Laboratory Studies
See the list below:
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Consider performing rheumatologic workup to evaluate for possible rheumatoid arthritis, ankylosing spondylitis, Reiter syndrome, and polymyalgia rheumatica. These tests include the following:
Rheumatoid factor (elevated in rheumatoid arthritis)
HLA-B27 (positive in ankylosing spondylitis)
Erythrocyte sedimentation rate (elevated in polymyalgia rheumatica)
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Consider performing infection workup to evaluate for possible discitis, epidural abscess, and vertebral osteomyelitis, including the following tests:
White blood cell count with differential (elevated with a left shift in bacterial infection)
Blood cultures (positive for the infecting organism)
Erythrocyte sedimentation rate (elevated in infection, but may be a nonspecific finding)
Imaging Studies
Imaging studies evaluate anatomy rather than function and are prone to false positive and negative results. For example, Boden et al's cervical MR study cites abnormalities in nearly 20% of asymptomatic subjects. [28] In a study by Kuijper et al, clinically significant root compression was found in 73% of patients on MR, whereas in 45% of patients, root compression was found that could not be clinically correlated. [29] Consequently, results of imaging studies must be interpreted within the context of each clinical case, as false-positives and false-negative MRI findings occur rather frequently.
Plain radiographs
See the list below:
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Plain cervical spine radiographs are used to evaluate chronic degenerative changes, metastatic disease, infection, spinal deformity, and stability.
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Cervical spine trauma films use 7 views, including anteroposterior (AP), lateral, bilateral oblique, open-mouth, flexion, and extension.
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Flexion-extension views identify subluxations or cervical spine instability.
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Open-mouth views evaluate the odontoid process and C1-C2 stability.
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AP views identify tumors, osteophytes, and fractures.
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Lateral views assess stability and spondylosis (ie, spurring, disc space narrowing).
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Oblique views reveal DDD, as well as foraminal encroachment by uncovertebral or Z-joint osteophytes.
A study by van Eerd et al indicated that although, in patients suspected of having degenerative cervical facet joint pain, these joints cannot be judged via standard cervical radiographs owing to the joints’ superposition, clinical use can be made of other, generally accepted radiologic features of degeneration, including disc height loss, anterior vertebral osteophytes, posterior vertebral osteophytes, vertebral endplate sclerosis, and uncovertebral osteoarthritis. According to the investigators, substantial interrater agreement was achieved using these characteristics. Moreover, agreement with CT scan analysis was found with regard to cervical disc height loss when, using radiographs, such loss was qualitatively defined as a cervical disc height that can fit “more than 3 times into the posterior vertebral body height of the vertebra below.” [30]
CT scanning
See the list below:
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See the image below.
Postdiscography axial computed tomography (CT) scan demonstrating right posterolateral subligamentous protrusion.
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CT scans delineate cervical spine fracture and are used extensively in trauma cases.
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Helical or spiral CT scanning generates an infinite number of images after data acquisition, providing more information for detailed fracture evaluation than does conventional CT scanning
CT myelography
See the list below:
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A myelogram followed by a CT scan may be obtained prior to cervical decompressive spinal cord or nerve root surgery.
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This study evaluates the spinal canal, its relationship to the spinal cord, and nerve root impingement from disc, spur, or foraminal encroachment.
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CT myelography, still the criterion standard, remains superior to MRI in detecting lateral and foraminal encroachment, despite greater expense and morbidity. Consequently, CT myelography is not the initial imaging study to evaluate cervical spine and is reserved for complicated cases.
MRI
See the list below:
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Advantages include soft-tissue definition (eg, cervical discs, spinal cord), cerebrospinal fluid visualization, noninvasiveness, and lack of patient radiation exposure. (See the images below.)
Axial magnetic resonance imaging (MRI) scan (C3-C4) demonstrating left-sided posterolateral protrusion of the nucleus pulposus with compression of the cerebrospinal fluid.
Sagittal magnetic resonance imaging (MRI) scan demonstrating cervical intervertebral disc protrusions at C3-C4 and C7-T1.
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Newer MRI pulse sequences and higher field magnets provide faster and more detailed imaging.
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Unfortunately, some sequences (eg, spin echo) depict pathology larger than actual size and obscure other abnormalities. Other disadvantages include expense, inability of claustrophobic patients to tolerate the procedure, dependence on patient cooperation to minimize artifact, high false-positive rate, and insensitivity compared with CT scanning in evaluating bony structures.
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Furthermore, MRI appears inferior in differentiating cervical disc prolapse (ie, soft cervical disc) from spondylitic osteophytic compression (ie, hard cervical disc).
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A literature review by Michelini et al indicated that upright MRI can be used to demonstrate spinal problems in symptomatic patients in whom conventional MRI produces negative results, with kinetic MRI allowing patients to be imaged in weight-bearing, flexed, and extended positions. [31]
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Contraindications to MRI include patients with embedded metallic objects, such as pacemakers, surgical clips, spinal cord stimulators, or prosthetic heart valves that may be dislodged by MRI magnets.
Discography
See the list below:
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Provocative cervical discography has been controversial since its introduction in 1957 by Smith. (Examples of discography appear below.)
