Low back pain

COMMON MEDICAL PROBLEMS IN AMBULATORY CARE

0025-7125/95 $0.00

+ .20

LOW BACK PAIN Joyce E. Wipf, MD, and Richard A. Deyo, MD, MPH

Low back pain is a common patient complaint requmng highly selective evaluation based on the history, risk factors, and findings on examination. Patients must be carefully evaluated before spine radiographs and imaging scans are obtained because the mere presence of abnormal anatomic findings on these studies may not indicate the true cause of pain and could subject patients to unnecessary additional tests, treatments, and surgery. Most patients with low back pain cannot be given a definitive diagnosis owing to a loose association among symptoms, physical examination, imaging tests, and anatomic findings. 2 • 1~ Therefore, low back pain should be considered as a symptom rarely attributable to a specific disease or a pathologic lesion. Back pain ranks second only to upper respiratory infection as a reason for physician visits and is the leading reason for visits to orthopedic surgeons and neurosurgeons. Up to 90% of adults experience back pain at some time in their lives. 40• 53 Pain resolves with nonspecific treatment within 6 weeks in 75% to 90%, although recurrences are common. 23 About 2% of patients have associated lower extremity nerve root symptoms (radiculopathy) that persist beyond 2 weeksY There is little consensus among or within specialty groups regarding the use or timing of diagnostic tests. There is ample evidence that plain spine radiographic films, computed tomography (CT), and magnetic resonance (MR) imaging show abnormalities in 20% or more of "normal" persons without back pain. 3 • 37, 62 Nonselective ordering of these studies in patients with low back complaints may lead to a misunderstanding that such coincidental abnormalities are the cause of pain. Clinicians should reserve such studies for patients with signs and symptoms of radiculopathy that are unresponsive to conservative care or for those with risk factors for serious systemic disease. From the Department of Medicine, University of Washington; Resident Ambulatory Training Program, Seattle Veterans Affairs Medical Center (JEW); and Robert Wood Johnson Clinical Scholars Program (RAD), Seattle, Washington MEDICAL CLINICS OF NORTH AMERICA VOLUME 79· NUMBER 2· MARCH 1995

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Annual medical costs for low back pain are estimated to be as high as $24 billion. 5 , 12, 25 If disability and loss of work productivity are included, estimates of total annual cost owing to low back pain approach $50 billion. Annually, 2';10 of all American workers have a compensable back injury, and 14% lose at least 1 work day per year owing to low back pain. 40 Back surgery is done more frequently in the United States than in any other country. 53 Although there was wide geographic variation, rates of surgery for low back pain in the United States increased 55% from 1979 to 1990. Surgery for spinal stenosis quadrupled during the same time period. One percent to 2% of American adults have had back surgery, despite the recommendation by experts for selective use of surgery and the poor success rate of multiple surgical operations in alleviating pain. 12, 49, 58 The majority of patients seen in back clinics for chronic pain have undergone at least two operations. 46 ANATOMY OF THE SPINE

In the normal spine, the anterior vertebral bodies and their interconnecting disks provide weight bearing and shock absorption. The spinal cord and nerve roots are protected by the posterior elements, including the vertebral arches, transverse and spinous processes, and facet joints. The facets, ligaments, and paraspinal muscles provide stability and balance. Pain may arise from nearly any of these structures, but the precise source is often not identifiable. The intervertebral disk begins to deteriorate by about age 30. With cracking of the outer annulus, the gelatinous inner nucleus pulposus of the disk can protrude, causing irritation or compression of adjacent nerve roots. 16 ,64 Gradually the nucleus pulposus becomes fibrotic and is less likely to herniate in older individuals. Intradiskal pressures vary with position and increase with cough or straining. 45 Because pressures are highest with bending and sitting, supine or upright standing positions are recommended for management of acute pain. lO DIFFERENTIAL DIAGNOSIS Classification

