Anatomy

Seven cervical vertebrae make up the bony elements of the cervical spine. A typical cervical vertebra is similar to other vertebrae in that it is composed of a body and a neural arch (Fig. 3-1). The neural arch is composed of two pedicles that form the sides and two laminae that meet in the midline to form the roof. Projecting dorsally where the laminae meet is the spinous process, and projecting laterally from the junction of the pedicle and lamina is a transverse process on each side. Two articular processes, the superior and inferior, project upward and downward, respectively, from the junction of the pedicle and laminae on each side and articulate with similar processes on adjacent vertebrae to form the zygapophyseal or facet joints.

FIG. 3-1 A typical cervical vertebra: S, Spinous process; L, lamina; A, articular facet; P, pedicle; T, transverse process; B, body.

The first two cervical vertebrae are atypical in that C1, the atlas, has no body (Fig. 3-2). Its body is attached to C2, the axis, and forms the dens, or odontoid process. This arrangement allows for most of the rotation in the cervical spine. Strong ligaments bind C1 to C2, the most important of which is the transverse ligament. The seventh cervical vertebra, vertebra prominens, is also somewhat atypical in that it has a long spinous process that is easily palpable beneath the skin. (Patients sometimes misinterpret this bony prominence and its overlying soft tissue as a “mass.”)

FIG. 3-2 A, The axis. B, The atlas and transverse ligament (T). C, The articulation of the atlas and the axis.

Several major ligaments stabilize the cervical spine (Fig. 3-3). The anterior and posterior longitudinal ligaments are applied to the respective surfaces of the vertebral bodies. The posterior longitudinal ligament tends to be somewhat weak laterally where it crosses the disc, thus forming a point where disc herniation may occur. Some gliding motion is allowed to occur between vertebrae by relatively weak capsular ligaments that bind together each articular joint. The ligamentum flavum, or yellow ligament, is situated between adjacent laminae, and in the cervical spine, extremely strong ligaments—the nuchal ligament and interspinous ligaments—provide posterior support.

FIG. 3-3 Ligaments of the cervical spine: anterior longitudinal ligament (A); posterior longitudinal ligament (P); nuchal ligament (N); interspinous ligament (I).

The vertebrae are separated from each other by the intervertebral discs, which constitute approximately one fourth of the length of the vertebral column. Each disc is composed of an inner nucleus pulposus, which is mainly gelatinous, and an outer layer, the anulus fibrosus, which is mainly fibrous. The discs distribute stress over a wide area of the vertebrae, absorb shock, and allow mobility. The nucleus pulposus has a very high water content in early life, but with age this tends to diminish. With this loss of water, abnormal pressures begin to be exerted on the anulus, which may lead to herniation and/or disc degeneration. Pathologic changes in adjacent structures (facet joint arthritis or osteophyte formation) may eventually develop as well.

Eight pairs of nerve roots arise from the cervical spinal cord. Each nerve exits above the vertebra of the same number. Thus, the sixth nerve root exits at the C5–C6 disc space. Each nerve, except the first two pairs, leaves the spinal column by passing through an intervertebral foramen (Fig. 3-4). Each foramen has as its superior and inferior boundaries the pedicles of the adjacent vertebrae. Posterolaterally, it is bounded by the apophyseal joint and, anteromedially, by the so-called joint of Luschka. In the cervical spine, this foramen is quite small and is almost entirely occupied by the nerve root. Thus, anything that compromises this space, such as disc degeneration with spur formation, could cause pressure on the nerve root.

FIG. 3-4 The intervertebral foramen. Note the proximity of the joint of Luschka (L). The nerve root exits this foramen. Compression of the root may occur with disc herniation or from degeneration with collapse of the disc, narrowing of the foramen combined with ingrowth of osteophytes from the facet joint and disc.

Examination

Examination of the neck begins with observation of the posture of the head and neck in relation to the torso. Any decrease in the normal cervical lordosis is noted. The neck is gently palpated for tender areas and trigger points. The range of motion of the cervical spine is then measured, and any movement that reproduces pain is noted. Flexion, extension, right and left bending, and right and left rotation are all recorded. A complete neurologic examination, including muscle strength testing, is always performed. The peripheral nerves are percussed for tenderness and tested for function. In addition, the shoulders and elbows are always carefully examined, particularly if there is any radiation of the pain or numbness and tingling.

