Two types of laminoplasty for cervical spondylotic myelopathy at multiple levels.

Based on the results from pathological analysis and computer simulations by means of finite element analysis that were reported before, the pathological changes of cervical spondylotic myelopathy (CSM) seem to begin at the posterolateral parts of the spinal cord, because the mechanical stress is mainly concentrated in these parts. With progression of the compression, the pathological changes become distributed to a wider area of the spinal cord. In patients with spinal canal stenosis, these changes spread to multiple levels of the cervical spine. Therefore, posterior decompression surgery at multiple levels such as cervical laminoplasty is thought to be reasonable.