Cervical Radiculopathy

Shawn M. Bifano

John D. Koerner

Alan S. Hilibrand

Introduction

Cervical radiculopathy is defined as a neurologic disorder resulting in pain in a radicular pattern to one or both upper extremities secondary to cervical nerve root dysfunction. It can present as pain in the neck and arm, with a combination of sensory loss, pain, loss of motor function, or reflex changes in the affected nerve root distribution. Cervical nerve root dysfunction is often the result of a disk herniation or degenerative arthritic spurs causing compression of the nerve roots exiting the corresponding cervical disk level. The resulting pain usually follows a dermatomal or myotomal pattern.

A complete understanding of the differential diagnosis of radicular pain from the neck into the upper extremity is imperative given the broad range of pathologies that may present with pain similar to the characteristic pain in cervical radiculopathy. The diagnosis should begin with a thorough history and physical exam, and then be confirmed with appropriate diagnostic imaging and/or testing. The ensuing chapter will include the relevant anatomy, pathogenesis, epidemiology, diagnosis, and treatment of cervical radiculopathy. Suggested readings will be presented at the end of the chapter.

Relevant Anatomy

There are seven cervical vertebrae. The atlas (C1) and the axis (C2) are considered the upper cervical vertebrae, and the C3–C7 levels are considered the subaxial cervical spine, where the pathology of cervical radiculopathy most commonly originates. A thorough understanding of the neuroanatomy is necessary to identify the source of symptoms and correlates physical exam findings with imaging studies. In the cervical spine, the nerve root exits above the pedicle of the same number (e.g., the C6 nerve root exits above the C6 pedicle in the C5–C6 interspace). For this reason, the C8 nerve root exits above the T1 pedicle in the C7–T1 foramen.

Acute radiculopathy is commonly due to disk herniation, which causes compression of the exiting nerve root. Narrowing of the foramen from arthritis and disk space collapse can also cause symptoms of radiculopathy. The borders of the foramen are the:

vertebral body;
disk;
uncovertebral joints;
facet joints;
cranial and caudal pedicles.

Mechanical compression of the nerve can arise from any of these structures, although the most common sources are the intervertebral disk (herniated nucleus pulposus), and the uncovertebral and facet joints (due to spondylotic disease and degenerative arthritis).

The intervertebral disk consists of the outer annulus fibrosus which is made primarily of type I collagen, and the inner nucleus pulposus which is primarily type II collagen with an extracellular matrix of proteoglycans. The water content of the disk decreases as a person ages, along with the proteoglycan content, which alters the ability of the disk to distribute forces evenly. Circumferential tears in the annulus occur throughout the normal aging process, and may predispose to patients to disk herniations that can result from relatively minor trauma. Many patients with cervical radiculopathy due to a disk herniation do not recall any trauma prior to onset of symptoms.

Pathogenesis

Unlike lumbar radiculopathy, the most common cause of cervical radiculopathy is encroachment of the foramen of the spinal nerve due to spondylosis (70% to 75%). Herniation of the nucleus pulposus accounts for about 25% to 30% of cases of cervical radiculopathy. Encroachment of the foramen is secondary to a decrease in disk height or degenerative changes in the disk such as osteophyte formation. Other less common causes that may decrease the foraminal space include tumor, infection, and trauma.

The mechanisms that cause cervical radicular pain are not completely understood. Unless the dorsal root ganglion is compressed, nerve root compression by itself
does not always lead to pain. Hypoxia and local ischemia of the nerve may lead to aggravation of the compressed nerve root. Evidence has shown that herniated cervical disks release inflammatory markers including matrix metalloproteinases, interleukin-6, interleukin-8, nitric oxide, tumor necrosis factor, and prostaglandin E2. The aforementioned evidence provides the basis for anti-inflammatory treatments.