Roentgenographic Anatomy

The examination of all neck disorders should include a standard roentgenographic evaluation. The roentgenographic features of the cervical spine are well visualized by the following: (1) anteroposterior view (Fig. 3-5); (2) lateral views in flexion and extension; (3) oblique views in both directions to visualize the intervertebral foramen (Fig. 3-6); and (4) an open-mouth odontoid view to visualize the odontoid process and the relationship between C1 and C2.

FIG. 3-5 Anteroposterior (A) and lateral (B) views of the cervical spine. S, Spinous process; T, transverse process; B, body; A, articular (zygapophyseal) facet joint; P, pedicle; L, lamina. Note the slight lordosis and even spacing of the vertebrae and discs.

FIG. 3-6 Oblique view. S, Spinous process; F, intervertebral foramen; J, joint of Luschka; L, lamina; P, pedicle; A, articular facet joint; B, body.

Cervical Disc Syndromes

Disease of the cervical spine as a result of disorders of the disc will affect 50% of the population at some time, usually patients between the ages of 30 and 60. More than 90% of disc lesions in the cervical spine occur at the C5 and C6 levels, those being the most mobile segments. As disc degeneration occurs, two types of lesions result that produce very similar symptoms. The first of these is the soft disc protrusion or nuclear herniation. With this lesion, most common in the younger patient, a mass of nucleus pulposus begins to bulge outward, usually posterolaterally, at the area of the greatest weakness in the anulus fibrosus (Fig. 3-7). With severe disc protrusion, compression of the nerve root may occur, resulting in arm symptoms and radicular pain. Less severe herniation may produce only referred or axial spine pain, usually one-sided.

FIG. 3-7 Disc herniation (arrow) causing nerve root compression. Spur formation may occur in the same area.

The second, more common lesion results from chronic disc degeneration with subsequent settling or narrowing of the disc space and alterations in the surrounding structures including the facet joints. This is the so-called hard disc lesion, or cervical “spondylosis,” and occurs primarily in older age groups. As narrowing and collapse of the disc proceed, the vertebrae become more closely approximated, which leads to spur formation along the disc edges and at the joints of Luschka. Mild subluxation of the facet joints may also occur. All of these changes decrease the size of the intervertebral foramen, which may result in pressure on the nerve root. Inflammation and swelling may develop in conjunction with osteophyte formation, which further contributes to the narrowing of the foramen and nerve root compression.

Rarely, large posterior osteophytes along with degenerative narrowing of the bony canal may cause pressure on the spinal cord and produce mixed symptoms of upper extremity nerve root pain and lower extremity weakness. This is commonly termed cervical spondylosis with myelopathy. It is the most common cause of spastic paraparesis in the adult. In many of these cases, the lower extremity symptoms are much more disabling than the neck symptoms, a situation that can cause some initial confusion in determining their etiology.

CLINICAL FEATURES

Disc disease can produce several overlapping syndromes in the cervical spine: (1) axial or referred spine pain, (2) radicular arm symptoms from nerve root compression and, rarely, (3) cord compression symptoms.

Pain associated with disc disease usually develops gradually. Degeneration or slow herniation may initially cause only neck and referred pain, which often begins in the interscapular area and may be mistaken for a shoulder disorder. It is almost always unilateral. Patients may complain of a tightness or stiffness in the neck that worsens with activity. Morning stiffness is common, and certain movements, especially extension, exacerbate the pain. Looking backward over the shoulder of the affected side may also intensify the pain. In rare cases, pain in the anterior aspect of the chest (“cervical angina”) or breast may be the presenting complaint. Coughing, sneezing, and straining can accentuate the pain. If nerve root irritation or compression develops, pain may radiate into the shoulder and arm and along the radial aspect of the forearm (Fig. 3-8). Numbness and tingling are often noted in these same areas, and referred pain, which does not follow a dermatome pattern, is common along the upper medial border of the scapula. Headaches are not uncommon, and dysphagia has even been reported secondary to large anterior osteophytes. Headache or jaw pain may be present with high disc lesions. Patients with radicular pain sometimes find relief of the nerve root tension by abducting their arm and resting the forearm on the top of the head.

