Low Back Pain: Introduction
Back pain ranks second only to upper respiratory illness as a symptomatic reason for office visits to physicians.1 Approximately 70% of adults have low back pain at some time, but only 14% have an episode that lasts more than 2 weeks. About 1.5% have such episodes with features of sciatica.2, 3 Most causes of back pain respond to symptomatic and physical measures, but some are surgically remediable and some are systemic diseases (cancer or disseminated infection) requiring specific therapy, so careful diagnostic evaluation is important. Features of the clinical history and physical examination influence not only therapeutic choices but also decisions about diagnostic imaging, laboratory testing, and specialist referral.
Anatomic/Physiologic Origins of Findings in the Low Back
Low back pain may arise from several structures in the lumbar spine, including the ligaments that interconnect vertebrae, outer fibers of the annulus fibrosus, facet joints, vertebral periosteum, paravertebral musculature and fascia, blood vessels, and spinal nerve roots. The causes of low back pain generated through these structures include (1) musculoligamentous injuries; (2) degenerative changes in the intervertebral disks and facet joints; (3) herniation of the nucleus pulposus of an intervertebral disk, with irritation of adjacent nerve roots; (4) spinal stenosis (narrowing of the central spinal canal or the lateral recesses of the canal in which the nerve roots travel caudally; this usually results from hypertrophic degenerative changes in the disks, ligamentum flavum, and facet joints); (5) anatomic anomalies of the spine, such as scoliosis and spondylolisthesis, which are often asymptomatic but may cause pain when they are severe; (6) underlying systemic diseases, such as primary or metastatic cancer, spinal infections, and ankylosing spondylitis; and (7) visceral diseases unrelated to the spine, including diseases of the pelvic organs, kidneys, gastrointestinal tract, and aorta (diagnosis of which will not be discussed in the present report).
Prevalence of Diseases That Produce Low Back Pain
Up to 85% of patients cannot be given a definitive diagnosis because of weak associations among symptoms, pathologic changes, and imaging results.4, 5 We assume that many of these cases are related to musculoligamentous injury or degenerative changes.
Anatomic evidence of a herniated disk is found in 20% to 30% of imaging tests (myelography, computed tomography [CT], and magnetic resonance imaging [MRI]) among normal persons.6, 7 These herniations are asymptomatic and result in no clinical disease. The proportion of all persons with low back pain who undergo surgery for a disk herniation is only about 2%.2
In primary care, about 4% of patients with back pain will prove to have compression fractures, 3% have spondylolisthesis, and only 0.7% have spinal malignant neoplasms (primary or metastatic).8-13 Even fewer have ankylosing spondylitis (about 0.3%) or spinal infections (0.01%).8, 14, 15 Widespread recognition of spinal stenosis has occurred only in the last 15 years. It is most common in older adults, but its prevalence is unknown.
Because a specific cause frequently cannot be identified, diagnostic efforts are often disappointing. Instead of seeking a precise cause in every case of back pain, it may be most useful to answer 3 basic questions9: (1) Is there a serious systemic disease causing the pain? (2) Is there neurologic compromise that might require surgical evaluation? (3) Is there social or psychological distress that may amplify or prolong pain? These questions can generally be answered according to medical history and physical examination alone, and a minority of patients requires further diagnostic testing.
Is There Evidence of Systemic Disease?
