Herniated Nucleus Pulposus of the Cervical Spine Case File

Herniated Nucleus Pulposus of the Cervical Spine Case File

Eugene C. Toy, MD, Andrew J. Rosenbaum, MD, Timothy T. Roberts, MD, Joshua S. Dines, MD

CASE 25

A 45-year-old musician comes to the office complaining of a 3-month history of neck pain that radiates into his right arm. It is “electric” in nature, spontaneously sending a shooting sensation down his arm. Last week, he noted weakness in his right arm with elbow flexion. His pain is relatively constant and is accompanied by some loss of sensation in his thumb and index finger. He is finding it difficult to play the piano with his right hand. The patient gains some relief by lying down, but states that occasional bouts of “shooting” pain are interfering with his sleep. He denies other systemic complaints, such as fevers and chills. His past medical and surgical history is unremarkable except for a 20-pack-year smoking history.

    On physical exam, gait testing demonstrates a fluid, nonataxic, nonantalgic gait. Neck range of motion is decreased with lateral bending and axial rotation to the right side, and neck extension is uncomfortable. Right shoulder range of motion is pain-free. Neurologic testing demonstrates marked weakness with resisted elbow flexion (4/5) and shoulder abduction and forward flexion (4/5) with full strength in all other right upper extremity muscle groups. He has a decreased bicipital reflex as compared with the unaffected side. Capillary refill is brisk. No lesions, ecchymosis, or erythema is present in the arm or hand. Examination of the left upper extremity and both lower extremities are within normal limits. Plain radiographs of the cervical spine and right shoulder are obtained and show no acute pathology, revealing only mild degenerative changes.

► What is the most likely diagnosis?

► What is the next step in therapy?

ANSWER TO CASE 25:

Herniated Nucleus Pulposus of the Cervical Spine                              

Summary: A 45-year-old male smoker presents with 3 months of electric-like pains beginning in his neck and radiating down his right arm. He has weakness in his biceps. Radiographs reveal only mild cervical spondylosis.

• Most likely diagnosis: Cervical radiculopathy due to a herniated nucleus pulposus (HNP).
• Next step in therapy: Nonoperative (conservative) management with overthe- counter medications including acetaminophen and nonsteroidal antiinflammatory drugs (NSAIDs) and possibly muscle relaxants. Short courses of oral corticosteroids, such as methylprednisolone (Medrol) dose packs, are also an option. Brief courses of low-dose narcotics for breakthrough pain may be prescribed, and recommendations for stretching exercises and application of cold and/or warm compresses may be given. Smoking cessation is indicated, as tobacco and nicotine use has been associated with the pathogenesis of degenerative changes in the disk and HNP.

ANALYSIS

Objectives

1. Develop a diagnostic approach to cervical neck pain.
2. Understand the workup for radiculopathic pain.
3. Be familiar with the natural history of HNP and the indications for surgery.

Considerations

This 45-year-old man developed neck pain insidiously. Although he has slight weakness, he does not have any symptoms requiring urgent intervention. A careful history eliminates the possibilities of radiculopathy as secondary to trauma, infection, or other inflammatory neoplastic processes. The physician must be sure to localize the pathology to the cervical spine, as ipsilateral shoulder and upperextremity pathologies such as brachial plexus injury or peripheral nerve entrapment may present similarly. On physical exam, strength, sensation, and reflexes are tested in all applicable myotomal and dermatomal distributions of the bilateral upper and lower extremities. This patient exhibits mild weakness consistent with a right-sided C6 nerve root pathology. Special tests, like the Spurling test, help diagnose nerve root compression at the cervical level. Plain radiographs, although not always necessary on first presentation, are relatively inexpensive and painless and are a simple and convenient way to evaluate for processes other than an HNP, such as fracture or facet arthropathy.

    Given this patient’s history, radiographs consistent with only mild degenerative changes and physical exam findings that include weakness with resisted elbow flexion, positive Spurling test, and blunted biceps reflex, he likely has a C6 radiculopathy due to a C5-6 HNP. There is no clear consensus on whether further imaging is necessary in this patient. Indeed the great majority of patients with spinal radiculopathies experience a spontaneous resolution of symptoms with little more than over-the-counter therapies. Because this patient has yet to try NSAIDs and other conservative treatments, he may be trialed on such therapies before further workup is performed. Should the patient experience a dramatic worsening of symptoms or simply a failure to improve on this regimen, magnetic resonance imaging (MRI) of his cervical spine should be obtained.

