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Keywords
Cervical Stenosis
Cervical Spinal Stenosis
Cervical Myelopathy
Spinal Cord Injury

Definition
Cervical Spinal Stenosis is the narrowing of the cervical spinal canal. The narrowing may lead to pressure on the spinal cord and cervical spinal nerves.

Indications
The operations for cervical spinal stenosis are indicated for the relief of numb clumsy hands, arm or leg numbness, difficulty walking (gait disorder), bowel and bladder symptoms, incomplete paralysis, etc. The discovery of cervical spinal stenosis raises the question of surgery to prevent future deterioration versus the resolution of present symptoms.

Technical Considerations
The goal of surgery is to decompress the spinal cord. Different surgical options involve: anterior vs. posterior approaches, fusion vs. no fusion, instrumentation vs. no instrumentation.

Literature Review
Featured Review:
The natural history of cervial myelopathy (spinal cord pressure due to cervical stenosis) is varaible. Some authors have reviewed the natural history as "the course of disease may be very prolonged. Long periods of non-progressive disability are the rule, and a few progressively deteriorating courses exceptional." (ref #8) This view was endorsed by Nurick who viewed the disability of cervical myelopathy due to cervical stenosis as established early with little deterioration over time.(ref #4, ref #5) Other authors have reviewed patient groups with cervical myelopathy and found 36% improvement in a non-operated group and 64% not improved.(ref #1) In the non-improvement group, 26% deteriorated clinically over time.(ref #1) Perhaps the most clearly defined series is depicted in the table below. (ref #9)

In addition, this study did not demonstrate patients who improved once symptoms started.(ref #9) 67% of patients in one series had a progressive downhill course rather than the episodes described above. (ref #6)
Measuring the degree of disability in patients with cervical myelopathy describes the range from complete paralysis to very subtle symptoms that may interfere minimally in patients' lives. Since patients with cervical myelopathy due to cervical stenosis may have symptoms in the arms, legs and bowel and bladder, different degrees of disability related to these areas form the grading systems. One system of evaluation concentrated on the ability to walk but a more comprehensive system involved all the extremity functions and bowel and bladder. (ref #5, ref #2) The duration of symptoms and the degree of symptoms are important considerations in surgery for cervical myelopathy (spinal cord injury) due to cervical stenosis.
Classification of patients into defined spinal cord syndromes is sometimes achievable. A method of classification is listed in the table below. (ref #7)

As in other areas of clinical medicine the patient's history is important: progression of symptoms may occur before the doctor can find changes in the physical exam of the patient.

Complications
The potential complications of surgery for cervical myelopathy due to cervical spinal stenosis depends on the surgical approach and the nature of the operation. In general, the common risks are death, paralysis, spinal cord injury, failure to improve, nerve root injury, spinal fluid leak, and wound problems. Specific operations may produce risks related to approach (hoarseness, difficulty swallowing) or problems related to bone grafts (non-union, bone graft malposition) or due to instrumentation (hardware failure)

Author’s Comment
Cervical Spinal Stenosis leading to Cervical Myelopathy is a complex problem. Progressive symptoms should be interrupted. Many surgical series show clinical improvement but there is a persistent percentage of patients who do not improve with intervention. In the end, the patient and surgeon are depending on the biological reversability of partial spinal cord injury. How long the spinal cord has been under pressure and the degree of injury produced by the pressure are the logical factors determining the potential to reverse the "spinal cord injury."

References
1. Epstein, J.E., W., The surgical management of cervical spinal stenosis, spondylosis, and myeloradiculopathy by means of the posterior approach., in Cervcial Spine Research Society: The Cervical Spine. 2nd ed. 1989, J.B. Lippincott Co.: Philadelphia.
2. Hukuda, S., Operations for cervical spondylotic myelopathy. J.B.J.S. (Br), 1985. 67: p. 609-615.
3. Phillips, D., Surgical treatment of myelopathy with cervical spndylosis. J Neurol. Neurosurg. Psychiatry, 1973. 36: p. 879-884.
4. Nurick, S., The pathogenesis of the spinal cord disorder associated with cervcial spondylosis. Brain, 1972(95): p. 87-100.
5. Nurick, S., The natural history and the results of surgical treatment of the spinal cord disorder associated with cervical spondylosis. Brain, 1972(95): p. 101-108.
6. Symon, L.L., P., The surgical treatment of cervical spondylotic myelopathy. Neurology, 1967. 17: p. 117-127.
7. Crandall, P.B., U., Cervical spondylotic myelopathy. J. Neurosur, 1966. 25: p. 57-66.
8. Lees, F.T., J., Natural history and prognosis of cervical spondylosis. BMJ, 1963(2): p. 1607-1610.
9. Clark, E.R., P., Cervical myelopathy: A complication of cervical spondylosis. Brain, 1956(79): p. 483.