Malignant neoplasm (primary or metastatic) is the most common systemic disease affecting the spine, although it accounts for less than 1% of episodes of low back pain. Approximately 80% of patients with this diagnosis are older than 50 years (Table 7-1). A history of cancer has such high specificity (0.98) that such patients should be considered to have cancer until proven otherwise. However, only one-third of patients with an underlying malignant neoplasm causing their back pain have a prior cancer diagnosis (sensitivity, 0.31). Unexplained weight loss, pain duration greater than 1 month, and failure to improve with conservative therapy are moderately specific findings. Most patients with back pain caused by cancer report that pain is unrelieved by bed rest (sensitivity > 0.90), but the finding is nonspecific.10 In a study of nearly 2000 patients with back pain, no cancer was identified in any patient younger than 50 years and without a history of cancer, unexplained weight loss, or a failure of conservative therapy (combined sensitivity, 100%).10
Table 7-1Estimated Accuracy of the Medical History in the Diagnosis of Spine Diseases Causing Low Back Pain |Favorite Table|Download (.pdf) Table 7-1 Estimated Accuracy of the Medical History in the Diagnosis of Spine Diseases Causing Low Back Pain
|Diseases to Be Detected ||Source, Year ||Medical History ||Sensitivity ||Specificity |
|Cancer ||Deyo and Diehl,10 1988 ||Age ≥ 50 y ||0.77 ||0.71 |
|History of cancer ||0.31 ||0.98 |
|Unexplained weight loss ||0.15 ||0.94 |
|Failure to improve with a month of therapy ||0.31 ||0.90 |
|No relief with bed rest ||>0.90 ||0.46 |
|Duration of pain > 1 mo ||0.50 ||0.81 |
|Age ≥ 50 y or history of cancer or unexplained weight loss or failure of conservative therapy ||1.0 ||0.60 |
|Spinal osteomyelitis ||Waldvogel and Vasey,16 1980 ||Intravenous drug abuse, urinary tract infection, or skin infection ||0.40 ||NA |
|Compression fracture ||Unpublished dataa ||Age ≥ 50 y ||0.84 ||0.61 |
|Age ≥ 70 y ||0.22 ||0.96 |
|Trauma ||0.30 ||0.85 |
|Corticosteroid use ||0.06 ||0.995 |
|Herniated disk ||Deyo and Tsui-Wu,2 1987; Spangfort,17 1972 ||Sciatica ||0.95 ||0.88 |
|Spinal stenosis ||Turner et al,18 1992 ||Pseudoclaudication ||0.60 ||NA |
|Age ≥ 50 y ||0.90b ||0.70 |
|Ankylosing spondylitis ||Gran,19 1985 ||4 of 5 positive responsesc ||0.23 ||0.82 |
|Age at onset ≤ 40 y ||1.0 ||0.07 |
|Pain not relieved supine ||0.80 ||0.49 |
|Morning back stiffness ||0.64 ||0.59 |
|Pain duration ≥ 3 mo ||0.71 ||0.54 |
The physical examination is less useful than the medical history for detecting underlying cancer,10 except in late stages. Because the breast, lung, and prostate are the most common sources of spinal metastases, these organs should be examined when cancer is suspected.
Spinal infections usually are blood-borne from other sites, including urinary tract infections, indwelling urinary catheters, skin infections, and injection sites for illicit intravenous drugs. One of these sites is identified in approximately 40% of patients with spinal infections (sensitivity, 0.40).16
In patients with spinal infections, the sensitivity of fever is disappointing, varying from 0.27 for tuberculous osteomyelitis to 0.50 for pyogenic osteomyelitis20 and 0.83 for spinal epidural abscess.21 Because 2% of patients in primary care with mechanical low back pain have fever (perhaps because of viral syndromes), specificity for bacterial infection is approximately 0.98.10 Spine tenderness in response to percussion has a sensitivity of 0.86 for bacterial infection, but specificity is poor (0.60).10, 22, 23
Although spinal compression fractures are not systemic diseases, they often occur in persons with generalized osteoporosis. Most patients with this problem do not have a history of identifiable trauma (sensitivity, 0.30). A person with back pain who is receiving long-term corticosteroid therapy is considered to have a compression fracture until proven otherwise (specificity, 0.99). Black and Hispanic women have only one-fourth as many compression fractures as white women.24 As shown in Table 7-1, age greater than 70 years is a relatively specific finding (specificity, 0.96).
Ankylosing Spondylitis and Spine Range-of-Motion Measures
Ankylosing spondylitis shares several historical features with other inflammatory arthropathies, such as rheumatoid arthritis. Calin et al25 described 5 screening questions for ankylosing spondylitis: (1) Is there morning stiffness? (2) Is there improvement in discomfort with exercise? (3) Was the onset of back pain before age 40 years? (4) Did the problem begin slowly? (5) Has the pain persisted for at least 3 months?