Low backache complaints may be categorized in most individuals as simple back pain, when there are no risk factors or signs of underlying pathology.14 Most cases of simple back pain are of nonspecific origin and are often attributable to mechanical factors. A careful history identifies patients with complex back pain, These individuals have increased risk for underlying medical conditions and need further workup with laboratory tests and plain radiographs. Risk factors for a secondary cause of back pain include age over 50 years, history of cancer or intravenous

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drug use, signs or symptoms of systemic disease (e.g., fever, weight loss, lymphadenopathy), and sciatica or neurologic deficit on examination. Although a third of primary care patients have such risk factors, 95% ultimately have normal laboratory and radiographic studies. 14 Sciatica occurs in 2% to 3% of patients with low back pain and can be defined as pain radiating into the buttock and down the leg below the knee, often with numbness extending into the lower leg and foot. 16 Sciatica is the symptom complex seen with radiculopathy, or nerve root compression, and therefore pain and neurologic symptoms should folIowa dermatomal distribution (Fig. 1).22 Far fewer than 1% of all patients

Figure 1. Lower extremity dermatomes. (From Finneson BE: Low Back Pain, ed 2. Philadelphia, J.B. Lippincott, 1980, p 52; with permission.)

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presenting with back pain have acute radiculopathy with urinary retention, saddle anesthesia, bilateral symptoms, or bilateral neurologic examination deficits. These findings, however, are suggestive of cord compression or cauda equina syndrome and require urgent neurosurgical referral.

Systemic Causes

The most common medical diseases causing low back pain are malignancy and infection.!4, 60 Vertebral compression fracture should raise the suspicion of cancer. Malignancy is most often due to metastatic carcinoma from breast, lung, or prostate, but other causes include multiple myeloma, lymphoma, leukemia, and primary spinal cord or extradural tumors. Infection should be suspected in any patient with fever and backache and may be due to endocarditis, vertebral osteomyelitis, diskitis, or epidural abscess. The most likely infecting organism is Staphylococcus aureus, but elderly individuals and drug abusers commonly have gram-negative osteomyelitis. 60 Mycobacterium tuberculosis has a predilection for the anterior elements of the lower thoracic or upper lumbar vertebrae (Pott's disease). An abdominal examination should be performed in patients over age 50 or those with known coronary artery disease. Abdominal aortic aneurysm may present with chronic or acute back pain, and pain from leaking aneurysms may also radiate into the scrotum or leg. 63 Other medical causes of back pain include primary renal, gastrointestinal, or pelvic disease.

Rheumatologic and Structural Conditions

Inflammatory arthropathies, such as ankylosing spondylitis, are characterized by onset usually by age 40, symptoms on awakening, and improvement with activity.2!,27 Similar features may be seen in psoriatic arthritis, Reiter's syndrome, and arthritis associated with inflammatory bowel disease. Osteoporosis, which is common in older patients or those on long-term steroid therapy, may cause pain owing to bulging disks or compression fractures. Spondylosis refers to disk space narrowing and arthritic changes of the facet joint. It is often seen at multiple levels and is equally prevalent in asymptomatic and symptomatic older individuals. Spondylolithesis is the forward displacement of one or more lumbar vertebrae; minor slippage is usually an incidental finding and is asymptomatic. Marked slippage of 75% to 100% of the vertebrae may cause radicular symptoms. Sacralization of the fifth lumbar vertebra or lumbarization of the first sacral vertebra are common normal variants and generally not a source of pain. 45

