Medical Management of Neck and Low Back Pain

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Chapter 188 Medical Management of Neck and Low Back Pain

Back pain is common and costly. It was the most frequent type of pain reported by U.S. respondents in the 2002 National Health Information Survey (NHIS), with more than one fourth of adults reporting an episode of low back pain lasting at least 1 day in the preceding 3 months.1 In the NHIS survey, neck pain ranked third, with 13.8% of persons reporting at least a 1-day episode. Back pain ranks in the top five reasons for visits to primary care physicians in the United States.1,2 Up to 71% of the adult population may experience a significant episode of neck pain in their lifetimes.3 Approximately 2% of the U.S. workforce sustains a compensable back injury each year.4 The direct cost of health care attributed for low back pain exceeds $25 billion dollars in the United States.5 The largest proportion of direct medical costs for back pain is spent on physical therapy (17%), followed by pharmacy (13%) and primary care physician visits (13%).6 Indirect costs related to lost productivity in the workplace or homes are substantially higher than the direct costs of back pain.6

An appreciation of the benign short-term prognosis of acute nonradicular low back pain is fundamental to the management of these patients. Most patients recover within 1 month and more than 90% of patients have returned to work by 3 months.7 However, about one fourth of patients have persistent symptoms at 3 months and about 20% have substantial limitations of activity at 1 year.8,9 Clearly, an important objective of medical treatment should be to reduce the likelihood of progression from acute symptoms to chronic pain and functional impairment. The primary determinants of persistent disability at 12 months are psychosocial in nature.8,10 In fact, psychosocial variables have been shown to be superior to structural findings or discography as predictors of both long- and short-term disability, duration of symptoms, and health care visits for back pain.11 High levels of psychological distress, depressive mood, and somatization are well established as risk factors for transition from acute back pain to chronicity.8,12 Coping styles characterized by catastrophizing or fear avoidance are suspected but less well established as predisposing to the development of chronic symptoms. Failure to recognize these psychosocial issues in patients with low back pain will frustrate even the most well-conceived medical management strategy.

Etiology of Back and Neck Pain

The specific anatomic etiology of nonradicular spinal pain is often ambiguous. Up to 85% of patients have pain that cannot be assigned to a particular pain generator.13 “Abnormal” findings on plain radiographs, including spondylolysis, spondylolisthesis, facet joint degenerative changes, Schmorl nodes, and mild scoliosis, are common in asymptomatic persons.14 Radiography of the lumbar spine in patients with back pain of at least 6 weeks’ duration (mean, 10 weeks) has been shown to increase patient satisfaction without any improvement in functional outcome or severity of pain.15 The addition of lateral dynamic flexion-extension radiographs to the initial evaluation of patients with low back pain rarely provides information that alters clinical management, at the expense of significant additional cost and radiation exposure.16 Disc abnormalities are found on MRI in more than 50% of asymptomatic persons by age 40 years and include degenerative disc bulging and protrusions as well as Schmorl nodes.17 The lack of specificity of clinical symptoms and signs for the multiple potential sources of spinal pain—ligaments, facet joints, discs, paravertebral musculature—confounds the attempt to attribute symptoms to radiographic findings. In some patients previously categorized as having nonspecific pain, interventional diagnostic techniques, including discography, facet joint medial branch block or injection, and sacroiliac joint injection, may suggest a specific pathoanatomic etiology. However, these studies have high false-positive rates, particularly in patients with psychosocial issues, and fail to reliably predict the success of specific surgical or interventional treatments.11,14

Cancer and infection are serious but fortunately uncommon specific causes of back pain found in 0.7% and 0.01%, respectively, of patients presenting in a primary care setting.13 The spine is one of the most common sites of metastasis, most commonly arising from breast, lung, prostate, or kidney primary tumors.18 Ankylosing spondylitis is identified in about 0.3% of patients with low back pain, typically younger men.14 Acute or subacute vertebral compression fractures are identified in about 4% of patients. A variety of nonspinal conditions may present with symptoms that mimic spine disorders. These include common musculoskeletal problems such as greater trochanteric bursitis and osteoarthritis of the hip, as well as visceral problems such as kidney stones, aortic aneurysms, and peptic ulcers.