APPROACH TO:

Cervical Radiculopathy                                 

DEFINITIONS

RADICULOPATHY: Clinical findings of sensory or motor dysfunction in the distribution of a specific nerve root. Radiculopathies are typically caused by nerve root compression.

HOFFMAN SIGN: A physical exam finding suggestive of upper motor neuron dysfunction in the upper extremity. Hoffman sign is elicited by repeatedly “flicking” the tip of the patient’s index or middle finger and observing for reactive flexion of the thumb or fingers. It is analogous to the Babinski sign of the lower extremities.

SPURLING SIGN: A physical exam finding elicited with neck extension and rotation toward the affected side. The test is positive when the pattern of radicular pain into the upper extremity is reproduced. Spurling sign is highly suggestive of a cervical spine etiology for upper-extremity pain and should be negative in situations in which radicular-like symptoms are caused by brachial plexus or peripheral nerve compressive etiologies.

CLINICAL APPROACH

Anatomy and Pathophysiology

The most common disk level of the cervical spine responsible for radiculopathic pain is C6-7, which typically manifests as symptoms attributable to C7 nerve root dysfunction. A disk herniation at the C5-6 level is the second most common location in the cervical spine.

    Cervical radiculopathy is thought to result from several mechanisms. Most commonly, acute nerve compression occurs from direct nerve root impingement by herniated soft disc material. Typical locations for HNP in the axial plane are posterolateral to the disc space and medial to the uncovertebral joint. Here, the disc-restraining posterior longitudinal ligament and annulus fibrosis are absent, and there is little to restrain an expanding disc when it is placed under pressure. Herniations here typically impinge on the exiting nerve root (ie, the C7 root at C6-7 and the C6 root at C5-6). A second mechanism for cervical nerve root compression may result from chronic disc height loss and hypertrophy of the uncovertebral joint, which is consistent with aging and degenerative disease. Discal height loss may be accompanied by bulging of the disc material or uncovertebral hypertrophy posteriorly against the spinal canal and nerve roots, leading to compression. Similar height loss and degeneration may cause stenosis within the neuroforamina, leading to compression of the exiting nerve root. At least in the acute setting, herniated disc material is thought to be inflammatory in nature and has been associated with the production of inflammatory mediators including interleukin (IL)-1 and IL-6, substance P, bradykinin, tumor necrosis factor α, and prostaglandins.

History and Physical Exam

A thorough history and physical exam should be performed, with special attention to the origin of the patient’s symptoms. A history of traumatic onset may suggest fracture or traumatic disc herniation. A history of neoplastic processes or systemic inflammatory states may be suggestive of nerve compression secondary to tumor growth, pathologic fracture, or epidural abscess. Patients may complain of fever, chills, weight loss, or nocturnal malaise in the setting of radicular pain and neurologic dysfunction. In such cases, workup should include advanced imaging of the cervical spine (typically an MRI) and laboratory studies such as white blood cell count, erythrocyte sedimentation rate, and C-reactive protein. If lesions are suggested or suspected, a more generalized exam for metastatic disease involving computed tomography (CT) or nuclear scanning may be required. Common symptoms consistent with HNP of the cervical spine include complaints of occipital headaches; neck pain, worse with motion; and pain in the neck, shoulder, and arms. Root compression often manifests with paresthesias in the affected extremity. It is important to realize, however, that there is a significant overlap and variance in the dermatomal distributions of nerve roots. Therefore, paresthesias associated with single-nerve root compression may not always follow the textbook dermatomal maps.

    On exam, motor strength is graded on a 0 to 5 scale. Sensory testing should evaluate for both dorsal column and spinothalamic tract function by evaluation of positional and pain/temperature sensations, respectively. Evidence of upper motor neuropathy should be ruled out. For detailed instruction on performing the spinal exam, please refer to the “Approach to the Orthopaedic Patient” section, located near the beginning of this text.