With at least 4 positive answers to define a positive “test” result, the sensitivity of these questions was 0.95 and specificity was 0.85,25 although other authors report lower sensitivity.19, 26 When screening for a rare disease such as ankylosing spondylitis, typically, the predictive value of a positive test is low. In an industrial screening program, only 16 of 367 persons with positive criteria proved to have ankylosing spondylitis (a predictive value of 0.04).27 “Inflammatory” symptoms (morning stiffness, night pain, and relief with exercise) are moderately sensitive but nonspecific. All patients with ankylosing spondylitis in 1 population survey reported symptom onset before age 40 years, making this history highly sensitive but nonspecific (Table 7-1).19
Reduced spinal mobility results from fusion of adjacent vertebrae in this condition. The Schober test, which measures distraction between 2 marks on the skin during forward flexion, is a commonly described method for quantifying reduced flexion. Although it is moderately reproducible,23, 28 reduced spine flexion is not specific for inflammatory spondylopathies, being equally common in patients with chronic back pain or spine tumors.29 Reduced chest expansion (using a strict criterion for abnormality, such as expansion ≤ 2.5 cm) is highly specific (0.99) but insensitive in early ankylosing spondylitis (0.09),19, 30 so that predictive values are poor.
Tests for sacroiliac joint tenderness (to discriminate ankylosing spondylitis from mechanical spine conditions) include a hip extension test, anteroposterior pelvic pressure, lateral pelvic compression, and direct pressure on the sacroiliac joints. Unfortunately, these tests are poorly reproducible23, 31 and inaccurate in distinguishing ankylosing spondylitis from mechanical spine complaints.32, 33 Early ankylosing spondylitis is most often suspected from radiographs obtained because of persistent pain.
Although spine flexion is of limited diagnostic value, it may be useful in planning or monitoring physical therapy in patients with low back pain of any cause.34 Range of motion in multiple directions can be assessed with 2 inclinometers (used in the construction industry) with good precision.28, 34 The technique is detailed elsewhere.34
Is There Evidence of Neurologic Compromise?
The spinal cord, cauda equina, and nerve roots are vulnerable to several disorders that cause back pain and sciatica. The most common of these is a herniated intervertebral disk, but other causes include nerve root entrapment in the root canals by bony and ligamentous hypertrophy, spinal stenosis, spinal or paraspinal infections, and neoplasms. Irritation of neurologic structures is manifested as motor, reflex, or sensory dysfunction in the lower extremities and (rarely) as bowel or bladder dysfunction.
The first clue to nerve root irritation is usually sciatica, a sharp or burning pain radiating down the posterior or lateral aspect of the leg (usually to the foot or ankle), often associated with numbness or paresthesia. The pain is sometimes aggravated by coughing, sneezing, or the Valsalva maneuver. Among patients with low back pain alone (no sciatica or neurologic symptoms), the prevalence of neurologic impairments is so low that extensive neurologic evaluation is usually unnecessary.
Sciatica has such a high sensitivity (0.95) that its absence makes a clinically important lumbar disk herniation unlikely.17, 35 Using the accuracy of sciatica in Table 7-1 and a prevalence of surgically important disk herniations of 2%, we estimate the likelihood of disk herniation in a patient without sciatica to be 1 in 1000. Most patients have a long history of recurrent back pain before the onset of sciatica, but when a frank disk herniation occurs, leg pain usually overshadows the back pain. The peak incidence of herniated lumbar disks is in adults between the ages of 30 and 55 years.17
A symptomatic disk herniation tethers the affected nerve root, so pain results from stretching the nerve by straight-leg raising (SLR) from the supine position. This is performed by cupping the heel in 1 hand and keeping the knee fully extended with the other. The straight leg is slowly raised from the examining table until pain occurs. Tension is transmitted to the nerve roots once the leg is raised beyond 30 degrees, but after 70 degrees, further movement of the nerve is negligible.36 A typical positive SLR sign is one that reproduces the patient's sciatica between 30 degrees and 60 degrees of leg elevation.17, 37, 38
A related test is the crossed SLR (CSLR) sign. This occurs when SLR is performed on the patient's well leg and is found to elicit pain in the leg with sciatica. The precision of tests for SLR is shown in Table 7-2.23, 39-41 Visual estimation is reasonably accurate, but a goniometer or inclinometer improves interobserver agreement.