The American College of Physicians and American Pain Society’s recently published evidence-based clinical practice guideline for the management of back pain suggests a focused history and physical examination should permit placement of patients with back pain into one of three broad categories: nonspecific low back pain, back pain with radicular symptoms including lumbar spinal stenosis, and back pain associated with another specific spinal cause.13 Diagnostic imaging is recommended only when a serious etiology (cancer or infection) is suspected or when surgical or other interventional treatment is imminent (Box 188-1). For patients with nonspecific, nonradicular back pain, the guideline incorporates education, activity, physical therapy, medications, and a range of nonpharmacologic therapies.

Medical Treatment Options

Prevention

In view of the enormous personal, societal, and financial burden of back pain, numerous preventive approaches have been investigated. A recent systematic review of prospective, controlled trials of interventions to prevent back pain in working-age adults identified 20 trials that met inclusion criteria.19 Only exercise, in seven of eight trials, was found effective in preventing self-reported episodes of back pain. A variety of exercise approaches were used, including stretching, strengthening of abdominal, back, and leg muscles, and general conditioning. Interventions found ineffective in reducing back pain episodes included stress management, shoe inserts, back supports, ergonomic and back education, and reduced lifting programs. Although evidence for efficacy in prevention of back pain is lacking, smoking cessation and reduction to appropriate weight for height should be encouraged because both smoking and obesity have been associated with increased severity of back symptoms.20,21

Exercise and Physical Therapy

For patients with acute (<4 weeks) back or neck pain, there is little evidence that formal physical therapy is necessary.22 The best advice for such patients is probably to continue with their usual activities as tolerated. In fact, early referral to physical therapy prolonged duration of symptoms compared with patients simply advised to stay active.23 For patients with persistent chronic neck or back symptoms, however, exercise therapy is the cornerstone of medical treatment to decrease pain and restore function and mobility. An impairment-based manual physical therapy and exercise program resulted in clinically and statistically significant short- and long-term improvements in pain, disability, and patient-perceived recovery in patients with mechanical neck pain compared with a program comprising advice, mobility exercise, and subtherapeutic ultrasonography.24 Similarly, a recent meta-analysis found that exercise therapy was effective at decreasing pain and improving function in adults with chronic low back pain and may improve work absenteeism in patients with subacute symptoms.22 Unfortunately, studies comparing different exercise approaches, including stabilization, McKenzie, Pilates, and general aerobic conditioning, are insufficient to strongly recommend a single approach in a particular subset of patients. However, two recent studies have suggested that selection of a physical therapy approach based on diagnosis or mechanical assessment is more effective than general nonspecific exercise advice.25,26

General aerobic conditioning is often recommended for patients with chronic neck or back pain. The sense of well-being and accomplishment acquired from a planned aerobic exercise program such as walking, running, cycling, or swimming creates a positive treatment milieu and further establishes the extent of patient motivation and commitment to the overall treatment plan. Patients participating in an aerobic exercise program have been shown to receive fewer prescriptions for pain, were given fewer physical therapy referrals, and had improved mood states and lessened depression.27

Evidence suggests the superiority of neck stabilization exercises, with some advantages in pain and disability outcomes, compared with isometric and stretching exercises in combination with physical therapy agents (transcutaneous electrical nerve stimulation, continuous ultrasonography, and infrared irradiation) for the management of neck pain.28 There is moderate evidence that lumbar stabilization exercises are effective in improving pain and function in a heterogeneous group of patients with chronic low back pain.29 Unfortunately, available studies are unable to define a specific subgroup of patients with chronic low back pain most suitable for this exercise approach. The current evidence suggests that in the short term, lumbar extensor strengthening exercise administered alone or with cointerventions is more effective than no treatment and most passive modalities in improving pain, disability, and other patient-reported outcomes in chronic low back pain.30

Yoga and Pilates exercises have grown in popularity over the last decade and represent two mind-body exercise interventions that address both the physical and mental aspects of pain with core strengthening, flexibility, and relaxation. There has been a gradual trend toward inclusion of these nontraditional exercise regimens into treatment paradigms for back pain, although few studies critically examining their effects have been published.31 A retrospective analysis of two randomized, controlled trials and one case-controlled series found significant improvement in general function and pain with the Pilates approach in treating nonspecific chronic low back pain in adults. However, as with other exercise paradigms, currently available data do not predict which groups of patients might be best managed with this approach.32

