Posterior epidural migration of herniated lumbar disc fragment: a literature review

Herniated disc fragments' migration to posterior epidural locations is a very rare pathological condition, and the mechanism is not well understood. Posterior epidural migration may lead to serious neurologic problems; however, its diagnosis and treatment are challenging. We searched PubMed and Google Scholar, using various keyword combinations, and found 111 cases of posterior epidural disc migration in the lumbar region reported between 1973 and 2018. There were 89 (80.2%) men and 22 (19.8%) women. The mean age at surgery was 54.05 years (range, 26-83 years); the mean duration of complaints was 26.3 days. The locations were at the L3-L4 level in 41 cases (36.9%), the L4-L5 level in 37 (33.3%), the L2-L3 level in 21 (18.9%), the L5-S1 level in 8 (7.2%), and the L1-L2 in 4 (3.6%). The disc fragment appeared as hypointense and isointense in 60.3% and 33.8%, respectively, of cases in T1-weighted magnetic resonance imaging (MRI) and as hyperintense in 68.5% of cases on T2-weighted MRI. The initial symptoms were cauda equina syndrome, radiculopathy, and low back pain in 58 (52.2%), 52 (46.8%), and 12 (10.8%) patients, respectively. In addition, 107 patients (96.4%) underwent surgical treatment and 4 (3.6%) underwent conservative treatments, with total recovery, and subtotal recovery in 73 (65.8%), and 38 (34.2%), respectively. We found significant differences between patients at different ages with regard to the level of disc herniation (eta=0.405, p=.001): patients with a higher level of disc herniation were, on average, older. There was no significant difference in outcome between male and female patients, chi(2)(1)=0.591, p=.469, or between patients with upper and lower lumbar spine, chi(2)(1)=0.027, p>.999. Careful history documentation, clinical examinations, and contrast material-enhanced MRI with laboratory tests could help reveal herniated disc fragment and rule out several other pathological processes. In most cases, surgical treatment produced favorable outcomes.