Transdural approach for calcified central disc herniations of the upper lumbar spine. Technical note.

Disc herniations of the upper lumbar spine (L1-2 and L2-3) have a frequency of 1 to 2% of all disc herniations. During posterior discectomy after laminectomy, significant manipulation of the exiting nerve root is unavoidable because of the narrow lamina and the difficulty in mobilizing the nerve root. The authors adopted a transdural approach in patients with calcified central disc herniation at the L1-2 level to reduce the risk of nerve root injury. Four patients suffering from radiating pain together with back pain were treated using the transdural approach. Preoperative neuroimaging studies revealed severe central disc herniation with calcification at the L1-2 level. After laminectomy or laminotomy, the incised dura mater was tacked, and the cauda equina rootlets were gently retracted. An intentional durotomy was performed over its maximal bulging of the ventral dura. After meticulous dissection of dense adhesions between the disc herniation and the dural sac, adequate decompression with removal of calcified disc fragments and osteophytes was accomplished. Clinical symptoms improved in all patients. Postoperative permanent cerebrospinal fluid leakage and pseudomeningocele were not observed, and no patient had a progressive lumbar deformity at an average follow-up of 53 months. Transient mild motor weakness and sensory change were observed in two patients postoperatively; however, these symptoms resolved completely within 1 week. The posterior transdural approach offers an alternative in central calcified upper lumbar disc herniation when root retraction is dangerous.