy to the lateral aspect of his lower extremities and weakness of the ankle dorsiflexors and toe extensors. Lumbar spine magnetic resonance imaging with gadolinium revealed a peripheral enhancing dorsal epidural lesion with severe compression of the thecal sac. Initial differential diagnosis included spontaneous hematoma, synovial cyst, and epidural abscess. Posterior lumbar decompression was performed; intraoperatively, the lesion was identified as a large herniated disk fragment.

Conclusions: Dorsal migration of a herniated intervertebral disk is rare and may be difficult to definitively diagnose preoperatively. Dorsal disk migration may present in a variety of clinical scenarios and, as in this case, may mimic other epidural lesions on magnetic resonance imaging.

Figure 1

Magnetic resonance image of the lumbar spine showing a large dorsal epidural lesion. (A) Sagittal T1-weighted images after gadolinium injection. (B) Axial T1-weighted image after gadolinium injection show rim enhancement. (C) Axial T2-weighted images show severe thecal sac compression.