Degenerative Diseases of the Spine: Lecture on the Cervical Spine (Clinical Presentation)

Because cervical disc herniations may occur after significant degenerative change, patients present with a long history of neck pain. With herniation of the nuclear material, the patient's symptoms then change from neck pain to neck pain with additional arm symptoms. The upper extremity symptoms may include paresthesias, dysesthesias, pain, and weakness. Holding the arm elevated in a position of comfort is a classic finding of cervical disc herniation.

It is important to note by history and physical examination the specific nerve root level affected. At the C4–C5 disc level, for example, the fifth cervical root can be compressed by a disc herniation (see figure). Occasionally a patient may not have any symptoms referable to the neck and may present with painless weakness in the upper extremity or with myelopathy. (Spinal Cord Compression)

Diagnostic Evaluation
As with disc herniations elsewhere, plain radiographs are not particularly useful. There may be some changes indicative of a degenerative process at the affected level (e.g., disc space narrowing, spur formation, or subluxation).

Myelography in combination with CT scanning is more effective and sensitive than either test alone (see figure). The CT scan should be done with very thin slices, and sagittal reformations should be generated.

Diagnostic Evaluation
A few investigators have advocated the use of CT discography in the investigation of the herniated disc (see figure). However, injection of the contrast dye at a level in which there is significant cord compression can cause or exacerbate neurologic symptoms.

Diagnostic Evaluation
MR scanning is a primary investigative tool for herniated cervical disc disease (see figure). Very thin axial sections should be taken. Software is continually being developed with resultant improvement in the generated images. Unfortunately, cervical MRI requires the subject's head and face to be placed in a small, enclosed space, and the examination, particularly the T2–weighted images, may take 30 to 40 minutes to complete. Many patients who do not consider themselves claustrophobic have found this to be uncomfortable and anxiety producing. Some patients may require sedation before MR examination of the cervical spine. Patients with cardiac pacemaker should NOT undergo MRI.

Diagnostic Evaluation
In patients with upper extremity symptoms without objective findings of neurologic deficit, EMG examination may be of great value because it can be used to localize the symptomatic nerve root. Nerve conduction studies should also be done in these patients to detect concomitant peripheral nerve entrapment syndromes. However, EMG findings may be normal even in patients with very marked compressive cervical radiculopathy because the cervical sensory route may be selectively compromised. In addition, the EMG may be normal due to overlapping motor innervation of a single muscle.

Nonoperative Treatment
Many nonoperative modalities have been suggested for the treatment of herniated cervical disc disease, but most have not been subjected to scientific scrutiny. Immobilization, either by the use of an orthosis or by bed rest, has been widely used. Although it probably does not alter the natural history of the herniated cervical disc, it may cause some decrease in pain by limiting cervical motion and thus the irritation of a compressed root. Although traction has been advocated, its maximum benefit is for foraminal stenosis. There is no evidence that traction, either intermittent or continuous, affects herniated nuclear material in any way. In general, physical modalities are used to control symptoms rather than alter the natural history of this condition.

Operative Treatment
Surgical intervention is indicated when a cervical disc herniation causes spinal cord dysfunction, profound weakness in the upper extremity, or prolonged arm pain.

Two surgical approaches have been advocated–posterior and anterior. The posterior approach is best reserved for lateral herniations in patients who have primarily radicular symptoms.

The posterior approach usually consists of a hemilaminectomy with removal of part of the facet joint on one side. It allows good visualization of the nerve root (see figures below).

The anterior approach is ideal for bone spurs or when the herniation is central and when there are significant symptoms of neck pain in association with radicular or spinal cord symptoms. The anterior approach allows for complete disc excision and decompression of the spinal cord. The risk of neurologic injury at the time of elective anterior cervical disc excision is less than 1%. There is some controversy as to whether disc excision should always be accompanied by an anterior interbody fusion. Most surgeons agree that performing a fusion at the time of disc excision prevents the development of a kyphotic deformity and decreases the incidence of postoperative neck pain. Some surgeons advocate placing a metal plate with the bone graft to aid fusion.

Lecture Key Points
Most herniations are asymptomatic.

Other Key Points
Most symptomatic herniations can be managed nonoperatively. If a disc herniation causes significant neurologic deficit or unremitting, profound pain, surgery may be indicated.

MRI is the often best imaging modality for demonstrating herniated disc disease.