Table 7-2Reproducibility of Physical Examination Findings |Favorite Table|Download (.pdf) Table 7-2 Reproducibility of Physical Examination Findings
|Category ||Test ||Unit of Measurement ||Interobserver Agreement (Statistic) ||Source, Year |
|Tenderness ||Bone tenderness ||Yes/No ||0.40 (κ) ||McCombe et al,23 1989 |
|Soft-tissue tenderness ||Yes/No ||0.24 (κ) ||McCombe et al,23 1989 |
|Muscle spasm ||Yes/No ||“Discarded; too unreliable” ||Waddell et al,39 1982 |
|SLR ||Ipsilateral SLR, inclinometer ||Degrees ||0.78-0.97 (r) ||Hoehler and Tobis,40 1982 Hsieh et al,41 1983 |
|Ipsilateral SLR goniometer ||Degrees ||0.69 (r) ||McCombe et al,23 1989 |
|SLR causes leg pain ||Yes/No ||0.66 (κ) ||McCombe et al,23 1989 |
|Ipsilateral SLR < 75° by visual estimation ||Yes/No ||0.56 (κ) ||Waddell et al,39 1982 |
|CSLR, causes pain ||Yes/No ||0.74 (κ) ||McCombe et al,23 1989 |
|Neurologic examination ||Ankle dorsiflexion weak ||Yes/No ||1.00 (κ) ||McCombe et al,23 1989 |
|Great toe extensors weak ||Yes/No ||0.65 (κ) ||McCombe et al,23 1989 |
|Ankle reflexes normal ||Yes/No ||0.39-0.50 (κ) ||McCombe et al,23 1989 Schwartz et al,42 1990 |
|Any sensory deficit ||Yes/No ||0.68 (κ) ||McCombe et al,23 1989 |
|Calf wasting ||Yes/No ||0.80 (κ) ||McCombe et al,23 1989 |
|Inappropriate signs ||Superficial tenderness ||Yes/No ||0.29 (κ) ||McCombe et al,23 1989 |
|Simulated rotation or axial loading causes pain ||Yes/No ||0.25 (κ) ||McCombe et al,23 1989 |
|SLR with distraction causes pain ||Yes/No ||0.40 (κ) ||McCombe et al,23 1989 |
|Inexplicable pattern, neurologic examination ||Yes/No ||0.03 (κ) ||McCombe et al,23 1989 |
|Overreaction ||Yes/No ||0.29 (κ) ||McCombe et al,23 1989 |
Pain on ipsilateral SLR at 60 degrees is moderately sensitive for herniated lumbar disks but nonspecific, because limitation is often observed in the absence of disk herniations (Table 7-3).43-45 CSLR is less sensitive but highly specific.17, 44, 45, 48 Thus, a positive CSLR test result substantially increases the likelihood of a disk herniation, whereas a negative result is of limited value. The lower the angle of a positive SLR test, the more specific the test becomes and the larger the disk protrusion found at surgery.46, 49
Table 7-3Estimated Accuracy of Physical Examination for Lumbar Disk Herniation Among Patients With Sciatica |Favorite Table|Download (.pdf) Table 7-3 Estimated Accuracy of Physical Examination for Lumbar Disk Herniation Among Patients With Sciatica
|Test ||Source, Year ||Sensitivitya ||Specificitya ||Comments |
|Ipsilateral SLR ||Kosteljanetz et al,43 1984; Hakelius and Hindmarsh,44 1972 ||0.80 ||0.40 ||Positive test result; leg pain at < 60° |
|CSLR ||Spangfort,17 1972; Hakelius and Hindmarsh,44, 45 1972 ||0.25 ||0.90 ||Positive test result: reproduction of contralateral pain |
|Ankle dorsiflexion weakness ||Spangfort,17 1972; Hakelius and Hindmarsh,44 1972 ||0.35 ||0.70 ||HNP usually at L4-5 (80%) |
|Great toe extensor weakness ||Hakelius and Hindmarsh,44 1972; Kortelainen et al,46 1985 ||0.50 ||0.70 ||HNP usually at L5-S1 (60%) or L4-5 (30%) |
|Impaired ankle reflex ||Spangfort,17 1972; Hakelius and Hindmarsh,44 1972 ||0.50 ||0.60 ||HNP usually at L5-S1; absent reflex increases specificity |
|Sensory loss ||Kosteljanetz et al,43 1984; Kortelainen et al,46 1985 ||0.50 ||0.50 ||Area of loss poor predictor of HNP level |
|Patella reflex ||Aronson and Dunsmore,47 1963 ||0.50 ||NA ||For upper lumbar HNP only |
|Ankle plantar flexion weakness ||Hakelius and Hindmarsh,44 1972 ||0.06 ||0.95 || |