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This imaging procedure involves sterile-technique placement of spinal needles into cervical intervertebral discs
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At least 2 different techniques exist for performing this procedure.
The paravertebral technique uses digital palpation to retract vital soft-tissue structures (eg, trachea, carotid artery, esophagus).
The oblique approach obviates the need for digital palpation. After spinal needles are placed within the center of the nucleus pulposus, contrast is injected to determine internal disc architecture and any pain response provoked.
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Provocative discography is the only procedure that can determine whether a disc serves as the pain generator.
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Discomfort and invasiveness render this procedure less desirable than cervical MRI, which provides much of the anatomical information that provocative discography does.
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Provocative cervical discography identifies symptomatic disc(s), assisting in evaluation of patients with inconclusive diagnostic tests and presurgical fusion planning.
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Contraindications to provocative discography include large disc herniation and midsagittal spinal canal diameter of less than 12 mm.
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Complications include discitis, epidural abscess, quadriplegia, stroke, pneumothorax, nerve injury, and spinal cord injury. The reported rate of cervical discitis is 0.37%.
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Discography should be performed at all accessible cervical levels, given the high frequency of multilevel symptomatic cervical discs.
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Provocative discography may identify poor surgical candidates, thereby improving fusion outcomes.
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A systematic review of cervical discography has found that if performed using the International Association for the Study of Pain (ISAP) criteria, cervical discography may be a useful tool for the evaluation of discogenic neck pain without disc herniation or radiculitis. Cervical discography was found to have level II-2 strength of evidence for diagnostic accuracy. [32]
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See the images below.
Other Tests
Electrodiagnostic studies continue to be standard for evaluating neurologic function of the cervical spine. Advantages of these tests include limited expense and low morbidity.
Nerve conduction studies (NCSs) and electromyography (EMG) studies provide physiologic assessment of cervical nerve root and peripheral nerve function.
Needle EMG can detect acute, subacute, and chronic radicular features if motor nerve fiber pathology exists.
A diagnosis of radiculopathy is apparent when needle EMG reveals abnormal spontaneous potentials and/or certain changes in motor unit action potentials, in 2 or more muscles innervated by the same nerve root but by different peripheral nerves. Ideally, EMG abnormalities also should be demonstrated in the paraspinal muscles to confirm the diagnosis of radiculopathy.
In a study by Dillingham et al, cervical radiculopathy may be identified as much as 100% of the time using preset muscle screens. If positive findings are found in 1-2 muscle(s) in such screen, this result is positive. [33]
When paraspinal muscles were one of the screening muscles, 5 muscle screens identified 90-98% of radiculopathies, 6 muscle screens identified 94-99%, and 7 muscle screens identified 96-100%. When paraspinal muscles were not part of the screen, 8 distal limb muscles recognized 92-95% of radiculopathies. An 8 muscle screen that excludes the cervical paraspinal muscles is a valuable tool to help diagnose radiculopathy in those patients with prior history of cervical spinal laminectomy.
A compound motor action potential amplitude drop of 50% or more indicates significant axonal loss. This assessment is made via NCS of motor axons.
NCS/EMG is especially helpful in differentiating cervical radiculopathy from confounding neuropathic conditions (eg, ulnar nerve entrapment, carpal tunnel syndrome, peripheral neuropathy, plexopathy).
Unfortunately, cervical radiculopathies involving exclusively sensory axons (ie, without involvement of motor axons) rarely are detected by electrodiagnostic studies, which is a shortcoming of this diagnostic modality. In addition, routine motor NCSs do not evaluate the C6 and C7 nerve roots, which are most commonly involved, or the levels above.
Unlike needle EMG (which involves intramuscular evaluation and is a well-accepted diagnostic test), surface EMG generally is not considered to have an accepted role in the diagnosis of radiculopathy.
Somatosensory evoked potentials (SEPs) evaluate sensory conduction peripherally and centrally.
Lower limb SEPs involving tibial and peroneal nerves, which assess spinal cord conduction, are more sensitive in diagnosing myelopathy than are upper limb median and ulnar SEPs.
Dermatomal evoked potentials have been used to detect cervical radiculopathy but are of questionable value.
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Disc herniation classification. A: Normal disc anatomy demonstrating nucleus pulposus (NP) and annular margin (AM). B: Disc protrusion, with NP penetrating asymmetrically through annular fibers but confined within the AM. C: Disc extrusion with NP extending beyond the AM. D: Disc sequestration, with nuclear fragment separated from extruded disc.
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Axial magnetic resonance imaging (MRI) scan (C3-C4) demonstrating left-sided posterolateral protrusion of the nucleus pulposus with compression of the cerebrospinal fluid.
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Sagittal magnetic resonance imaging (MRI) scan demonstrating cervical intervertebral disc protrusions at C3-C4 and C7-T1.
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Right C7 cervical transforaminal epidural steroid injection demonstrating epidural and radicular spread of radiologic contrast dye.
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Cervical epidural steroid injection at the C7-T1 interlaminar space.
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Cervical discography. Anteroposterior fluoroscopic image.
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Cervical discography. Lateral fluoroscopic image.
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Postdiscography axial computed tomography (CT) scan demonstrating right posterolateral subligamentous protrusion.
