Endoscopically Assisted Release Surgery for Idiopathic Spinal Cord Herniation: Technical Case Instruction.

Background and importance: Idiopathic spinal cord herniation through a defect in the ventral dura mater is rare and typically results in progressive myelopathy. Various surgical procedures to release the tethered spinal cord can prevent the progression of myelopathy; however, the optimal procedure has not yet been established. We describe techniques using endoscopic assistance to minimize spinal cord manipulation.

Clinical presentation: A 60-year-old woman presented with Brown-Séquard syndrome. Magnetic resonance imaging demonstrated ventral displacement of the spinal cord at T3-4. Right T2, T3, T4, and T5 hemilaminectomies and T4 pediculectomy were performed. After paramedian durotomy and transection of the dentate ligament, we identified a defect in the inner layer of the dura mater ventrally and found the spinal cord incarcerated in a pocket between the inner and outer layers. The spinal cord was adherent to the dura at the caudal end of the defect. The defect was extended caudally on the right under microscopic observation. On the left, which could not be visualized under the microscope, the adhesions were dissected under endoscopic guidance. After complete spinal cord untethering, the defect was closed using collagen matrix. The patient's motor weakness fully recovered, and she was walking independently at the time of discharge.

Conclusion: Endoscopic assistance for release of thoracic spinal cord herniation is useful for minimizing intraoperative spinal cord manipulation.