Differential Diagnosis

Before a clinical diagnosis of cervical radiculopathy can be made, several other disease processes must be considered and then ruled out. Most notably, brachial plexus injuries and peripheral nerve entrapment syndromes of the upper extremity may closely resemble the sensory and motor symptomatology of nerve root compression. Other sources of radicular-like symptoms include degenerative changes, stenosis, and space-occupying lesions, such as abscesses or tumors. The presence of upper motor neuron signs (suggested by a positive Hoffman sign or gait changes) would point to either a cervical stenosis causing cord compression or other neurologic conditions such as amyotrophic lateral sclerosis.

Imaging

Once fractures and other pathology are ruled out by plain x-ray, MRI may be considered a next step in the further workup of cervical radicular pain. It must be stated again, however, that because the great majority of these patients experience a spontaneous resolution of symptoms, not every patient presenting with radicular symptoms needs to undergo urgent MRI. In patients with unremitting pain that has failed conservative management, continued or progressive weakness, neurologic decompensation, or bowel or bladder changes, MRI is the gold standard to evaluate spinal cord and root compression in the absence of contraindications. On T2-weighted MRI, cerebrospinal fluid is bright and clearly distinguishes areas of compression and patency. In patients for whom MRI is contraindicated, most commonly those with pacemakers or interventions for intracerebral aneurysms, CT myelography may offer a clear visualization of the spinal cord and roots.

TREATMENT

Nonoperative Treatment

Acute cervical radiculopathy typically has a self-limited course. In fact, 75% of these patients improve without surgical intervention. The first line against cervical radiculopathic pain should be NSAIDs and/or acetaminophen. NSAIDs play a distinct role in attenuating the painful local inflammatory response resulting from disc herniations and their inflammatory effects on nerve roots and may decrease pressure around affected nerve roots. Low-dose narcotic analgesics, although not commonly recommended for chronic treatment, may be necessary to control acute pain that is refractory to NSAIDs and acetaminophen. Adjunctive treatment with muscle relaxants such as cyclobenzaprine may help decrease associated painful muscle spasms and may decrease narcotic requirements in certain patients. Although current literature fails to demonstrate their clear efficacy, brief courses of oral corticosteroids are sometimes prescribed to decrease inflammatory responses to HNP. Adjunctive therapies such as physical therapy, massage therapy, and the application of heat or ice packs are not strongly supported by the literature, but may be used if helpful to the patient.

    When conservative measures fail, epidural steroid injections may offer some transient relief but have not been shown to alter the natural history of the disease process. Localized steroid injections may have an anti-inflammatory effect on irritated nerve roots and may play a role in the inhibition of pain pathways. The true efficacy of epidural injections is debated and varies greatly between individuals.

Surgical Treatment

When nonsurgical treatment fails to relieve symptoms, or if neurologic deficits progressively worsen, surgical decompression may be necessary. As a general rule, surgical approaches to the cervical spine should be directed “where the pathology is.” Because herniation originates in the disc space, an anterior surgical approach is preferred in the setting of central and posterolateral anterior compressive pathology. Anterior cervical discectomy and fusion (ACDF) is the most common surgical treatment for cervical HNP. For isolated single-level nerve root compression, posterior approaches to the cervical spine may be used if the pathology is accessible through the neural foramen. Posterior laminoforaminotomy relieves pressure on the nerve root by unroofing the neuroforamen and allowing the root to decompress. This technique preserves motion between vertebral levels because the disc is left intact, and thus fusion of vertebral segments is unnecessary. Surgical outcomes for relief of radicular pain range from 80% to 90% with either anterior or posterior approaches.

    Lastly, a relatively new and controversial technique in the treatment of singlelevel disease is cervical disc arthroplasty (replacement). Although limited in both application and supporting data at this time, this promising procedure may offer the best of both worlds: preserving motion between segments while allowing for a thorough discectomy and decompression.

