Epidural block–induced ligamentum flavum hematoma mimicking epidural hematoma in the lumbar spine: a case report

Background contextThe ligamentum flavum may undergo various pathologic changes, including hypertrophy, calcification, ossification, and cyst formation. Ligamentum flavum hematoma (LFH) is a rare cause of spinal nerve root or cord compression and usually occurs in the lumbar spine. We report a 66-year-old woman with LFH occurring after an epidural block, mimicking epidural hematoma on lumbar spine magnetic resonance imaging (MRI).PurposeTo document MRI findings of epidural block–induced LFH mimicking epidural hematoma.Study design/settingA case report.MethodsA 66-year-old woman presented with a 6-month history of pain in the left buttock and suffered abrupt weakness and numbness in her left leg after an epidural block procedure without any other trauma history. Lumbar spine MRI with enhancement showed a hematoma-like mass in the posterior epidural space at L3–L4 level.ResultsThe patient underwent a left hemilaminectomy at the L3 level, and a surgeon found a small hematoma between inner and outer walls of ligamentum flavum instead of an epidural hematoma and performed the removal of the hypertrophied ligamentum flavum including the intraligamentary lesion. Histopathologic examination confirmed the lesion as hematoma in the left ligamentum flavum. After surgery, the patient recovered without significant neurologic deficit.ConclusionsEpidural block–induced LFH can mimic posterior epidural hematoma on MRI. Careful evaluation of hematoma, location, and imaging findings is required for accurate diagnosis.