Posterior epidural disc fragment masquerading as spinal tumor: Review of the literature

BACKGROUND: Posterior epidural lumbar disc fragment is infrequent because of anatomical barriers, and it is difficult to diagnose posterior epidural lumbar disc fragment because of its rare incidence and the ambiguity of radiologic evaluations. And it is difficult to differentiate it from other diseases such as spinal tumors. OBJECTIVE: Differential diagnosis of posterior epidural lumbar disc fragment is clinically important because its diagnosis can affect treatment and prognosis. To investigate the incidence, anatomical concern, etiology, symptom, diagnostic tool, management and prognosis of posterior epidural lumbar disc fragment, we reviewed articles including case report. METHODS: We performed a search of all clinical studies of posterior epidural lumbar disc fragment published to date. The following keywords were searched: Posterior epidural lumbar disc fragment, disc migration, posterior epidural disc, extradural migration, dorsal epidural migration, sequestrated disc, and disc fragment. RESULTS: We identified 40 patients of posterior epidural lumbar disc fragment from 28 studies. The most common presentation of posterior epidural lumbar disc fragment was sudden onset radiculopathy (70.0%), followed by cauda equina syndrome (27.5%). The most frequently used diagnostic modality was magnetic resonance imaging (MRI), conducted in 36 cases (90.0%), and followed by computed tomography in 14 cases (35.0%). After the imaging studies, the preoperative diagnoses were 45.0% masses, 20.0% lesions, and 12.5% tumors. Characteristic MRI findings in posterior epidural lumbar disc fragment are helpful for diagnosis; it typically displays low signals on T1-weighted images and high signals on T2-weighted images with respect to the parent disc. In addition, most of the disc fragments show peripheral rim enhancement on MRI with gadolinium administration. Electrodiagnostic testing is useful for verifying nerve damage. Surgical treatment was performed in all cases, and neurologic complications were observed in 12.5%. CONCLUSIONS: As posterior epidural lumbar disc fragment could be masqueraded as spinal tumor, if rim enhancement is observed in MRI scans with sudden symptoms of radiculopathy or cauda equina syndrome, it should be taken into consideration. Early diagnosis can lead to early surgery, which can reduce complications.