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Vertebral Disk Herniation

Herniation of the disk occurs at the L4-5 or L5-S1 levels in more than 95% of cases. 16,24 Herniation of L4-5 (L-5 root) causes pain and numbness radiating from the back to the posterior thigh, anterolateral leg, medial foot, and great toe (see Fig. 1).22 Examination may show foot and toe weakness on dorsiflexion and a footdrop. Reflexes are preserved. L5-S1 disk herniation (S-l root) presents with pain and numbness of the posterior thigh and leg, posterolateral foot, and lateral toes. Plantar flexion of the foot and toes may be weak, and there may be difficulty walking on the toes owing to peroneal muscle weakness. The Achilles tendon reflex may be decreased. Herniation occurs at the L2-4 level in 2% to 5% of patients and presents with pain and numbness of the posterolateral or anterior thigh radiating down the anteromedial leg. Weakness on knee extension owing to quadriceps muscle weakness and a decreased knee reflex are seen with compression of the L-3 or L-4 nerve roots. Compression of the cauda equina usually is caused by massive midline disk herniation. Patients with the cauda equina syndrome typically present with back pain, urinary retention, and bilateral leg numbness. Three fourths of patients have saddle anesthesia of the perineum and posteromedial thighs, which are innervated by S-3 and S-4. Similar presentation occurs in spinal cord compression caused by malignancy or infection. Emergent surgical consultation is required in patients with progressive neurologic deficits or suspected compression of the cauda equina or spinal cord.

Spinal Stenosis

Nerve root entrapment from spinal stenosis usually develops from hypertrophy of the facet joints and ligamentum flavum and subsequent narrowing of the canal; less commonly the canal is congenitally narrowed. 30, 38, 44 Patients often present with back pain and transient numbness that worsen with walking. This is termed pseudoclaudication or neurogenic claudication because of similarities to vascular claudication. 31 , 38 In neurogenic claudication, however, patients have normal arterial pulses, and there is less consistency in the distance to claudication. After rest, pain usually lasts for 10 to 15 minutes in neurogenic claudication versus 5 minutes in cases of vascular claudication?l Patients usually give a history of back pain preceding neurogenic claudication and sometimes have a dermatomal distribution of sensory deficit, abnormal straight leg raising (SLR), and muscle weakness. A wide-based, unsteady gait is also common. Symptoms are usually relieved by sitting and aggravated by standing erect or extending the spine. This contrasts with patients who have a herniated disk, for whom flexion (sitting) exacerbates pain and standing erect is more comfortable.

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PHYSICAL EXAMINATION IN LOW BACK PAIN

For individuals with simple back pain, a focused examination is sufficient. This consists of spinal examination and selective screening for sensory, motor, and reflex function of the lower extremities. l7 The back examination includes range of motion and inspection for ana to mic deformities, such as scoliosis and kyphosis. Range of motion assessments may be helpful in monitoring response to therapy. Forward flexion is the most common limitation, and the degree of flexion limitation is reliably reproduced. Patients with spinal stenosis may show pain on extension. Interobserver agreement regarding the presence and location of paravertebral muscle spasm is poor. 57 Patients with pain persisting for several weeks and those with risk factors for systemic disease should have a general screening examination, including examination for malignancy and adenopathy. Patients with back pain and radicular symptoms require careful neurologic examination of the lower extremities to confirm the abnormality and identify the level of nerve root compression. 17, 59 Neurologic testing should focus on L-5 and S-l nerve root function. The maneuver of SLR can help to confirm the radiculopathy.29,35 The test is performed with the patient in the supine position and the examiner raising the extended leg. A positive SLR test reproduces sciatica or back pain when the leg is elevated between 30 and 60 degrees. Limitation of ipsilateral SLR is moderately sensitive but not specific, and crossed SLR (sciatica precipitated in the affected leg by raising the unaffected leg) is nonsensitive but highly specific for a herniated disk 39,63

DIAGNOSTIC TESTS Laboratory Tests

Most laboratory tests are nonspecific and minimally useful in the evaluation of low back pain. In cases of simple back pain, no laboratory studies are necessary. Although it is nonspecific, an erythrocyte sedimentation test is the most sensitive screening test to detect serious systemic or rheumatologic diseases in patients with risk factors,14 Peripheral white blood count is indicated when infection is suspected, Other laboratory tests, such as urinalysis, should be tailored to the diagnoses suggested by the history and physical examination. The HLA-B27 histocompatibility antigen should not be used as a screening test for ankylosing spondylitis because of the antigen's moderately high prevalence in the normal population. The HLA-B27 antigen is found in about 6% of the general population, whereas the prevalence of ankylosing spondylitis is well under 1%,17 Unless the diagnosis of ankylosing spondylitis is equivocal clinically and radiographically, the test is generally not needed for confirmation,

