Posterior and anterior epidural and intradural migration of the sequestered intervertebral disc: Three cases and review of the literature.

Context: Dorsal migration of the sequestered lumbar intervertebral disc is an unusual and underrecognized pattern of lumbar disc herniation associated with pain and neurological deficit.Findings: Three patients presented with lower limb- and low back pain. MR imaging showed intracanalicular mass lesions with compression of the spinal cord and allowed precise localization of lesions in the extradural or intradural space. Diagnosis was straightforward for the patients with the posterior and anterior epidural disc fragments, whereas various differential diagnostic considerations were entertained for the patient with the intradural mass lesion. All patients underwent surgical removal of the sequestered disc fragments, and recovered full motosensory function. Surgical repair of the dura mater due to CSF leak was required for the patient with intradural disc herniation.Conclusion/clinical relevance: Posterior and anterior epidural, and intradural disc migration may manifest with clinical symptoms indistinguishable from those associated with non-sequestered lumbar disc hernias. Missed, migrated disc fragments can be implicated as a cause of low back pain, radiculopathy or cauda equina syndrome, especially in the absence of visible disc herniation. A high index of suspicion needs to be maintained in those cases with unexplained and persistent symptoms and/or no obvious disc herniation on MR images.