Herniation and Entrapment of a Nerve Root Secondary to an Unrepaired Small Dural Laceration at Lumbar Hemilaminectomies

Study Design The authors encountered a unique case of nerve root herniation 9 days after multiple lumbar partial hemilaminectomies with discectomy were performed for lumbar canal stenosis combined with lumbar disc hernia. Objective The treatment of this patient involved surgical repair even though the dural laceration was small and the arachnoid was intact. Summary of Background Data There have been no reports of nerve root herniation into the facet joint through the arachnoid space after laminectomy, except in cases of extradural distention of the arachnoid membrane. Methods The patient presented with weakness of the right lower extremity and underwent partial hemilaminectomies and discectomy for lumbar canal stenosis. Nine days after surgery, he suddenly experienced severe pain in the left S1 region. Neither myelography nor computed tomography-myelography revealed pathologic findings before the second operation. At surgery, herniation of the S1 nerve root was found. Surgical correction of the herniated nerve root at the level of the left L5 vertebra was performed. Results This correction completely relieved the pain in the left S1 region. Conclusion This herniation resulted from an unrepaired minor dural laceration. The arachnoid membrane was intact during the first operation. Even a small tear in the spinal dura requires surgical closure to prevent herniation and entrapment of a nerve root. It is necessary to repair even small dural lacerations with no spinal fluid leakage during spinal surgery.