FIG. 3-8 Volar and dorsal dermatome pattern of the forearm and hand. Pain and paresthesias may radiate into these areas when the affected nerve root is compressed. NOTE: Extremity symptoms caused by disc disease are almost always unilateral.

Examination frequently reveals a decreased range of motion. Pain on hyperextension and local tenderness in the cervical spine are often observed. Trigger point tenderness is commonly noted in the area of referred pain in the interscapular region. (This pain is often reproduced by specific neck movements, usually extension with rotation to the involved side.) Pressure against the top of the head also may reproduce the pain in the arm (Fig. 3-9). Some sensory changes are occasionally present along the specific dermatome, but the sensory examination is frequently not very helpful. Motor weakness and reflex changes may be noted (Table 3-1).

FIG. 3-9 Vertex compression test. Pressure downward on the head with extension and tilting the head to the affected side may narrow the neural foramen and reproduce neck and/or arm pain when disc herniation or spondylosis is present.

Table 3-1 Clinical Features of Common Cervical Disc Syndromes

Spondylosis in the cervical spine may occasionally produce symptoms referable to the lower extremities (cervical spondylotic myelopathy). These symptoms occur as a result of pressure of posterior osteophytes on the anterior portion of the cervical spinal cord. The symptom complex may appear as a combination of cervical root and cord symptoms, but commonly, cord symptoms predominate. The patient may have a typical disc syndrome in the upper extremities, but in addition, gait difficulties, weakness, and spasticity may be present in the lower extremities. The lower extremity symptoms have a gradual onset at about 50 years of age and progress slowly. They are often more disabling than the neck symptoms, which are usually mild. The leg weakness is most severe in the proximal muscles. Bowel and bladder changes are rare. (Many patients with myelopathy may not appreciate their weakness because the changes in gait and balance are subtle.) Physical findings are those of an upper motor neuron lesion with hyperreflexia, clonus, and pathologic reflexes.

SPECIAL STUDIES

In most cases, the diagnosis is clear without further testing. Neck, interscapular, and/or arm pain that is aggravated by neck motion is typical. Eventually, however, the following studies may be needed:

1 Plain roentgenograms are usually performed first. Anteroposterior and lateral views are sufficient. They are usually normal in soft disc rupture. With chronic degenerative disc disease, however, there is loss of the height of the disc space with anterior and posterior osteophyte formation. Encroachment on the intervertebral foramen by osteophytes is noted on oblique films (Fig. 3-10).

2 Myelography, sometimes followed by computed tomography (CT), remains useful in the evaluation of cervical radiculopathy, although with the development of magnetic resonance imaging (MRI), it is less commonly used. It is helpful in localizing the lesion but is not without some morbidity and is indicated only under two circumstances: (1) if surgical intervention is contemplated, or (2) if other serious spinal abnormality is suspected. Loss of the normal root “sleeve” and indentation of the dural sac are often seen (Fig. 3-11). Spinal fluid analysis performed at the time of myelography may show a slight increase in protein content.

3 MRI is also valuable in the assessment of the cervical spine and is more commonly used than myelography. It is attractive partly because it is noninvasive and uses no ionizing radiation. It should be used selectively because of its continuing high cost. Many patients are excluded from this modality for various reasons: obesity, the presence of pacemakers, internal fixation devices, and claustrophobia, among others (although newer “open” models cause less claustrophobia). The examination time is also quite lengthy. Indications for its use are generally the same as those for myelography. Like myelography, magnetic resonance imaging is usually indicated later in the disorder, after several weeks have passed without recovery. CT scanning, although less expensive, is not as helpful in evaluating degenerative disc disease in the cervical spine as it is in the assessment of traumatic conditions of the neck.

4 Electromyography can confirm the diagnosis in some cases if the disorder has caused nerve root compression long enough. It can also differentiate neurologic from muscular conditions. Nerve conduction studies help rule out peripheral nerve disorders.

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