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Plain Radiographic Films

Ordering multiple-view series lumbar spine films is costly and often unnecessary but is often done in the evaluation of patients with low back pain. ll , 45 Because there is a poor relation between radiographic abnormalities and symptoms, simple back pain does not require further screening tests. ll , 46 For patients with complex low back pain and risk factors, plain radiographic films may be helpful in identifying destruction of the vertebrae or surrounding structures owing to infection, mass, or tumor. Several studies suggest that the anteroposterior and lateral views are sufficient in the initial evaluation of complex low back painY The prevalence of radiographic anomalies, such as facet joint abnormality, degenerative disk disease, spondylolysis, and spina bifida occulta, is similar in patients with and without pain, and 20% or more show facet or disk abnormalitiesY' 36 Although many patients have come to expect radiographic films in the assessment of their back pain, they would be just as satisfied with a careful explanation of their prognosis and why the radiographic studies are unnecessary.63

Magnetic Resonance Imaging or Computed Tomography Scanning

The availability of eT and MR imaging scanning has complicated the assessment of back pain because of the high prevalence of abnormalities in normal subjects with no history of low back pain or sciatica. 33,64 Twenty percent of asymptomatic persons under the age of 40 and 27% of those over age 40 have herniated disks apparent on eT scans. 62 MR imaging scans demonstrate herniated disk in a quarter of asymptomatic persons under age 60 years and one third of those over age 60. Prevalence of spinal stenosis in normal subjects also increases with age and is seen on MR imaging in 20% of persons over age 60. 3 Because the term disk herniation is ambiguous, one MR imaging study classified disks as bulging, protruding, or extruding. 3 ? Bulging or protruding disks were highly prevalent in asymptomatic subjects (Table 1). Extruding disks, defined as more extreme extension beyond the interspace, were seen in 1% of asymptomatic and 7% of symptomatic persons. Only 36% of those examined had a normal disk at all levels. Although these abnormalities are probably real, they cause no clinical problems in these asymptomatic persons. For clinical decision-making purposes, therefore, they can be considered false-positive findings. 2,8 Owing to their high false-positive rate and increasing prevalence of abnormalities with age, eT and MR imaging scans must be selectively ordered. They should be reserved for patients with clinically suspected malignancy or infection or for those who become surgical candidates because of persistent or progressive radiculopathy. MR imaging and eT have largely replaced myelography in the workup of low back pain.

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Table 1. PREVALENCE OF BULGES, PROTRUSIONS, AND EXTRUSIONS ON MAGNETIC RESONANCE IMAGING SCANS IN 98 ASYMPTOMATIC SUBJECTS AND 27 SYMPTOMATIC SUBJECTS No. Subjects (%) Bulge Evaluator 1 Asymptomatic subjects Symptomatic subjects Evaluator 2 Asymptomatic subjects Symptomatic subjects Average of the two evaluators Asymptomatic subjects Symptomatic subjects

Protrusion

Extrusion

52 23

(53) (85)

30 14

(31) (52)

2 (2) 8 (30)

50 18

(51 ) (67)

23 15

(23) (56)

0 6 (22)

26.5 (27) 14.5 (54)

1 (1) 7 (26)

51 (52) 20.5 (76)

From Jensen MC, Brant·Zawadski MN, Obuchowski N, et al: Magnetic resonance imaging of the lumbar spine in people without back pain. N Engl J Med 331 :70, 1994; with permission.

