Gas-containing cystic intradural lumbar disc herniation at L1-2, a rare diagnosis confirmed by discography and review of the literature: illustrative case.

backgroundIntradural disc herniation (IDH) is an uncommon clinical entity, composing only 0.26%-0.30% of lumbar disc herniations. Most IDHs occur at L4-5 or L5-S1, and cases at L1-2 are extremely rare. Preoperative diagnosis is often difficult because IDH can mimic an intradural tumor, hematoma, or cyst on MRI. This report presents a rare case of cystic IDH containing intradural gas at L1-2 in which discography confirmed the diagnosis preoperatively. OBSERVATIONS: A 57-year-old man presented with worsening low back pain and bilateral buttock and anterior thigh pain. T1- and T2-weighted MRI demonstrated an intradural mass with low signal intensity at L1-2, displacing the conus medullaris and cauda equina ventrally. CT myelography showed a gas-containing mass surrounded by cauda equina adhesions. Discography revealed contrast leakage into the lesion, confirming IDH. The cystic disc fragment was completely resected by partial laminectomy and durotomy. The symptoms improved postoperatively, with no recurrence observed on follow-up MRI at 1 year. LESSONS: IDH at L1-2 is exceptionally rare. When intradural gas and nerve root displacement are observed, discography can be important in establishing a definitive diagnosis preoperatively. This diagnostic clarity contributes to appropriate surgical planning and contributes to improved clinical outcomes. https://thejns.org/doi/10.3171/CASE25559.