Cervical Radiculopathy

Background

Cervical radiculopathy is a dysfunction of a nerve root of the cervical spine. The seventh (C7; 60%) and sixth (C6; 25%) cervical nerve roots are the most commonly affected.[1, 2, 3, 4, 5, 6, 7]

Sagittal magnetic resonance image of the cervical spine. This image reveals a C6-C7 herniated nucleus pulposus. Axial magnetic resonance image of the cervical spine. This image reveals a C6-C7 herniated nucleus pulposus.

In the younger population, cervical radiculopathy is a result of a disc herniation or an acute injury causing foraminal impingement of an exiting nerve.[8] Disc herniation accounts for 20-25% of the cases of cervical radiculopathy. In the older patient, cervical radiculopathy is often a result of foraminal narrowing from osteophyte formation, decreased disc height, degenerative changes of the uncovertebral joints anteriorly and of the facet joints posteriorly.

Factors associated with increased risk include heavy manual labor requiring the lifting of more than 25 pounds, smoking, and driving or operating vibrating equipment. Other, less frequent causes include tumors of the spine, an expanding cervical synovial cyst, synovial chondromatosis in the cervical facet joint, giant cell arteritis of the cervical radicular vessels, and spinal infections.[9, 10] The purpose of this article is to provide information on the presentation, evaluation, differential diagnosis, and treatment of cervical radiculopathy.

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NextEpidemiologyFrequencyUnited States

Cervical radiculopathy occurs at a much lower frequency than radiculopathy of the lumbar spine. The annual incidence is approximately 85 cases per 100,000 population.

PreviousNextFunctional Anatomy

Seven cervical vertebrae and 8 cervical nerve roots exist. The C1-2 (atlantoaxial) joint forms the upper cervical segment.[1, 3, 11, 12] This joint allows for 50% of all cervical rotation. The occipitoatlantal joint is responsible for 50% of flexion and extension. Below the C2-C3 level, lateral bending of the cervical spine is coupled with rotation in the same direction. This is due to the 45° inclination of the cervical facet joints.

The vertebral bodies of C3-C7 are similar in appearance and function. They articulate via the zygapophyseal or facet joints posteriorly. On the lateral aspect of the vertebral bodies are sharply defined margins, which articulate with the facet above. These articulations are called uncovertebral joints, or the joints of Luschka. These joints can develop osteophytic spurs, which can narrow the intervertebral foramina.

Intervertebral discs are located between the vertebral bodies of C2-C7. The discs are composed of an outer annular fibrosis and an inner nucleus pulposus and serve as force dissipators, transmitting compressive loads throughout a range of motion (ROM). The intervertebral discs are thicker anteriorly and therefore contribute to normal cervical lordosis.

The foramina are largest at C2-C3 and progressively decrease in size to the C6-C7 level. The nerve root occupies 25-33% of the foraminal space. The neural foramen is bordered anteromedially by the uncovertebral joints, posterolaterally by facet joints, superiorly by the pedicle of the vertebra above, and inferiorly by the pedicle of the lower vertebra. Medially, the foramina are formed by the edge of the end plates and the intervertebral discs. The nerve roots exit above their correspondingly numbered vertebral body from C2-C7. C1 exits between the occiput and atlas, and C8 exits below the C7 vertebral body. Degenerative changes of the structures that form the foramina can cause nerve root compression. This compression can occur from osteophyte formation, disc herniation, or a combination of the 2.

PreviousNextSport-Specific Biomechanics

Cervical radiculopathy in athletes can occur from several mechanisms. These injuries can occur from an extension, lateral bending, or rotation mechanism, which closes the neural foramen and results in ipsilateral nerve root injury. Conversely, a traction injury can occur with a sudden flexion or extension, coupled with lateral bending away from the affected nerve root.

Additionally, cervical disc herniations can occur with a sudden load with the neck in either flexion or extension. In elderly persons with osteophyte formation, repetitive neck extension and rotation in certain sports, such as swimming or tennis, may result in a more insidious injury.

