With regards to spinal disorders, neck pain is one of the most common presenting symptoms, only second to low back pain. When pain radiates down the arm and is associated with sensory and motor disturbances, cervical radiculopathy is suspected.
With regards to spinal disorders, neck pain is one of the most common presenting symptoms, only second to low back pain. It is more often spontaneous in onset without having a specific inciting event. When pain radiates down the arm and is associated with sensory and motor disturbances, cervical radiculopathy is suspected. Cervical radiculopathy occurs when a nerve root is compressed or irritated, causing associated sensory, motor, or reflex changes in the affected nerve root distribution. It is a substantial cause of disability and morbidity and occurs in both genders, typically during the middle ages.
Epidemiology
A population-based study from Rochester, Minn., found the annual age-adjusted incidence of cervical radiculopathy to be 83 cases per 100,000 persons. The annual incidence rate was higher for men, with a rate of 107 cases per 100,000 persons for men and 63 cases per 100,000 persons for women. The ages ranged from 13 to 91 years, with the peak incidence occurring at 50 to 54 years of age in both genders. In this study, either spondylosis, disk protrusion, or both were involved in nearly 70% of the cases.
Anatomy
There are a total of 8 cervical nerve roots, each exiting above the vertebrae of the same numeric designation, with the exception of C8, which exits above the T1 vertebrae. The neural foramina through the nerve roots exit are bordered anteromedially by the uncovertebral joint, posterolaterally by the facet joint, superiorly by the pedicle of the vertebral body above, and inferiorly by the pedicle of the vertebral body below. For example, the C6 nerve root exits through the C5-C6 neural foramen formed by the C5 and C6 vertebral bodies and disk.
Anatomy
There are a total of 8 cervical nerve roots, each exiting above the vertebrae of the same numeric designation, with the exception of C8, which exits above the T1 vertebrae. The neural foramina through the nerve roots exit are bordered anteromedially by the uncovertebral joint, posterolaterally by the facet joint, superiorly by the pedicle of the vertebral body above, and inferiorly by the pedicle of the vertebral body below. For example, the C6 nerve root exits through the C5-C6 neural foramen formed by the C5 and C6 vertebral bodies and disk.
Pathophysiology
The three most common ways that compress or irritate an exiting nerve root include: herniation of a disc posterolaterally, degeneration of a disc causing decreased height of the neural foramen, and cervical spondylosis, which can occur at the vertebral body, uncovertebral joint, or facet joint. Cervical degenerative changes have been shown to occur in those over 40 years old. The progressive loss of the disc’s viscoelastic properties can lead to loss of disc height and vertebral end plate stress. As a result, osteophytes are formed, which serve to increase the overall surface area and counterbalance the increased stress. This decrease in disc height can also cause increased joint stress, leading to hypertrophy of the uncovertebral and facet joints as arthritic changes occur. Both formation of osteophytes and hypertrophied joints, known collectively as cervical spondylosis, can contribute to an obstructive occlusion of the neural foramen leading to impingement. With regards to disc herniations, the posterior longitudinal ligament is oftentimes weaker than its anterior counterpart and thus, with excess pressure applied to the cervical disc, a herniation can occur posteriorly. When this herniation is broad enough or extends laterally into the intervertebral foramen, an occlusion may occur.
The exact pathogenesis of radicular pain remains unclear, but it is thought that compression alone may not always be enough to cause pain, and that an inflammatory chemical component is needed. It has been found that chemical mediators involved in the inflammatory process are released from sensory neurons and intervertebral disc tissues, contributing to the occurrence of pain. Further studies have found that compression of the dorsal root ganglion alone can cause an inflammatory response by causing prolonged cell body discharges. In addition, increased permeability of the membrane of the dorsal root ganglion with respects to its surrounding nerve root membrane is also hypothesized to be a potential source for radicular pain.
Compromise of the neural foramen resulting in impingement of the exiting nerve root may also result in impairment of the blood supply to the nerve itself. Radicular arteries within the dural root sleeve as well as venous flow may be inhibited, causing spasm and ultimately decreased perfusion to the nerve. Insult to the nerve root also can result in increased permeability of the intrinsic blood vessels, causing edema to occur within the nerve root itself. This chronic edema and fibrosis can eventually increase the nerve’s membrane threshold and increase sensitivity to pain.