|Quadriceps weakness ||Hakelius and Hindmarsh,44 1972 ||<0.01 ||0.99 || |
Straight-leg raising is most appropriate for testing the lower lumbar nerve roots (L5 and S1), where the majority of herniated disks occur. Irritation of higher lumbar roots is tested with the femoral nerve stretch test (flexing the knee with patient prone), but the precision and accuracy of this test are unknown.
Assessment of Motor, Reflex, and Sensory Function
Ninety-eight percent of clinically important lumbar disk herniations occur at either the L4 to L5 or the L5 to S1 intervertebral level,17, 44-46 causing neurologic impairments in the motor and sensory territories of the L5 and S1 nerve roots. Thus, the most common neurologic impairments are weakness of the ankle and great-toe dorsiflexors (L5), diminished ankle reflexes (S1), and sensory loss in the feet (L5 and S1).17, 44-46 In a patient with sciatica, the neurologic examination can focus on these functions.
Ankle dorsiflexor strength is tested by having the supine patient dorsiflex the ankle against the examiner's resistance. Inability to maintain dorsiflexion against the examiner should be considered weakness, and the healthy side should be checked for comparison. This method shows excellent precision (Table 7-2) and is more reproducible than the patient's ability to heel stand.23 Ankle dorsiflexor weakness rarely occurs in isolation and is nearly always associated with weak toe dorsiflexion, sensory deficits, or impaired reflexes.50 For toe strength, the supine patient is instructed to maximally dorsiflex the great toe (“point your big toe at your nose” seems to work well) and resist the examiner's effort to flex the toe with 2 fingers.
Ankle reflexes are more difficult to reproduce, and patient positioning may be important. The side-lying, prone, and kneeling positions are probably best (rather than the sitting position), but we are unaware of comparative data. The foot is gently rocked until relaxation is obtained, and the calf muscles should be held under slight tension by dorsiflexing the foot. Estimated κ values for the precision of ankle reflexes range from 0.39 to 0.50.23, 48 Schwartz et al42 found that a plantar tap is as good as an Achilles tendon tap (estimated κ = 0.55). In this technique, the patient lies supine and the ball of the foot is tapped with the reflex hammer. The plantar tap was preferred by patients and could be elicited in 91% of patients younger than 65 years but in only 71% of patients older than 65 years.
Ankle plantar flexion is an S1 function, but only severe impairments can be clinically detected, and sensitivity for disk herniation is low (Table 7-3). Toe walking appears to be an unreliable method of assessing plantar flexion strength (κ = 0).23 Hamstring and hip extensor strength have been used to evaluate S1 root injuries, but their precision and accuracy are unknown. Muscle wasting indicates longstanding denervation or disease and may be detected visually. Good precision was noted for observations of anterior compartment and hamstring wasting in one study (Table 7-2).23
Sensory examination of the lower extremities takes time. Patients distinguish differences in pain intensity by pinprick more accurately than differences in touch or temperature, and sensory impairment from nerve root compression is most frequent in the distal extremes of the dermatomes.51 Therefore, an efficient strategy is to check for symmetry of pain elicited by pinprick in the extremes of the L4, L5, and S1 dermatomes (the medial aspect, dorsum, and lateral aspect of the feet) (Figure 7-1).