Bone Scanning

Radionuclide bone scanning is relatively nonspecific and should be used selectively in the evaluation of low back pain. Bone scanning is most helpful when clinical findings or erythrocyte sedimentation rate supports a diagnosis of malignancy but plain films are normal or to rule out osteomyelitis when radiographs are nondiagnostic. Bone scans are more sensitive for early disease and may show fractures earlier than plain films. In patients with compression fracture, which is likely to appear on plain film, or with lytic or blastic lesions seen unequivocally on radiographic film, bone scan is unnecessary for diagnosis. True positive findings on bone scan are rarely seen when plain radiographs and the erythrocyte sedimentation rate are both normal,5o Electromyelography

When the neurologic examination is equivocal for radiculopathy, electromyography (EMG) and nerve conduction studies may confirm the presence and level of nerve root involvement. These tests are ordered earlier and more frequently by neurologists and by physical medicine and rehabilitation specialists. 6 EMG is not indicated for simple low back pain. In patients with low back pain and clear clinical evidence of radiculopathy, EMG is not likely to contribute much new information to CT or MR imaging results. EARLY DIAGNOSTIC STRATEGY

Clinical assessment of the patient with low back pain determines whether further diagnostic evaluation or conservative therapy with ob-

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servation is most appropriate (Fig. 2).63 Situations necessitating emergent surgical referral include acute severe radiculopathy; progressive or bilateral neurologic deficits; or associated bladder findings, usually urinary retention. Patients with unilateral radiculopathy and stable neurologic examination can receive more selective evaluation, based on the clinical response to conservative management.

THERAPY Simple back pain has an excellent prognosis with conservative therapy. Eighty percent of patients show improvement or resolution of LOW BACK PAIN WITHOUT SCIATICA

Simple back pain (60%) Age under 50 No signs or sx of systemic disease No hx of cancer Nonnal neuro exam

LOW BACK PAIN WITH SCIATICA

Back pain with risk factors (37%)

Radiculopathy (3%)

Urgent situations

Age over SO Systemic signs, sx or risk factors: fever, weight loss, hx prior cancer, hematuria, adenopathy, IV drug use

Signs and sx of unilateral radiculopathy, No bladder sx

Acute radiculopathy with urinary retention, saddle anesthesia, bilateral neurologic sx or exam findings

t

<99% probability of

(1-10% probability of musculoskeletal cause) systemic disease)

Plain film and ESR

No diagnostic tests Start conservative therapy for 4-{; wks

If nonnal, conservative therapy for 4-{; wks unless neurologic deficit progressive

IMPROVED

STOP

NOT IMPROVED

,

Plain film and ESR IF either abnonnal, consider bone scan Close follow-up is warranted

/

IMPROVED

STOP

«1%)

!

Urgent consultation and er or MRI to evaluate for cord or cauda equina compression

NOT IMPROVED

Noncontrast er or MRI, or electrodiagnostic tests; choice depends on local availability and skills of clinician and radiologists

Figure 2. Diagnostic strategy for evaluation of low back pain. (Modified from Wipf JE, Deyo RA: Low back pain. In Branch WT (ed): Office Practice of Medicine, ed 3. Philadelphia, W.B. Saunders, 1994, p 654.)

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symptoms by 4 to 6 weeks. Patients need education and reassurance that they do not have a disabling condition. About half of patients with sciatica recover by 6 weeks, and most do not require surgical intervention. 22 ,24 Surgery is most appropriate for patients with persistent or progressive neurologic deficits and those with disabling sciatica caused by disk herniation. Restrictions on Physical Activity

