Cervical Myelopathy: Anterior Approach

Gregory Gebauer, Alan S. Hilibrand, and Maurice Goins

Myelopathy is a constellation of symptoms resulting from spinal cord dysfunction due to compression on the spinal cord. Symptoms are often vague and tend to progress over time. The spinal cord can be compressed from anterior structures, such as disk herniations or osteophytes, or from posterior structures, including the facet joints and ligamentum flavum. While mild cases can be treated with observation, most cases require surgical decompression. Anterior, posterior, and combined approaches can be used depending on the location of the compression, extent of disease, number of levels involved, posture of the cervical spine, and other patient and disease related factors.

In its normal state, the cervical spine is in lordotic posture as a result of the anterior disk height being slightly greater than the posterior disk height. The disk functions to dissipate the energy of vertical forces, but with aging it sustains weakening of the annular fibers, leading to posterior protrusion, loss of disk height, and redundancy of the ligamentum flavum, which encroaches on the spinal canal and decreases the space available for the spinal cord. In addition, decreased disk height can lead to loss of the normal lordotic curvature and development of a kyphotic posture. This causes the spinal cord to be further draped over anterior structures and can lead to increased pressure on the cord.

Biomechanically, disk degeneration transfers stress to the vertebral end-plates, resulting in the formation of osteophytes along the margins of the disk space and behind the uncovertebral joints. By age 50, at least half of patients will have radiographic evidence of spondylosis. Although most will remain asymptomatic, in some individuals these may contribute to further compression of the spinal canal.