If you prefer to view this article in PDF form, click here.

Evaluation and treatment of patients with low back pain

Most back pain resolves promptly and spontaneously, and conservative treatment is effective in most cases that do not. Only in rare instances is this condition a sign of severe disease.

CPT Alan Nelson, MPAS, PA-C

Alan Nelson is on active duty with the United States Army. His background includes primary care, emergency medicine, health care administration, and PA education in civilian and military settings. He has indicated no relationships to disclose relating to the content of this article.

A commonly encountered disorder in primary and emergency care settings, low back pain (LBP) accounts for almost $20 billion in lost productivity annually in the United States alone,¹ and more than $80 billion is spent each year in the management of the disorder.² The estimated prevalence of LBP in the United States is 15% to 20% annually,³ and up to 85% of the population experiences clinically significant LBP at some point in their lives.⁴

Risk factors for chronic LBP include smoking, poor posture, and chronic misuse.¹ LBP was present in more than half of the overweight adults in one recent study on surgical management of obesity.⁵ LBP also is associated with childhood obesity.⁶ The incidence of LBP is roughly equal between the sexes.⁷

Lack of decision-making ability, poor social support, and high psychological demands on the job are specific risk factors for LBP among workers. Reducing emotional and other psychological stressors is therefore believed to have a direct and positive benefit on reducing the prevalence of LBP.^1,8 A comprehensive history and a review of systems can reveal underlying psychosocial stressors that should be addressed in the treatment plan.

In the absence of injury, diagnosing the precise cause of LBP may be challenging for health-care providers. In the majority of patients presenting with LBP, no specific anatomic or physiologic defect is identified other than a presumptive soft tissue strain or sprain.² Most patients recover quickly with little or no long-term disability; more than 90% of episodes resolve spontaneously within 4 weeks, and only 5% of patients with LBP are disabled longer than 3 months.⁹

ANATOMY AND PHYSIOLOGY

The lumbar spine is an elegant structure with a complex local supporting system. Unlike the thoracic spine, it lacks the stabilizing strength provided by associated ribs. In acute LBP, a strain may occur in one or more of the supporting soft tissue structures,¹⁰ such as the linear arrangements of erector spinae muscles (see Figure 1). However, the numerous ligamentous structures that act within and between the spinal segments are thought to be the actual sites of injury in most cases of LBP.¹⁰ Local muscle spasms that occur secondarily are often the primary finding on physical examination.

The intervertebral disks represent another potential site of pathology. These structures essentially act as shock absorbers, preserving the anatomic interspace between the vertebral segments. The gelatinous nucleus pulposus, or core of a disk, may traumatically or chronically herniate through its surrounding fibrous capsule, the annulus fibrosus. This herniation may then impinge on nearby spinal nerve roots, creating local and/or radiating symptoms. This pathologic process must be ruled out in patients presenting with radiating symptoms.

DIFFERENTIAL DIAGNOSIS

Patients with LBP present at different points in its genesis, with symptom severity and effects on quality of life a major factor in the timing of presentation. LBP of up to 4 weeks’ duration may be considered acute because of the relatively slow recovery experienced by some patients, most of whom nonetheless suffer no permanent sequelae. Episodes of LBP lasting longer than 12 weeks are generally considered chronic.¹¹ As when treating many medical conditions, the clinician must differentiate benign etiologies from more severe underlying disease. A reasonable differential diagnosis is provided in Table 1.

Patients presenting with LBP as their primary complaint can be divided into three broad groups.¹⁰

• The smallest but most worrisome group has LBP as a consequence of a potentially serious and often occult condition, such as a neoplasm.
• In the absence of identified anatomic or physiologic abnormalities, terms such as nonspecific back pain or mechanical back pain may be used to describe the symptoms experienced by most patients. These are diagnoses of exclusion consistent with a presumptive soft tissue strain or sprain.¹¹ This second group of patients often present with a history of an acute injury from an unsafe lifting practice or a history of repetitive overuse. They usually deny radiation of pain.
• The third group is the approximately 4% of patients with acute LBP who have radiating sensations to the lower extremities secondary to nerve impingement.² Radiating sensations can include pain, numbness, weakness, or paresthesia. Sciatica is the common term for this symptom cluster. Sciatica may be more accurately termed radiculopathy when occurring in a distribution consistent with the sensory pattern of one or more spinal nerves. Radiculopathy is approximately 95% sensitive for some process that affects the nerve roots, including a herniated disk.¹¹ These symptoms are particularly diagnostic when reproduced with the straight leg raise (SLR) test.

Radiculopathy may occur as a result of compression of nerve roots at the spine or more distal nerve irritation at the pelvic level, such as sciatic nerve irritation. Sciaticalike pain that does not radiate below the knee on SLR test may be due to tight hip and thigh muscles. Clinicians must keep in mind that only 1% to 3% of patients with acute LBP will have a herniated disk.¹¹ Establishing the presence or absence of true lumbar spinal radiculopathy is a key focus of the evaluation of patients with LBP.

