Cervical Radiculopathy

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Chapter Synopsis

Cervical radiculopathy is defined as pain with or without a motor, sensory, or reflex deficit that is caused by cervical nerve root compression or irritation. Typically, cervical radiculopathy has a favorable natural history. This chapter reviews the epidemiology, natural history, pathogenesis, and differential diagnosis of the disease.

Important Points

Neural compression resulting in radiculopathy can result from a variety of sources, the most common being cervical spondylosis and herniated nucleus pulposus.
Consensus statements from a review of available evidence indicate that cervical radiculopathy from degenerative processes has a favorable prognosis and tends to be self-limiting.
Symptoms of cervical radiculopathy frequently mimic those of other diseases; therefore, careful history, examination, and imaging are required to confirm the diagnosis.
Careful correlation of history and examination with imaging studies is necessary because asymptomatic degenerative changes in the cervical spine are very common findings in advanced imaging, in particular magnetic resonance imaging.

As a degenerative condition, cervical radiculopathy results most commonly from spondylosis or herniated nucleus pulposus. Cervical radiculopathy can also have other causes, such as tumor, trauma, synovial cysts, meningeal cysts, dural arteriovenous fistulas, or tortuous vertebral arteries. This chapter focuses on spondylosis and herniated nucleus pulposus.

In 1817, Parkinson published the first clinical description of cervical radiculopathy but misunderstood the etiology. In 1926, Elliott published his work describing how neuroforaminal stenosis caused cervical radiculopathy. In 1948 and 1952, Brain published articles on the intervertebral disk and cervical spondylosis.

Cervical radiculopathy is defined as pain with or without a motor, sensory, or reflex deficit that is caused by cervical nerve root compression or irritation. The irritation may result in one or more of the following signs and symptoms: loss of strength, neck pain, arm pain, and numbness or paresthesias in a dermatomal or myotomal distribution.

Epidemiology

A population-based study from Rochester, Minnesota, revealed an incidence of cervical radiculopathy of 107.3 per 100,000 men and 63.5 per 100,000 women. In this study population, no cervical radiculopathy was seen is persons who were more than 60 years old. The investigators also found that the C7 nerve root was most often involved, followed by C6.

Natural History

The natural history of cervical radiculopathy was initially studied by Lees and Turner in 1963. These investigators followed two groups of patients: one group with myelopathy and the other with radiculopathy. Fifty-seven patients with cervical radiculopathy were followed for up to 19 years. No patients with radiculopathy became myelopathic, but 25% suffered from persistent or worsening radicular pain.

Gore and associates followed 205 patients with neck pain and no neurologic deficit for a minimum of 10 years. At the final follow-up, one third of these patients had moderate to severe pain that limited their lifestyle. Unfortunately, it is difficult to determine how many of these patients had primarily radicular pain, as opposed to isolated neck pain, despite tabular notation in the article of shoulder, arm, forearm, and hand pain in some of the patients.

A more recent article from the Degenerative Disorders Work Group of the North American Spine Society Evidence-Based Clinical Guideline Development Committee noted methodologic problems with all reviewed studies pertaining to the natural history of cervical radiculopathy. This work group proposed the following consensus statement: “It is likely that for most patients with cervical radiculopathy from degenerative disorders signs and symptoms will be self-limited and will resolve spontaneously over a variable length of time without specific treatment.”

Pathophysiology

Most patients with cervical radiculopathy patients present to their physician with symptoms caused by cervical spondylosis and the resultant neuroforaminal stenosis or “hard disk.” Cervical spondylosis starts with disk desiccation. The avascular disk loses water because of a decrease in the proteoglycan content in the nucleus pulposus that leads to a reduction of water content from 90% at birth to 74% during the eighth decade of life. This change results in a loss of disk height, microinstability and subsequent osteophyte formation, facet hypertrophy, and ligamentum flavum buckling and hypertrophy. Degeneration of the spine, or spondylosis, may result in neuroforaminal stenosis and potentially, spinal canal stenosis.

The other main cause of cervical radiculopathy is a “soft disk” or herniated nucleus pulposus. This disorder is seen more often than a hard disk in younger patients. Roughly 75% of cervical radiculopathies occur between the ages of 40 and 59 years. Patients in their 40s tend to have more soft disks, and those in their 50s tend to have more hard disks.

Double crush phenomenon occurs less than 1% of the time on the same nerve, according to Morgan and Wilbourn; it is observed when a cervical nerve root is compressed and is accompanied by additional peripheral compression. These investigators found that 3.4% of the time, a patient had either carpal tunnel syndrome or ulnar neuropathy combined with a cervical root lesion. The double crush phenomenon was first reported by Upton and McComas, who hypothesized that it originated from impaired axoplasmic flow that made the distal portion of the nerve more susceptible to compression injury.

Pertinent Examination Findings by Level

Cervical radiculopathies can result from any pathologic condition at the nerve root level. Above the level of C5, diagnosis can be difficult to elucidate based on history and physical examination because examination findings are limited and nonspecific ( Fig. 13-1 ). C2 radiculopathy is characterized by a history of occipital neuralgia in which the patient has suboccipital or auricular pain. The C3 nerve root, which is the smallest cervical root, exits through the largest foramen and is usually not affected by spondylosis. Because C4 radiculopathy may manifest with pain to the posterior neck, trapezius muscle, and anterior chest, this disorder can sometimes be difficult to differentiate from axial neck pain.