Early return to physical activity and moderate exercise is beneficial in patients with low back pain. Older recommendations of prolonged bed rest and missed employment are actually harmful, not only in contributing to slower recovery but also in reinforcing the patient's selfperception of disease and disability. Patients should be encouraged to return to work early, even if in a limited capacity. In a study of acute low back pain without radiculopathy, outcome after 2 days of bed rest was compared with outcome after 7 days of bed rest. IS Functional status and pain were similar in both groups at 3 weeks and 3 months, but shorter bed rest resulted in 45% fewer days of work lost. Another study randomizing patients to 4 days of bed rest or no bed rest did not find any detectable difference in symptom duration or rate of resolution. 26 The patients without any bed rest, however, reported a return to their normal level of activity 48% sooner than those with 4 days of bed rest. Patients without radiculopathy or neurologic deficits should be given brief, if any, bed rest for back pain. There are no similar studies of activity level in patients with back pain and radiculopathy, but strict supine bed rest for a few days may reduce intradiskal pressure in patients suspected of disk herniation. Bed rest should generally be for less than 1 week to avoid loss of muscle mass and bone density. Furthermore, upright posture produces intradiskal pressures only slightly higher than the side-lying position. 4s Exercise and PhYSical Treatments

Back exercises and general fitness programs are probably beneficial in the therapy of back pain and the prevention of recurrent episodes, although the optimal regimen is unclear. Clinical trials suggest that flexion exercises are of little efficacy for acute back pain and may be associated with worsening symptoms. 26 Benefit has been shown from rigorous extension exercises and milder stretching exercises, particularly in patients with chronic pain or recurrent episodes of pain. IS, 42 If back pain persists beyond 6 to 8 weeks, physical therapy referral may be helpful for teaching an exercise program and improving patient compliance. Transcutaneous electrical nerve stimulation (TENS) has a substantial placebo effect but appears to have little if any effect on functioning. IS, 32

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Acupuncture may subjectively improve pain, although studies comparing true acupuncture at appropriate body sites with misplaced needling have not shown this. 9 Lumbar traction and orthotic devices for low back pain are popular therapies with no demonstrated efficacy, including several negative trials of traction. 16, 52 Medications

Multiple nonsteroidal anti-inflammatory agents have demonstrated efficacy for symptomatic relief of low back pain. Most of these have similar efficacy and risk of side effects, and selection of agent depends on provider preference and cost. There are some clinical trials of muscle relaxant use, but patient selection remains unclear, and these drugs carry a risk of dependency if used over a long-term period. Tricyclic antidepressants are commonly used in patients with chronic back pain, but their efficacy has not been convincingly demonstrated. 54 Injection Therapies

Corticosteroid injections into the facet joints have become widely used and are considered safe but are costly and of little value compared with saline injections in randomized trials of chronic pain. 4 Steroid injections into trigger points also have no proven benefit. For patients with sciatica, the use of epidural steroid injections remains controversial, but several randomized trials suggest a modest benefit. Surgery

The rates of laminectomy and lumbar spine surgery in the United States have continued to rise, despite an extensive literature on failed surgery and recommendations for more selective intervention. 12, 34, 49, 58 Back surgery rates in the United States are twice those of most developed nations and five times that of Great Britain. 5 Higher surgical rates are associated with a higher per capita supply of orthopedic and neurosurgeons in the country. Regional variations within the United States, with surgery rates highest in the South, appear related to individual surgeon training and practice style and not to medical access or rates of compensation claims. 56 Clinical presentation should dictate the need for surgical evaluation. General consensus exists about indications for surgical referral of patients with sciatica (Table 2).16 One nonrandomized outcome study of surgery versus conservative care of myelographically proven herniated disk found more rapid improvement of symptoms 2 months after surgery than after conservative care (97% versus 89%).30 By 3 months,

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Table 2. INDICATIONS FOR SURGICAL REFERRAL IN THE PATIENT WITH SCIATICA The cauda equina syndrome (a surgical emergency): characterized by bowel and bladder dysfunction (usually urinary retention), saddle anesthesia, bilateral leg weakness and numbness Progressive or severe neurologic deficit Persistent neuromotor deficit after 4-6 weeks of conservative therapy Persistent sCiatica, sensory deficit, or reflex loss after 4-6 weeks in a patient with positive straight leg raising sign, consistent clinical findings, and favorable psychosocial circumstances (e.g., realistic expectations and no evidence of depression, substance abuse, or excessive somatization) From Oeyo RA, Loeser JO, Bigos SJ: Herniated lumbar intervertebral disk. Ann Intern Med 112:598603, 1990; with permission. The Annals of Internal Medicine is not responsible for the accuracy of the translation.