Even when LBP is consistent with a minor soft-tissue strain, it can be severely painful, occurring with associated spasms that may remarkably limit functional capacity. Patients may be particularly concerned about the level of pain, which seems to them to indicate a serious problem. Where appropriate, patients can be reassured that LBP episodes typically resolve without permanent sequelae. However, recurrence is common, and education about careful lifting methods is in order.

PATIENT EVALUATION

The history and physical examination remain the primary tools for assessing patients with LBP because most patients will not demonstrate appreciable findings on imaging or other studies such as laboratory tests. The history is possibly more useful than the physical examination in ruling out occult serious disease. In obtaining the history of a patient’s LBP, clinicians will find the “OPQRST” approach beneficial in outlining key symptomatic parameters (see Table 2). There are well known key indicators that increase suspicion of worrisome diagnoses (see Table 3). Elderly patients complaining of new-onset LBP without injury, especially those with a history of any type of malignancy, are at increased risk of metastatic disease—or even of primary neoplasm—as the underlying cause of their pain.²

The review of systems is useful in ruling out nonmusculoskeletal problems such as urinary pathology, a significant cause of back symptoms. Negative responses to inquiries about dysuria, hematuria, fever, or changes in urinary frequency reduce the likelihood that laboratory evaluation will be initially required. When indicated, urinalysis and urine cultures assist the clinician in ruling out infection.

Inspection of the exposed torso is a key initial step in physical examination. Obvious deformities such as scoliosis (lateral curvature of the spine) or kyphosis (exaggerated anterior/ posterior convexity of the spine) are often appreciable via direct visualization of the patient while he or she is standing erect and when flexed at the hip. Palpation of the spinous processes will confirm lateral curvature in scoliosis. Tight, spasmodic paravertebral muscles are often present on palpation in cases of lumbar strain. Also, the clinician must examine and document the patient’s active range of motion. Tenderness on percussion of the spinous processes should rule out spinal neoplasm.

The SLR test, also called Lasegue’s test, is useful in identifying true nerve root compression. It should be performed on most patients with LBP, particularly when sciaticalike symptoms are described. The supine test is performed as the examiner gently raises one extended leg at a time, lifting at the ankle. A positive test, indicating possible nerve-root compression, occurs when the patient feels radiating pain down the leg (usually the lateral or posterior aspect) at less than 70 degrees of hip flexion. Aggravation of the pain with ankle dorsiflexion and relief with knee flexion support the positive finding.

Performance of the SLR test with the patient seated may create fewer false positives than when the patient is supine.² Patients with no pain while sitting with the leg(s) extended, but who describe pain on supine examination, can be suspected of having a psychogenic origin for their pain, such as malingering.¹²

Diagnostics Whether to obtain plain radiographs of the lumbar spine remains a key question for many clinicians. In cases of trauma, plain films are usually warranted. When taken on initial evaluation of the patient with no history of trauma, however, radiographs confer few if any differences in average patient outcomes at 6 weeks and 1 year.¹³ Interestingly, patients may actually be happier with their care and less likely to seek further care if told they have simple degenerative joint disease as seen on plain film.¹³

An abdominal kidneys-ureters-bladder radiograph or a renal colic CT series will assist in ruling out urinary calculi. Hydronephrosis can be seen on these studies if there is an obstructing lesion. CT may reasonably be considered the gold standard for the evaluation of urinary calculi,¹⁴ and urolithiasis is the primary indication for CT in the evaluation of LBP. Pancreatitis may create abdominal pain radiating to the back and requires laboratory testing of amylase and/or lipase levels, as well as CT imaging. Aortic aneurysms likewise may cause LBP and can be visualized with ultrasonography or CT.

MRI is a revolutionary tool for assessing spinal complaints, a result of its ability to assess the relevant anatomy in great detail.¹⁵ However, when imaging is indicated in the acute setting, plain radiographs are preferred. Whether patients present with or without radicular symptoms, rapid evaluation with MRI has no proven advantage.¹⁶ When MRI has been readily available for the acute evaluation of LBP, its use has been correlated with higher health care costs and greater numbers of surgical procedures, without measurable improvements in patient outcomes.¹⁷

In the evaluation of chronic back pain, recurrent back pain, or back pain with suspected disk abnormalities, MRI will confirm or rule out anatomic defects of the spine and associated structures. Disk pathology is one of the most common problems identifiable on MRI. Both plain radiography and MRI are beneficial in ruling out bony malignancies, which are often visualized on plain film because of the radiopacity of healthy bony tissue.

TREATMENT

As stated, the prognosis for the average patient with LBP is quite favorable. However, the clinician should attempt to promptly determine the optimal treatment course to prevent progression to chronic LBP.