The McKenzie method is a unique and comprehensive approach to neck or low back pain that includes both assessment and intervention. The assessment is designed to detect a directional preference, which refers to a particular direction of movement or sustained posture that causes symptoms to centralize, decrease, or be abolished. Centralization is defined as the sequential and lasting abolition of all distal referred symptoms and subsequent abolition of any remaining spinal pain in response to a single direction of repeated movements or sustained postures. The finding of centralization has positive prognostic value, provided treatment is guided by assessment findings. Noncentralization is a strong predictor of poor prognosis and correlates well with “nonorganic” signs.33 In limited clinical trials, McKenzie-based therapy produces results comparable with those of stabilization or strengthening programs.34,35

Aquatic exercise is potentially beneficial to patients suffering from chronic low back pain and pregnancy-related low back pain.36 Patients with barriers to land-based programs, including lower extremity joint disorders and obesity, are often able to exercise actively in the pool.

Medication

In addition to passage of time, participation in an active exercise program, and use of nonpharmacologic treatments, medicinal treatment is an important component of medical management of neck and back pain. Medications with reasonable evidence of short-term effectiveness for low back pain include nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, skeletal muscle relaxants (for acute low back pain), and tricyclic antidepressants (for chronic low back pain).37 Evidence suggests that NSAIDs are no more effective than pure analgesics for low back pain.38

Acetaminophen

Acetaminophen (acetyl-para-aminophenol [APAP]) has analgesic and antipyretic properties comparable with aspirin, but its anti-inflammatory effects are weak. APAP’s analgesic effects and excellent safety profile make it a reasonable first-line medication for acute back and neck pain. Peak analgesic effects are typically noted from 30 to 60 minutes after ingestion. APAP is relatively inexpensive and produces fewer adverse reactions than NSAIDs. Although recent systematic reviews have found APAP as effective as NSAIDs in the treatment of back pain, in other musculoskeletal disorders, particularly osteoarthritis of the hip or knee, NSAIDs provide better pain relief.39 The accepted oral dose of acetaminophen is 325 to 1000 mg every 4 to 6 hours, not to exceed 4000 mg in 24 hours. The most serious adverse effect of acute acetaminophen overdosage is hepatotoxicity. Risk of hepatotoxicity is increased in patients with known liver disease, heavy alcohol use, or severe fasting states due to vomiting, diarrhea, or severe flu. A major current concern is accidental overdosage in patients who take APAP in addition to a prescription analgesic containing APAP. In adults, serious hepatotoxicity may occur from a single dose of 10 to 15 g.

Nonsteroidal Anti-Inflammatory Drugs

The NSAIDs relieve both pain and inflammation and are a reasonable choice as a first-line agent for the control of acute low back or neck pain in patients without significant risk factors for adverse effects. A recent systematic review of randomized, controlled trials found NSAIDs were effective for short-term relief of acute and chronic back pain, but no more effective than acetaminophen.40 This review and others have concluded that all NSAIDs, including cyclooxygenase-2 (COX-2) inhibitors, are equally effective in treating low back pain.41 Because efficacy among these drugs is comparable, the choice of a particular NSAID is based on cost and safety, particularly in patients at higher risk for adverse effects. GI toxicity is the major limiting factor to NSAID therapy, with serious ulcer complications (bleeding or perforation) seen in about 1.5% of treated patients. All NSAIDs may increase the risk of a cardiovascular event in patients at risk. The American Heart Association recommendations for drug therapy for musculoskeletal pain in patients at cardiovascular risk favor pure analgesics as the drugs of first choice, with nonacetylated salicylates such as salsalate or non-COX-2–selective drugs (particularly naproxen) as alternative choices.42 Other potential side effects include renal failure, tinnitus, fluid retention, and high blood pressure. Although some variability with regard to adverse effects has been recognized, all NSAIDs can cause central nervous system side effects such as drowsiness, dizziness, and confusion. If an NSAID is used, frequent clinical and laboratory monitoring for adverse renal or GI reactions is mandatory. Risk factors for NSAID toxicity include age older than 65 years, known or suspected cardiovascular disease, history of congestive heart failure, history of recent GI bleed or ulcer, kidney disease, hepatic cirrhosis, and history of aspirin-induced respiratory disease. NSAIDs should also be avoided in patients in the third trimester of pregnancy. Acetaminophen is relatively inexpensive with a superior safety profile to NSAIDs and is the first choice in such high-risk patients.43