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Lumbosacral Radiculopathy

Background

Some of the major causes of acute and chronic low back pain (LBP) are associated with radiculopathy. However, radiculopathy is not a cause of back pain; rather, nerve root impingement, disc herniation (see the image below), facet arthropathy, and other conditions are causes of back pain.[1, 2, 3]

Sagittal magnetic resonance image showing loss of intervertebral disc height at L5/S1. Herniations of the nucleus pulposus are noted at L4/5 and L5/S1. Courtesy of Barton Branstetter, MD.

Lumbosacral radiculopathy, like other forms of radiculopathy, results from nerve root impingement and/or inflammation that has progressed enough to cause neurologic symptoms in the areas that are supplied by the affected nerve root(s).

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Lumbosacral radiculopathy occurs in approximately 3-5% of the population, and men and women are affected equally, although men are most commonly affected in their 40s, whereas women are most commonly affected between ages 50-60.[4] Of those who have this condition, 10-25% develop symptoms that persist for more than 6 weeks.

PreviousNextFunctional Anatomy

The anatomy of the lumbar epidural space is the key to understanding the mechanism of lumbosacral radiculopathic pain. The sinuvertebral nerves innervate structures in the lumbar epidural space; these nerves originate distal to the dorsal root ganglion, then run back through the intervertebral foramen to supply the arteries, venous plexi, and lymphatics. At the inner aspect of the intervertebral foramen, the sinuvertebral nerves divide into ascending and descending branches that freely communicate with corresponding branches from the segment above, from the segment below, and from the opposite side.

The sinuvertebral nerve supplies the posterior longitudinal ligament, superficial annulus fibrosus, epidural blood vessels, anterior dura mater, dural sleeve, and posterior vertebral periosteum. The 2 structures capable of transmitting neuronal impulses that result in the experience of pain are the sinuvertebral nerve and the nerve root. The posterior rami of the spinal nerves supply the apophyseal joints above and below the nerve as well as the paraspinous muscles at multiple levels.

Herniation of the intervertebral disc can cause impingement of the above neuronal structures, thus causing pain. The presence of disc material in the epidural space is thought to initially result in direct toxic injury to the nerve root by chemical mediation and then exacerbation of the ensuing intraneural and extraneural swelling, which results in venous congestion and conduction block. Notably, the size of the disc herniation has not been found to be related to the severity of the patient's pain.

Pain is also believed to be mediated by inflammatory mechanisms that involve substances such as phospholipase A2, nitric oxide, and prostaglandin E. These mediators are all found in the nucleus pulposus itself. Phospholipase A2 has been found in high concentrations in herniated lumbar discs; this substance acts on cell membranes to release arachidonic acid, a precursor to other prostaglandins and leukotrienes that further advance the inflammatory cascade. Additionally, leukotriene B4 and the substance thromboxane B2 have been found to have direct nociceptive stimulatory roles.

From a biomechanical standpoint, the lumbar intervertebral discs are highly susceptible to herniation because they are exposed to tremendous forces, principally by the magnification of the forces that result from the lever effect of the human arm in lifting; the forces generated by the upper trunk mechanics with rotation, flexion/extension, and side-bending on the discs below; and by the vertical forces associated with the upright position. Because each intervertebral disc is a fluid system, hydraulic pressure is generated whenever a load is placed on the axial skeleton. The hydraulic pressure mechanisms then multiply the force on the annulus fibrosus of the intervertebral disc to make it 3-5 times that which is exerted on the axial skeleton.

PreviousNextSport-Specific Biomechanics

Dancers are prone to both acute and chronic back problems, including lumbosacral radiculopathy, which develop secondary to the combination of 2 factors that are required in most dance routines: extreme physical flexibility and exposure of the spine to the extremes of its range of motion.[1] Additionally, female dancers are predisposed to disc herniation secondary to the positioning that is required in certain movements, such as the pas de deux (in which excess lumbar lordosis is present), as well as the large jumps that these dancers often perform.

Golfers are also very susceptible to disc disease and lumbosacral radiculopathy because of the repetitive torsional motion that is used in the sport.[5] The golf swing can produce up to an estimated 7500 N of compressive force across L3-L4. Competitive weight lifters and football linemen have been noted to experience even larger compressive loads.

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