Rest Adequate sleep is both a challenge for LBP sufferers and an essential step in recovery. At least 6 to 8 hours of restful sleep per night is recommended to promote spinal relaxation. Supporting cushions at the lumbar area or below the knees may improve the odds of rest.¹ In the absence of known serious etiologies or pronounced disability, maintaining reasonable levels of physical activity to patient tolerance is probably better than bedrest.⁹ For more serious cases, such as those involving herniated disks, most studies show similar outcomes for either bedrest or continued activity to tolerance.¹⁸

Patients with LBP must avoid known strenuous, pain- precipitating activities such as heavy lifting or repetitive motion and should resume full activity gradually. This is especially important in occupational medicine, a specialty in which LBP is highly prevalent. Obtaining an accurate idea of precipitating factors and ensuring compliance with workload restrictions are often difficult for health care providers in occupational medicine. Factors that contribute to these challenges include employer expectations, job-specific activity requirements, patient reporting of workloads, and patient motivation levels.

Medication Adequate pain management is a generally accepted humane approach. Analgesics and muscle relaxants are the treatments of choice for LBP.¹ Analgesics such as OTC and prescription NSAIDs are commonly used, as are stronger medications such as hydrocodone and oxycodone. Muscle relaxants, such as cyclobenzaprine or methocarbamol, are widely-prescribed as adjunctive therapy; however, objective data verifying their usefulness appears lacking.

Clinicians should approach opiate-based medical therapy carefully, ensuring that patients with benign etiologies understand the likely limited course of their ailments regardless of treatment. Patients with LBP are at significant risk of self-overmedication, with approximately 27% of chronic LBP patients demonstrating analgesic overuse.¹⁹

Patient self-care The application of heat and/or cold may be efficacious for patients experiencing LBP. Some clinicians suggest initial use of cold compresses followed by a gradual transition to heat. Alternating heat and cold may assist in reducing muscle tension in cases of stubborn spasms. In subacute and chronic LBP, patients may get more benefit from applying heat. Patients should limit contact time with either temperature extreme to avoid tissue damage. In general, these modalities must be individualized. Patients should cautiously perform stretching exercises and incorporate abdominal strengthening exercises into their personal fitness program.

Injection therapy The injection of an anesthetic into the site of persistent muscle spasms, often referred to as trigger point injection, is widely performed at the primary-care level with anecdotal benefits and probably needs further study. It was stated to be of proven benefit in reducing symptoms and was associated with positive outcomes in studies from the 1990s. However, more recent meta-analysis of these trials has revealed a paucity of true randomized, placebo- controlled inquiry.²⁰

Direct corticosteroid injection into diseased intervertebral disks has not been proven beneficial.²¹ However, deep-tissue injections administered by specialists can be effective for certain patients. These include epidural injections and injections into areas of known inflammation such as the sacroiliac and facet joints. Referrals to specialists need not indicate to patients that surgery will be required.

Surgery The role of the surgeon in the treatment of mechanical LBP appears limited. Most studies comparing surgical and nonsurgical treatments focus on very specific and serious cases, such as those requiring spinal fusion.¹⁴ It is generally accepted that imaging-verified anomalies such as bulging or herniated disks and failure of all available conservative management are reasonable criteria for referral to an orthopedic specialist for either nonsurgical or surgical treatment.

Support devices In routine cases, lumbar-support devices such as corsets are unlikely to produce outcomes any different from providing no treatment at all.⁹ Data appears mixed as to whether there is any advantage to providing workers with lumbar-support devices for protective use on the job. Such devices may serve solely as physical reminders to use a safe technique when lifting.

Other therapeutic modalities Referral for physical therapy (PT) is a common choice in LBP management. PT is often seen as the next step for the patient who proves unresponsive to medical management but whose condition does not yet appear to warrant surgical management. PT for LBP includes hot and cold modalities, ultrasound, electrical stimulation, and structured exercise and stretching programs.

Spinal manipulative therapy may be employed by chiropractors, osteopathic physicians, and others. These techniques may be as effective as analgesics, PT, and other forms of primary-care level treatments but are not proven superior to them.²² Massage therapy has also been shown to provide positive results in terms of patient outcomes and cost of care.^22,23

CONCLUSION

Familiarity with the management of patients with LBP remains important because the problem is common and may become more so as obesity prevalence increases in the United States. Clinicians in any primary care setting must individualize treatment to the patient. With careful attention to the history and physical examination and judicious use of imaging where indicated, most cases can be effectively managed with conservative therapy. Referral remains a reasonable option for serious and unresponsive cases.

REFERENCES

© 2007 Haymarket Media, Inc. and the American Academy of Physician Assistants. All rights reserved.
Use of jaapa.com subject to License agreement. Please read our Disclaimer and Privacy policy.