By D. James Sceats, MD
Cervical spondylosis is the process of age related degeneration of the neck bones. As the spine ages, the cartilage on the end of the vertebrae wear out and shrink, causing the bones to get closer together, and allowing them to rub against one another. This process of rubbing each other stimulates the bones to lay down more bone, similar to what happens in the finger bones with arthritis. In the same fashion as arthritis elsewhere, the more a joint is used, the faster arthritis develops. Heavy lifting loads the neck and accelerates the normal wear and tear.
Just as arthritis of the fingers makes the joints bigger, cervical spondylosis involves the formation of bone spurs. These spurs can narrow the holes in the spine, called foramena, where the nerve roots exit, causing radiculopathy, or the spinal canal itself. If the spinal canal is narrowed enough that the spinal cord is significantly compressed, a different problem may exist, myelopathy. Some people can have a combination of the two, called a myeloradiculopathy.
The arthritis itself causes a stiff, painful neck. Pinching of one of the individual nerve roots can cause arm pain, tingling, weakness or numbness. Compression of the C6 nerve root can sometimes be confused with carpal tunnel syndrome. Symptoms of myelopathy include uncoordination, difficulty walking, increased reflexes, loss of bowel or bladder control, numbness and weakness in the arms and legs.
Diagnosing cervical spondylosis is readily done with plain radiographs of the neck. However, these are not adequate for planning surgical intervention. Correlating the results of a thorough neurological examination with the results of an MRI scan of the cervical spine allows a neurological surgeon the best opportunity to determine if surgical intervention is required, and the most appropriate treatment. Sometimes a myelogram followed by a CT scan is needed if an MRI does not provide enough information. An EMG (electromyogram) may also assist in making the proper diagnosis.
Not all patients that have radiographic evidence of cervical spondylosis and have a radiculopathy or myelopathy are in fact symptomatic from their degenerative changes. There are other diseases that may mimic the symptoms of cervical spondylosis such as amyotrophic lateral sclerosis, a spinal cord tumor, B12 deficiency, syringomyelia, vascular malformations, radiation induced myelopathy, a brachial plexus lesion, a peripheral neuropathy, or a demyelinating disease. Obviously, it is very important to make the correct diagnosis in order to obtain the best results from surgery.
Surgery is best reserved for progressive neurological deficits, avoiding surgical intervention for neck pain alone, as this is best treated conservatively. Despite significant narrowing of the spinal canal, some patients have surprisingly few signs or symptoms of their stenosis. They are often followed with regular neurological examinations to determine if they are developing neurological deficits. If your surgeon has determined that your symptoms are severe enough to warrant surgical intervention, then the decision will be made on the best approach for you.
Posterior approaches (from the back of the neck) are often used if multiple levels are involved, and the normal lordotic curvature of the spine is preserved. Posterior decompression has traditionally involved removing the lamina and spinous processes, called a laminectomy. This is often combined with instrumentation and bone placement to achieve a fusion, or arthrodesis. At some institutions, the spinal canal is enlarged posteriorly, but much of the lamina is preserved in a procedure called a laminoplasty.
Anterior approaches (from the front of the neck) are more common than posterior ones. In an anterior surgery, the disc between two vertebrae is removed as well as the bone spurs, and some type of spacer is placed where the disc was, to maintain disc height and facilitate a fusion. Often a plate is attached to the front of the spine to improve the likelihood of fusion. Anterior approaches are required if the normal lordosis is lost and a kyphosis, or forward curvature of the spine exists. Rarely, one or more vertebral bodies must be removed to provide for a complete decompression of the spinal cord. Instrumentation has been developed to replace a cervical disc, but only a single level can be addressed in this fashion.
Changing the mechanics of the neck by a fusion, done either anteriorly or posteriorly, does increase the rate of degeneration of discs above and below the fusion. It is for this reason that surgery for neck pain alone is in general not recommended. Cervical surgery for stenosis is usually quite successful, however some complications can occur. Myelopathy responds less well to decompression than radiculopathy. Either approach has a small, but real risk of increased neurological deficit, and also failure of fusion. Anterior approaches may be accompanied by carotid or vertebral artery injuries, hoarseness, esophageal injury, airway obstruction or graft migration. The posterior approach has fewer inherent risks, because fewer vital structures are encountered, but it is significantly more painful because of the greater amount of muscle dissection required.
If you are concerned about numbness, weakness or balance troubles, you should schedule a visit with your physician to discuss these symptoms.