complete resolution occurred in 90% of those with surgery compared with 76% without surgery. Data from a randomized trial showed satisfactory results 1 year after lumbar disk herniation in 92% treated surgically and 79% receiving medical treatment. 61 At 4 years, satisfactory results were reported in 82% of those with surgery and 88% of those treated nonsurgically. Relapse had occurred at 4 years in 15% of the surgery group and 24% of the medical group. Recovery of motor weakness is more rapid after surgery than with conservative care but total recovery rates are similar by 4 years. 34,61 Surgery appears be more helpful in resolution of radicular symptoms than back pain. Improvement of sciatica also occurs earlier with chemonucleolysis than with medical therapy, with improvement by 6 months in 78% compared with 42% without chemonucleolysis. lO Motor weakness resolved by 6 weeks in 82% of those receiving chemonucleolysis and 66% of those receiving conservative care. Several small randomized trials, however, suggest that conventional surgery is superior to chemonucleolysis. 34,47 Spinal stenosis is frequently treated surgically, but rigorous data on indications for surgery or the natural history of spinal stenosis are lacking.1O,23, 30,55 A systematic literature synthesis of surgical outcomes for spinal stenosis found 13% of patients had a surgical complication and 64% of patients had good-to-excellent results. 55 Spinal Manipulation

Chiropractic manipulation, the most common type of spinal manipulation, accounts for a significant portion of health care costs for back pain. Data on outcomes and complications of manipulation are slowly emergingy,51 Several controlled trials have shown short-term benefit in patients with acute low back pain but negative results in those with sciatica or chronic pain?' 28,43 In one study, functional status was improved by manipulation at 1 to 4 weeks after onset of pain, but by 6 weeks, outcomes were similar among treatment groups. 51 Serious complications with lumbar manipulation appear to be rare, with most

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arising from delay in diagnosis and treatment of unrecognized malignancy. Death or paraplegia from meningeal hematoma have been reported. 51 Development of cauda equina syndrome after spinal manipulation in patients with sciatica is rare, and half of those cases in one series occurred with manipulations done under either anesthesia or narcosis. Education

Patients deserve information regarding the favorable prognosis for low back pain. Most patients have excellent recovery even if radiculopathy or disk herniation is present. Neutral terms such as backache or protruding disk reduce the patient's fears about severe disease or disability, whereas ruptured disk and degenerative spine may be frightening. Because back pain is more frequent in persons who are sedentary, obese, or smokers, risk may be reduced by lifestyle changes. 2o EMPLOYMENT SCREENING

Despite the enormous impact of low back disability on industry, there are no patient characteristics or screening tests that accurately predict which individuals are likely to sustain injury or develop complaintsy,23 Work conditions that require lifting, twisting, or vibratory movements are risk factors for back pain. Neither screening radiographs nor training in lifting techniques has been shown to prevent occupational back problems. 1 SUMMARY

Low back pain is a common reason for physician visits and is associated with enormous costs to health care and industry. Radiographic abnormalities of the lumbar spine, including disk protrusion, are common in asymptomatic subjects and only loosely associated with symptoms and neurologic examination. Therefore, highly selective evaluation is required to avoid subjecting patients with back pain to unnecessary tests and surgical procedures. Reassurance about the favorable prognosis of low back pain is an important component of therapy. Most patients with simple back pain recover with symptomatic treatment. Plain radiographs are indicated for evaluation of patients with radiculopathy and those with risk factors for underlying medical conditions. The majority of patients with back pain, even those with radiculopathy, improve with conservative management and surgery is unnecessary. Surgical consultation and eT or MR imaging scans are indicated for patients with persistent or progressive neurologic deficits or persistent sciatica with nerve root tension signs. Acute radiculopathy with bilateral neurologic deficits, saddle anesthesia, or urinary symptoms is suggestive

