encroachment upon the spinal cord or nerve roots.
As described earlier, the sources of pain from spondylosis include nerve root compression or stress injury, or inflammation of the osseoliga-mentous component of the motion segment. The character and distribution of the pain often define the source of the pain. Neural compressive pain is usually quite well defined and, if the distribution of symptoms correlates with compressive pathology on the imaging studies, an affirmative outcome can be expected if an adequate decompression is achieved at surgery. The origin of non-radicular distribution arm pain or axial pain is much more difficult to determine. Non-radicular distribution pain may represent a referred phenomenon from the cervical spine. In isolated cases, in patients who have a combination of axial pain and radicular pain, focal neural decompression can sometimes alleviate or reduce axial pain. However, in many cases, the axial pain is not due to neural compression and does not respond to decom-pressive surgery. In selected cases, some believe that segmental fusion can be of benefit in the treatment of axial pain . These concepts are quite controversial and do not constitute clear indications for surgery in the neurosurgical literature. The treatment of axial pain with fusion surgery has been promoted by some and has been a concept considered more commonly by orthopedic surgeons.
After a determination of the extent of the degenerative disease has been made, the type of surgery required to achieve the objectives of surgery has to be formulated. A variety of factors influence the nature of the operative procedure, including the nature, location and extent of the pathology and patient factors. The surgeon must determine where the degenerative pathology is located in relation to the neural elements and how this is most directly and safely accessed. The patient's age, bone quality, spinal curvature and general health can influence the approach and extent of surgery required.
Decompressive surgery is typically a component of an operative procedure for cervical degenerative disease. Decompression of the spinal cord and/or nerve roots may be required in a given case. Access for decompression of either of these elements can be achieved by an anterior or a posterior approach. The initial techniques available for spinal cord and nerve root decompression involved a posterior approach by complete or partial laminectomy. These techniques involved a midline incision and retraction of the paraspinal musculature off the laminae and spinous processes. The laminae would be removed to expand the AP diameter of the cervical canal to decompress the spinal cord. If the nerve root requires decompression, a foraminotomy could be performed by extending the laminectomy lateral over the medial aspect of the given facet joint, which would overlie the intervertebral foramen. The foraminotomy could be performed alone or in combination with a midline laminectomy.
Long-term analysis and follow-up of patients who have undergone cervical laminectomies for stenosis and myelopathy have demonstrated that this technique is not universally applicable for all patients with stenosis. Some patients fail to improve, despite the intervention, or could experience a delayed deterioration following the intervention . The cause of myelopathy from stenosis is not only determined by the degree of the AP canal diameter narrowing. In some cases, anterior compression, especially in the presence of a straightened or kyphotic cervical spine or the presence of micro-motion, can contribute to myelopathy. These two factors are not directly addressed by a laminectomy (Fig. 31.5). The soft tissue dissection required to access the laminae and the subsequent bony resection can increase the degree of instability of the spine resulting from a laminectomy. The patient may experience further micro-trauma to the cord from the instability or develop a kyphotic deformity of the cervical spine, which can contribute to anterior compression of the spinal cord or predispose to a cervical pain syndrome . Based on these potential limitations of the laminectomy, supplementing the posterior decompression with fusion or effecting decompression by an anterior approach has been considered in certain cases .
Posterior cervical foraminotomy was the initial technique developed for cervical nerve root decompression. The posterior aspect of the intervertebral foramen is unroofed. Enlargement of the foramen by this technique, in some cases, is all that is required to effect decompression of the nerve root. Typically, the compressing pathology in foraminal stenosis is located anterior to the nerve root. In the case of a herniated disk, a soft fragment of disk can be
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