Epidemiology

Population-based studies have estimated the incidence of cervical radiculopathy; however, these studies may underestimate the true incidence. One study over a 15-year period estimated the point incidence of cervical radiculopathy being 107.3 per 100,000 for men and 63.5 per 100,000 for women, with peak incidence at 50 to 54 years of age. A history of physical exertion or trauma preceded the onset of symptoms in only 15% of the cases. In a more recent study, a military population was studied between the years of 2000 and 2009. A total of 24,742 people were diagnosed within the period of the study giving an incidence of 1.79 per 1,000 person-years. The risk factors associated with cervical radiculopathy include cigarette smoking, white race, and increasing age. Population-based studies conflict on whether or not there is a gender predilection with regards to radiculopathy; however, most large studies demonstrate a slightly higher rate in men.

Diagnosis

History and Physical Exam

The diagnosis of cervical radiculopathy should start with a focus on the chief complaint, which often includes varying degrees of pain, weakness, or sensory loss in the affected dermatome(s) or myotome(s) of the affected nerve root(s). The pain may be described in a range from dull, aching pain to a stabbing, sharp, burning pain. Acute or insidious presentation can lead to different pathologies in the differential diagnosis. Knowledge of the innervations of each cervical root is needed to localize the pathology. The differential diagnosis should include, but is not limited to:

axial neck pain;
cardiac pathology;
peripheral entrapment neuropathies;
thoracic outlet syndrome;
neoplasms;
herpes zoster;
rotator cuff disease.

Additionally, symptoms may not follow the typical dermatomal or myotomal pattern of the affected cervical nerve root. Significant variability exists between patients due to anatomical differences such as intradural connections between nerve roots. Red flag signs of myelopathy or neoplasm should not be overlooked. Red flag signs include significant weight loss, night sweats, loss of coordination, changes in bowel/bladder function, unremitting night pain, immunosuppression, and history of cancer. Social history is important in a patient presenting for radicular pain. A history of smoking, axial load bearing, occupations with overhead lifting, and illegal drug use may also be relevant.

The physical exam begins with observation of the patient. It is important to note the patient’s posture, specifically how the patient supports his/her head, neck, and arms. Atrophy in particular muscles may be observed, particularly in the shoulder and periscapular area. The patient’s range of motion is important in cervical radiculopathy. Motions that enlarge the intervertebral foramen of the affected side may alleviate the symptoms experienced by the patient. Specifically, abduction of the affected arm over the patient’s head may enlarge the foramen and temporarily relieve the symptoms. Next, the area is localized by palpation, checking for muscle spam and areas of tenderness.

There are physical exam findings and maneuvers that help in distinguishing cervical radiculopathy from a broad range of pathologies within the differential diagnosis. The sensitivity and specificity need to be taken into account while performing specific physical exam maneuvers. Three highly specific maneuvers (used to rule in cervical radiculopathy) are as follows:

Spurling maneuver
The neck distraction test
Valsalva maneuver

The Spurling maneuver is performed by turning the patient’s head toward the affected side, extension, and applying axial compression. A positive Spurling sign reproduces the patient’s radicular pain. The neck distraction test is performed by placing one hand under the patient’s chin and the other hand around the back of the patient’s head while slowly lifting the head. A positive test is alleviation of the patient’s symptoms when the head is lifted. The Valsalva maneuver is carried out by instructing the patient to take a deep breath and holding it while attempting to exhale. A positive Valsalva test occurs when there is reproduction of the patient’s symptoms. A highly sensitive test (to rule out cervical radiculopathy) is used to accompany the findings of the aforementioned physical exam maneuvers:

Upper limb tension test.

The upper limb tension test is performed with the patient in the supine position. A series of upper extremity manipulations are then performed, including scapular depression, shoulder abduction, forearm supination with wrist and finger extension, shoulder external rotation, elbow extension, and contralateral and ipsilateral cervical lateral flexion. The test is considered positive if
pain is reproduced. A negative test essentially rules out cervical radiculopathy.

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