Oral Steroids

Medications such as prednisone and methylprednisolone are potent corticosteroids with strong anti-inflammatory properties. Corticosteroids are effective in the treatment of inflammatory reactions associated with allergic states, rheumatic and autoimmune diseases, and respiratory disorders. Studies designed to investigate the use of oral steroids in the setting of low back or neck pain are limited. A placebo-controlled trial of a single dose of intravenous methylprednisolone in acute low back pain demonstrated no significant improvement in the steroid-treated group.44 Despite lack of any published evidence for efficacy, oral corticosteroids are widely prescribed to treat acute back or neck pain, particularly with radicular symptoms. Dosage schedules vary, but 7 to 14 days of tapering from a prednisone equivalent dose of 40 to 60 mg is typical. Patients with diabetes should be warned about steroid-induced hyperglycemia. The risk of steroid-induced osteonecrosis is a concern, but the risk appears low.

Opioids

Since the initial report of Portenoy and Foley describing the use of long-term opioid analgesics in treating nonmalignant pain, opioids have gained increasing acceptance as an appropriate therapy for carefully selected patients with spinal pain.46 A recent study found 66% of patients treated in an orthopaedic spine practice received opioids, 25% for longer than 3 months.47 Despite increasing use, concerns about long-term opioid use in chronic nonmalignant pain remain, including risk of abuse, tolerance, and dependence as well as fear of disciplinary action by medical boards for prescribing physicians. In addition, studies of opioids in chronic back pain have inconsistently demonstrated improvement in functional status in addition to pain. Furthermore, long-term trials demonstrating sustained benefit with acceptable toxicity are few.

Opioids are available in sustained-release (sustained release [SR], controlled release [CR], extended release [ER]) forms with prolonged analgesic effect lasting up to 72 hours (fentanyl transdermal), or short-acting immediate-release preparations with analgesic effect for 2 to 6 hours.48 Most opioids undergo first-pass metabolism in the liver, by oxidation involving cytochrome P-450 enzymes (fentanyl, oxycodone) and/or by glucuronidation (morphine, oxymorphone).49 Differences in opioid efficacy are partially related to genetic factors involving cytochrome P-450 alleles. Other clinically important differences in opioid metabolism are related to age, sex, and ethnicity.

Although most opioids share common pharmacologic properties and mechanisms of action, unique properties of selected agents are clinically relevant. Methadone is an effective and relatively inexpensive, long-acting opioid analgesic with unique pharmacokinetics and mechanism of action. In addition to activity at the mu-opioid receptor like other agents, methadone inhibits serotonin uptake and antagonizes the N-methyl-d-aspartate (NMDA) receptor, potentially offering superior efficacy for neuropathic pain. However, because of a disparity between duration of analgesic effect (8 hours) and drug half-life (24–26 hours), initiating treatment with methadone must be done cautiously, with increments in the dose at 5- to 7-day intervals.50 Tramadol and its active metabolite exert their analgesic effect as both mu receptor agonists and by nonopioid inhibition of serotonin and norepinephrine reuptake.49 Coadministration of tramadol with antidepressants of the selective serotonin reuptake inhibitor class risks development of a “serotonin syndrome” manifested by hyperactivity, agitation, fever, seizures, and even death.51 Finally, meperidine has a half-life of 3 hours, but the half-life of its inactive metabolite normeperidine is about 20 hours. Repeated administration of meperidine for pain relief may result in toxic levels of normeperidine, particularly in elderly patients. Clinical manifestations of normeperidine toxicity include tremors, hallucinations, and seizures.52

Several recent reviews of both short- and long-acting opioids in chronic low back pain have concluded that opioids are safe and effective, at least in the short term, in reducing symptoms.48,53,54

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