Use of methylene blue discography in transforaminal endoscopic discectomy for cranially migrated lumbar disc herniation: A case report

Cranially migrated foraminal lumbar disc herniations remain technically demanding during transforaminal endoscopic discectomy, because the narrow working corridor restricts direct visualization of extruded fragments. We describe a 61-year-old woman with refractory left-sided radiculopathy and progressive motor deficit. Magnetic resonance imaging showed a left L4-L5 foraminal disc extrusion with an annular tear and cranial migration to the upper segment of the neuroforamen, classified as Lee zone 1, causing severe foraminal narrowing with compression and deformity of the exiting nerve root. Before resection, intradiscal injection of iodinated contrast and methylene blue under fluoroscopic guidance stained 2 extruded fragments and allowed targeted removal without neural injury. Multimodal intraoperative neurophysiological monitoring documented progressive recovery of motor-evoked potential amplitudes during decompression. The patient was discharged the same day. At 1 month the Oswestry Disability Index had improved from 86% to 10% and the visual analog scale from 10 to less than 1, and the improvement was sustained at 8 months. In this patient, methylene blue discography appeared to facilitate localization of the migrated fragments within a constrained foraminal corridor, while neurophysiological monitoring added real-time functional assessment of neural decompression. Comparative studies are needed before either adjunct can be recommended routinely in this herniation subtype.