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of cord compression or cauda equina syndrome and requires urgent surgical referral. References 1. Bigos SI, Hansson T, Castillo RN, et al: The value of preemployment roentgenographs for predicting acute back injury claims and chronic back pain disability. Clin Orthop ReI Res 283:124, 1992 2. Black WC, Welch HG: Advances in diagnostic imaging and overestimations of disease prevalence and the benefits of therapy. N Engl J Med 328:1237, 1993 3. Boden SD, David DO, Dina TA, et al: Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects: A prospective investigation. J Bone Joint Surg 72A:403, 1990 4. Carette S, Marcoux S, Truchon R, et al: A controlled trial of corticosteroid injections into facet joints for chronic low back pain. N Engl J Med 325:1002, 1991 5. Cherkin DC, Deyo RA, Loeser JD, et al: An international comparison of back surgery rates. Spine 19:1201, 1994 6. Cherkin DC, Deyo RA, Wheeler K, et al: Physician variation in diagnostic testing for low back pain. Who you see is what you get. Arthritis Rheum 37:15, 1994 7. Coxhead CE, Inskip H, Meade TW, et al: Multicentre trial of physiotherapy in the management of sciatic symptoms. Lancet 1:1065, 1981 8. Deyo RA: Magnetic resonance imaging of the lumbar spine: Terrific test or tar baby? N Engl J Med 331:115, 1994 9. Deyo RA: Non-operative treatment of low back disorders: Differentiating useful from useless therapy. In Frymoyer JW (ed): The Adult Spine: Principles and Practice. New York, Raven Press, 1991, p 1567 10. Deyo RA: Nonsurgical care of low back pain. Neurosurg Clin North Am 2:851, 1991 11. Deyo RA: Lumbar spine films in primary care: Current use and the effects of selective ordering criteria. J Gen Intern Med 1:20, 1986 12. Deyo RA, Cherkin D, Conrad D, et al: Cost, controversy, crisis: Low back pain and the health of the public. Ann Rev Publ Health 12:141, 1990 13. Deyo RA, Cherkin D, Loeser JD, et al: Morbidity and mortality in association with operations on the lumbar spine: The influence of age, diagnosis and procedure. J Bone Joint Surg 74A:536, 1992 14. Deyo RA, Diehl AK: Cancer as a cause of back pain: Frequency, clinical presentations, and diagnostic strategies. J Gen Intern Med 3:230, 1988 15. Deyo RA, Diehl AK, Rosenthal M: How many days of bed rest for acute low back pain? A randomized clinical trial. N Engl J Med 315:1064, 1986 16. Deyo RA, Loeser JD, Bigos SJ: Herniated lumbar intervertebral disk. Ann Intern Med 112:598, 1990 17. Deyo RA, Rainville I, Kent DL: What can the history and physical examination tell us about low back pain? JAMA 268:760, 1992 18. Deyo RA, Walsh N, Martin D, et al: A controlled trial of transcutaneous electronic nerve stimulation (TENS) and exercise for chronic low back pain. N Engl J Med 322:1627, 1990 19. Enzmann DR: On low back pain. Am J Neuroradiol 15:109, 1994 20. Ernst E: Smoking, a cause of back trouble? Br J Rheumatol 32:239, 1993 21. Escalante A: Ankylosing spondylitis. A common cause of low back pain. Postgrad Med 94:153, 1993 22. Finneson BE: Low Back Pain, ed 2. Philadelphia, JB Lippincott, 1980 23. Frymoyer JW: Predicting disability from low back pain. Clin Orthop ReI Res 279:101, 1992 24. Frymoyer JW: Back pain and sciatica. N Engl J Med 318:291, 1988 25. Frymoyer JW, Cats-Baril WL: An overview of the incidences and costs of low back pain. Orthop Clin North Am 22:263, 1991 26. Gilbert JR, Taylor DW, Hildebrand A, et al: Clinical trial of common treatments for low back pain in family practice. BMJ 66:100, 1985

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