Definition

The term cervical degenerative disease encompasses a wide range of pathologic changes affecting all the components of the cervical spine that may lead to axial or radicular pain.

The mechanisms underlying cervical degenerative disease are complex and multifactorial. Genetics, aging, and attrition and trauma may all play an important role. It is believed that disc degeneration results in altered, abnormal load distribution, which in turn leads to a cascade of structural changes that affect the various components of the spinal column. These structural changes may change spinal posture and stability and may compromise neural function. The pathomechanisms underlying axial and radicular pain are still not completely clear. Increased vascularization after discal herniation and the presence of inflammatory mediators such as nitric oxide, prostaglandin E₂, interleukin-6, matrix metalloproteinase, and others play an important role in the pathogenesis of pain [1].

In the seventh and eighth decades of life, most if not all individuals display diffuse degenerative changes throughout the cervical spine. Only a fraction of these individuals, however, have clinical signs and symptoms. Not uncommonly, individuals who are symptomatic early on become asymptomatic as the degenerative process evolves.

The lowest five cervical vertebrae are connected by five structural elements: the intervertebral disc, the facet joints, and the neurocentral joints (joints of Luschka) [2]. The neurocentral joints are unique to the cervical spine and do not appear anywhere else in the spinal column. These joints, located in the posterolateral aspect of the vertebral bodies, consist of bone projections that articulate with the vertebral body above them (Fig. 3.1). They provide some stability to the very mobile cervical spine and protect the exiting nerve roots from pure lateral disc herniations. Once the disc degenerates, however, these joints may hypertrophy, narrow the intervertebral foramina, and modify their shape, thus compromising the radicular nerves or the dorsal root ganglia. A similar degenerative process may involve the facet joints that are posteriorly located, and they in turn may compress the exiting neural elements from the back. Indeed, the most common cause of cervical radiculopathy is foraminal narrowing due to facet or neurocentral joint hypertrophy [3]. The lower cervical spine, especially C4-C5, C5-C6, and to a lesser extent C6-C7, is the source of pain in most symptomatic individuals. Unlike in the lumbar spine, nucleus pulposus herniation is less frequent and is the cause of radicular pain in only 20% to 25% of cases [3,4]. As the spinal cord occupies a substantial proportion of the cervical spinal canal, posteriorly directed herniations can result in significant cord compression as well as radicular symptoms.

Symptoms

The most common symptom, one that drives most of the patients to the physician’s office, is pain. In the general population, the point prevalence for neck pain ranges between 9.5% and 22%, whereas lifetime prevalence may be as high as 66%. The annual incidence is higher in men and peaks around 50 to 54 years of age [5,6].

In this respect, two large groups of patients can be recognized: patients whose main complaint is limited to axial pain and patients with radicular pain. Patients with axial pain typically complain of stiffness and pain in the cervical spine. The pain is usually more severe in the upright position and relieved only with bed rest. Cervical motion, especially hyperextension and side bending, increases the pain. In patients with pathologic changes involving the upper cervical joints or degeneration of upper cervical discs, the pain may radiate into the head, typically into the occipital region. In patients with lower cervical disease, the pain radiates into the region of the superior trapezius or the interscapular region. On occasion, patients present with atypical symptoms, such as jaw pain or chest pain–cervical angina.

Identification of the pain generator and its management are far more challenging in patients with axial pain because imaging studies frequently show multilevel pathologic changes, such as multilevel disc degeneration, facet arthropathy, and uncovertebral joint disease. It is often difficult and quite challenging to identify the exact source of pain. As the facets and the uncovertebral joints, peripheral discs, and ligaments all contain nerve endings, each one or a combination of them could be the source of pain [4].

Patients with radicular pain have symptoms commensurate with the involved nerve root. The pain usually follows a myotomal distribution and is frequently described as boring, aching, deep-seated pain. The pain is made worse by tilting the head toward the affected side or by hyperextension and side bending. Infrequently, patients find that the pain may be made more tolerable when the hand of the symptomatic side is placed over the top of the head (shoulder abduction release) [7]. The sensory symptoms (numbness, tingling, and burning sensation) usually follow the dermatomal distribution. When carpal tunnel syndrome accompanies cervical radiculopathy (double crush syndrome), the sensory changes may be in median nerve distribution. Indeed, there is a high concurrent incidence of cervical radiculopathy and carpal tunnel syndrome [8]. Sclerotomal pain, frequently overlooked or interpreted as trigger points, may be present and commonly resides in the medial or lateral scapular borders [9,10]. On occasion, patients complain of arm or hand weakness as they may drop things or find difficulty with routine activities of daily living.

Physical Examination

Because of severe axial pain, the patient may keep the head and neck immobile as cervical movements may increase the symptoms. Frequently, the only comfortable position is when the patient reclines and the neck is unloaded. Axial pain may increase with cervical extension or side bending. The Spurling test, whereby simultaneous axial loading and tilting of the head toward the symptomatic side in the upright position are performed, elicits neck and radicular pain. This test may elicit a specific dermatomal pain pattern and has high specificity and sensitivity of 95% for identifying nerve root compression [11]. Manual neck distraction may alleviate the symptoms. Tender spots are frequently found over the cervical paraspinal muscles, within the superior trapezius muscles, or in muscles supplied by the compromised root. These spots refer to areas within the muscles that, when stimulated, elicit a sensation of local pain [10]. Tender spots may be of diagnostic significance, especially when they are found unilaterally or in conjunction with other symptoms of cervical radiculopathy.

In patients with radicular pain, depending on the root involved, examination may reveal weakness in myotomal distribution, sensory changes in dermatomal distribution, and reflex changes (Table 3.1). Meticulous physical examination helps identify the compromised root: C5 root compromise will affect shoulder abductors; C6, elbow flexors; C7, elbow extensors; and C8, finger flexors. Finding of concomitant sensory and reflex changes is helpful. Dermatomal arrangement is not fixed and may vary in different patients because of aberrant rootlets or anastomoses between peripheral nerves. Frequently, dermatomes represent only a portion of the root’s domain [12]. The dermatomal charts are useful, however, and play a role in the patient’s diagnosis. Radicular pain frequently occurs without weakness, reflex, or apparent sensory changes. The most frequently affected roots are C5, C6, and C7 [3,6