Cervical Spondylosis

Finally, as disk spaces narrow secondary to degeneration, the cervical spine shortens. This can produce infolding of the ligamentum flavum, which narrows the anteroposterior diameter of the spinal canal. The vertebral column shortens, but the length of the spinal cord remains unchanged, resulting in traction on the lower cervical nerve roots.

When spinal cord compression occurs, pathologic examination shows flattening and distortion of the cord. Several indentations may be present, depending on the number of spondylotic bars. Demyelination of the lateral and posterior columns and neuronal damage at the points of compression are the primary microscopic findings.

Clinical Manifestations. Cervical spondylotic radiculomyelopathy or myelopathy is the commonest myelopathy of later life. Its onset is usually insidious. Paresthesias of the hand may occur early, and the patient may experience numbness and tingling in a radicular distribution, as well as radicular pain. Weakness and atrophy in the upper extremities vary, depending on the spinal cord segments or nerve roots compressed. Because the fifth and sixth cervical segments are most frequently compressed, stretch reflexes of the biceps and triceps, respectively, may be diminished. In the lower extremities, a spastic paraparesis is common, but one leg may be more severely involved than the other. Vibration and position sense are often diminished in the feet. The gait is spastic and sometimes ataxic because of impaired position sense. Sphincter disturbances (especially urinary urgency, frequency, or retention) and sensory levels are seen only in later stages. The spastic paraparesis is insidious and slowly progressive in some cases and more acute in onset in others; muscle fasciculations, atrophy, and weakness of the upper extremities may develop in conjunction with it, sometimes simulating motor neuron disease when sensory or sphincter disturbances are absent.

Diagnosis. Spinal magnetic resonance imaging (MRI) or computed tomography (CT) myelography is required to establish the presence of spinal cord compression, confirm the cause, and exclude other pathologic processes. Narrowing of the anteroposterior sagittal diameter to 11 mm or less in any area of the cervical spine increases the risk of cord compression. Multilevel disease is common. Cerebrospinal fluid (CSF) is normal or shows a mild to moderately elevated protein content.

Treatment. Nonoperative treatment may involve analgesics and immobilization of the neck, for example, in a cervical collar. Although most nerve root syndromes subside spontaneously, spondylotic myelopathy, if progressive, requires surgical intervention. Some patients improve after surgery, but only stabilization can be realistically expected.

Spinal cord decompression may be done through either an anterior or a posterior approach, and it is not clear which approach is best. About 75% of patients stabilize or improve after surgery, whereas up to 25% may worsen or progress. There is no agreement on factors that predict the surgical outcome.

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