Complications

Although ACDF procedures typically have good outcomes, they are not without potential complications. The anterior approach to the cervical spine puts several vulnerable neurovascular structures at risk, including the recurrent laryngeal nerve (1% risk of injury with ACDF) and, to a lesser degree, the hypoglossal nerve, vagal nerve, and the carotid arteries. Horner syndrome is “classically” characterized by ptosis, anhidrosis, and miosis and results from injury to the sympathetic chain, located laterally to the longus colli muscles at the C6 level. Finally, pseudarthrosis, or the failure of bony fusion, may occur at rates as high as 5% to 10% for singlelevel fusions. Rates dramatically increase to 30% to 40% for multiple-level fusions, but few pseudoarthroses are actually symptomatic or require revision work. Tobacco and chronic corticosteroid use is a significant risk factor for the development of pseudoarthrosis.

COMPREHENSION QUESTIONS

25.1 A 56-year-old female bodybuilder presents to your clinic after straining her neck during an overhead clean and jerk contest. She complains of numbness in her middle finger and weakness in her elbow extension. Which of the following findings would most likely be present in this patient?

A. Elbow flexion weakness

B. Finger grip weakness

C. Decreased biceps reflex

D. Decreased sensation over the ring and small fingers

E. Decreased triceps reflex

25.2 A 49-year-old downhill skier “tweaks” his neck while loading heavy ski equipment atop his family SUV. He complains of 3 days of small finger numbness and difficulty gripping his ski poles. Which of the following nerve roots is most likely entrapped?

A. C5

B. C6

C. C7

D. C8

E. T1

25.3 A 42-year-old construction worker has experienced 8 weeks of unremitting left biceps weakness, wrist extensor weakness, and both pain and numbness in his index finger and thumb. His pain is especially bad when turning his head to the left. He has tried oral steroids, opiates, NSAIDs, acetaminophen, acupuncture, and a local steroid injection 3 weeks ago; all have failed to provide adequate relieve. He states his biceps and wrist weakness is getting worse, as he is now unable to lift even a glass of water with his left arm. MRI confirms HNP at the left-sided C5-6 neuro foramen. What is the next best step in the management of this patient?

A. Repeat corticosteroid injection at C5-6 level

B. Anterior cervical discectomy and fusion (ACDF) of C5-6

C. Increasing oral steroid dosing

D. Prescribing a hard collar for neck immobilization

E. CT scan and/or bone scan to rule out fracture or other injury

ANSWERS

25.1 E. This patient has a C6-C7 HNP affecting the C7 nerve root, which is classically responsible for elbow extension and wrist flexion. The triceps reflex is most commonly associated with C7 nerve root pathology, making E the correct answer choice.

25.2 D. Grip strength and sensation to the small and sometimes ring fingers are classically attributed to the C8 nerve root, most often affected by C7-T1 disc herniations.

25.3 B. ACDF of C5-6 disc with fusion is an effective and highly successful procedure for patients with clearly defined symptomatology and imaging consistent with pathology. This patient has progressive neurologic changes consistent with a well-defined dermo/myotomal distribution. He has failed conservative therapy; increasing steroid dosing and even additional steroid injection are unlikely to help. Further imaging is unnecessary given the consistency between his symptoms and MRI and a lack of suspicion for further injury.

    CLINICAL PEARLS    

► More than 75% of patients with cervical radiculopathic pain improve without surgical intervention. ► NSAIDs and acetaminophen are the mainstays and first line against cervical radiculopathy. ► Beware of treating MRI findings without a careful clinical correlation. MRI has high rate of false positives, with almost 30% of normal, asymptomatic individuals > 40 years of age positive for HNP or foraminal stenosis on MRI.

REFERENCES

Nordin M, Carragee EJ, Hogg-Johnson S, et al, for the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders. Assessment of neck pain and its associated disorders: results of the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders. Spine . 2008;33(4 suppl):S101-S122. 

Rhee JM, Yoon T, Riew D. Cervical radiculopathy. J Am Acad Orthop Surg. 2007;15:486-494. 

Shelerud RA, Paynter KS. Rarer causes of radiculopathy: spinal tumors, infections, and other unusual causes. Phys Med Rehabil Clin N Am . 2002;13:645-696. 

Tong HC, Haig AJ, Yamakawa K. The Spurling test and cervical radiculopathy. Spine . 2002;27:156-159.

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