Overall, in the younger population, cervical radiculopathy is often attributed to a disc herniation or an acute injury causing foraminal stenosis. Cervical spondylosis contributing to foraminal narrowing is usually observed in an older population. One study showed that in 70% to 75% of cases, foraminal encroachment was responsible for cervical radiculopathy versus 20% to 25% of cases due to disk herniation. The C7 nerve root is the most commonly affected followed by C6, C8, and C5 in descending order of incidence.
Clinical presentation
Patients typically present with neck pain radiating to the upper extremity. The distribution of the radiating pain depends on the cervical levels that are involved. Typically, pain is distributed in a myotomal pattern but can also involve surrounding areas, including the suboccipital, scapular, and, rarely, chest wall regions. Sensory symptoms such as numbness and tingling usually occur in a dermatomal pattern. A subset of patients will present with weakness alone without any significant pain or sensory symptoms. In this case, proper investigation is needed to assess whether an alternative diagnosis is present, including the presence of a myelopathy. Cervical myelopathy may present with deficits such as decreased sensation in the hands or fine motor skills, as well as poor balance and bowel and bladder dysfunction. The latter deficits are typically not found in cervical radiculopathy and should be investigated thoroughly. The timing of the presenting symptoms may also help distinguish the pathologic etiology. An acute or subacute presentation may be related to a disc herniation, whereas a slow and insidious presentation may be due to cervical spondylosis.
Physical examination
Observation of the patient’s movements specific to the cervical spine as well as generalized movements such as gait and posture will help fully assess the patient. Detection of muscle atrophy in the shoulder girdle and upper extremities should be noted. Palpation of the cervical spine and surrounding muscles will help detect any deformities such as loss of lordosis, tenderness, or muscle spasms. Cervical spine range of motion should be fully assessed to determine limitations. In addition, lateral rotation or bending towards the affected side may occlude the neural foramen and reproduce symptoms.
Assessment for weakness, sensory changes, and diminished reflexes is useful for the detection and isolation of the nerve roots involved in a cervical radiculopathy ( Table 1 ). Profound myotomal weakness is rare, as most muscles have innervations from at least 2 nerve roots. Consideration for polyneuropathy including polyradiculopathy or brachial plexopathy should be given. Dermatomal changes will typically be found in the distal dermatome distribution. Gait and lower extremity strength testing can help determine whether a myelopathy is present. Also, upper motor neuron signs should be documented, including Hoffman sign, hyper-reflexia, Babinski response, and clonus. Provocative maneuvers can also be performed. Both Spurling and Scoville described a provocative maneuver in which the patient’s head was rotated toward the suspected side and, with applied downward pressure; the head was laterally bent towards that side. A positive test occurs with reproduction of the patient’s radicular symptoms. The Spurling test has been shown to have a specificity of 93% and sensitivity of 30% in detecting cervical radiculopathy, indicating its use as a confirmative examination and not necessarily for screening. Other tests that can be conducted include the shoulder abduction test, neck distraction test, and Valsalva maneuver test, all of which have less accuracy and reliability.
| Nerve Root | Pain Distribution | Motor | Sensory | Reflex |
|---|---|---|---|---|
| C4 | Lower neck, trapezius | None | Cape distribution (lower neck and shoulder girdle) | None |
| C5 | Neck, medial scapula, shoulder, lateral arm | Shoulder abduction, elbow flexion | Lateral upper arm | Biceps |
| C6 | Neck, lateral forearm, first and second digit | Elbow flexion, wrist extension | Lateral forearm, first and second digit | Brachioradialis |
| C7 | Neck, medial scapula, dorsal forearm, third digit | Elbow extension, wrist flexion | Dorsal forearm, third digit | Triceps |
| C8 | Neck, medial forearm, fifth digit | Finger flexors, finger abduction and adduction | Medial forearm, fourth and fifth digit | None |
Related posts:
History, Physical Examination, and Differential Diagnosis of Neck Pain
The Anatomy and Pathophysiology of Neck Pain
Evaluation of the Patient with Neck Versus Shoulder Pain
Conservative Treatment for Neck Pain: Medications, Physical Therapy, and Exercise
Thoracic Outlet Syndrome
Neck Pain from a Spine Surgeon’s Perspective
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