Intradural disc herniation: Radiographic findings and surgical results with a literature review

• We describe four cases of IDH, including three with lumbar hernia and one with thoracic hernia.
• Preoperative characteristic imaging findings can be useful for diagnosis, but intraoperative findings are required for definitive diagnosis.
• It is useful to confirm the anterolateral aspect of the dural sac from the annulus fibrosus of the intervertebral disc during surgery.

ObjectiveTo report a series of four cases of intradural disc herniation (IDH) with a review of the literature.Summary of background dataIDH is a rare type of disc herniation. Preoperative diagnosis is difficult and IDH is only confirmed during surgery in most cases. Here, we describe four cases of IDH, including three with lumbar hernia and one with thoracic hernia.MethodsA retrospective chart review, surgical database query, and review of radiology reports are presented for each case, along with a literature review of IDH.ResultsTwo of the four patients had a history of surgery at the same spinal level. Ring enhancement in gadolinium-enhanced MRI, an air image in computed tomography, and complete block in myelography were observed in the series. Surgery was performed with a transdural approach in all patients. One patient underwent transforaminal lumbar interbody fusion after postoperative recurrence. Three patients with lumbar involvement had nerve root symptoms preoperatively, but showed symptomatic improvement in the early postoperative period. In contrast, the patient with thoracic involvement had preoperative muscle weakness due to myelopathy symptoms, and had residual symptoms after surgery.ConclusionsIDH is a rare disease and characteristic imaging findings can be useful for diagnosis. Intraoperative findings lead to a definitive diagnosis in many cases and recognition of the pathological characteristics of IDH is important.