Circumspinal decompression with dekyphosis stabilization for thoracic myelopathy due to ossification of the posterior longitudinal ligament

Abstract

Study design: Circumspinal decompression with dekyphosis stabilization was prospectively performed with thoracic myelopathy due to ossification of posterior longitudinal ligament (OPLL). Neurologic outcome was reviewed.

Objective: To evaluate how easily, safely, and completely the thoracic OPLL can be removed or floated by circumspinal decompression with dekyphosis stabilization.

Summary of background data: Anterior decompression is the best for the spinal cord recovery to treat thoracic myelopathy caused by OPLL on the concave side of the spinal cord. However, anterior approach for removal of OPLL plaque is technically demanding.

Methods: This is an operative procedure. Wide laminectomy is performed. Bilateral gutters along the dural tube are made using a diamond drill into the vertebral body covering the extent of the OPLL to be removed anteriorly. Posterior instrumentation is applied for stabilization of the spine and reducing thoracic kyphosis by approximately 5 to 10 degrees (dekyphosis stabilization). Four weeks after the first step, anterior decompression is performed with direct vision with the landmark of gutters using an operative microscope, followed by interbody fusion. Fifteen patients with thoracic myelopathy due to OPLL had the first-step operation, and 11 patients underwent circumspinal decompression (both the first and second operation).

Results: Kyphosis in the stabilization area reduced from 30.7 to 24.7 degrees on average in 15 patients. In 2 of the 15 patients, the spinal cord was shifted posteriorly and completely decompressed by only the first-step operation in the postoperative myelography or magnetic resonance imaging. The second-step operation was cancelled, and their Japanese Orthopedic Association scores improved from 6 to 10 points and from 4 to 10.5 point, respectively at final follow-up. In other 13 patients, the spinal cord was still compressed by the OPLL plaque. In 2 of the 13 patients, the second-step operation was cancelled because their general condition was impaired. Their preoperative Japanese Orthopedic Association scores were 2.0 and 2.5, and final scores were 5.5 and 5.5 points, respectively. Remaining 11 patients who underwent circumspinal decompression (both the first and second operation) neurologically improved and maintained from 4.0 points to 9.1 points on average at final follow-up.

Conclusion: The OPLL plaque in the thoracic spine might be most easily, safely, and completely removed or floated, and the spinal cord is circumferentially decompressed through circumspinal decompression with dekyphosis stabilization.