Key Clinical MessageMRI remains the best tool in the diagnosis of this disease entity however preoperative diagnosis remains a difficult task. A high degree of suspicion is raised when intraoperative findings and preoperative image description become incompatible.AbstractLumbar disc herniation into the dural space is a rare phenomenon of lumbar disc degeneration with an unclear remaining pathogenesis. Intraoperative ultrasonography and histopathological examination of resected specimen help in the diagnosis of intradural disc herniation. Prompt surgery is recommended due to the high incidence of cauda equina syndrome.