Higher lumbar nerve roots account for only about 2% of lumbar disk herniations. They are suspected when numbness or pain involves the anterior thigh more prominently than the calf (Figure 7-1). Testing includes knee reflexes, quadriceps strength, and psoas strength.17, 47, 50 Quadriceps weakness is virtually always associated with impairment in the patella reflex.50
The accuracy of neurologic findings for the diagnosis of a herniated disk is only moderate (Table 7-3). Considering combinations is helpful, however, because a finding of impaired ankle reflexes or weak foot dorsiflexion would have a sensitivity of almost 90% for patients with surgically proven disk herniations.17 Multiple findings related to SLR or neurologic examination increase the probability that a herniated disk will be found at surgery.52
The mean age of patients at surgery for spinal stenosis is 55 years, with an average symptom duration of 4 years.18 The characteristic history is that of neurogenic claudication: pain in the legs and occasionally neurologic deficits that occur after walking. In contrast to arterial ischemic claudication, neurogenic claudication is more likely to occur on standing alone (without ambulation), may increase with cough or sneeze, and is associated with normal arterial pulses.53 The sensitivity of neurogenic claudication is modest (about 0.60),18 but it is probably quite specific.
Few data are available concerning the accuracy of physical examination because stenosis has been widely recognized only in recent years. Diagnostic criteria, indications for surgery, and the natural history are still being elucidated. Increased pain on spine extension is typical of stenosis (whereas flexion is usually most painful with herniated disks), but accuracy data are unavailable. The sensitivity of leg pain is about 85%; neurologic abnormalities, about 60%; and abnormal SLR, about 50%.18, 53
A massive midline disk herniation may cause spinal cord or cauda equina compression, requiring immediate surgical referral. Fortunately, the cauda equina syndrome occurs in only 1% to 2% of all patients with lumbar disk herniations who come to surgery,17 so its prevalence among all patients with low back pain is about 0.0004. The most consistent finding is urinary retention, with a sensitivity of 0.90.54-56 The most common sensory deficit occurs over the buttocks, posterior-superior thighs, and perineal regions (“saddle anesthesia”), with a sensitivity of about 0.75.54-56 Anal sphincter tone is diminished in 60% to 80% of cases.54-56 Assuming a specificity of about 95%, the predictive value of a negative test result (no urinary retention) would be almost 100%. Unilateral or bilateral sciatica, sensory and motor deficits, and abnormal SLR results are all common, with sensitivities of greater than 0.80.54-56
Indications for Imaging Tests
There is a growing consensus that radiographs are not necessary for every patient with low back pain because of a low yield of useful findings, potentially misleading results, substantial gonadal irradiation, and common interpretive disagreements. The Quebec Task Force on Spinal Disorders suggested that early radiography was necessary only in the face of neurologic deficits, age older than 50 years or younger than 20 years, fever, trauma, or signs of neoplasm.57 Table 7-1 indicates screening questions that can exclude neoplasm according to patient medical history alone.10
MRI and CT can be used even more selectively, usually for surgical planning. The finding of herniated disks and spinal stenosis in many asymptomatic persons6, 7 indicates that imaging results alone can be misleading, and valid decision making requires correlation with the medical history and physical examination.58
Is There Evidence of Social or Psychological Distress That May Amplify or Prolong Pain?
Some features of patient medical history influence management regardless of the exact spinal pathology. Chronic pain or depression may be indications for the use of antidepressant medication rather than opiates. Alcohol or drug abuse influences the choice of medications and requires specific intervention. Disability compensation claims or litigation may affect initial evaluation and prognosis, and patients seeking compensation often respond poorly to a variety of treatments.59
Patients with chronic low back pain (≥ 3 months) present complex problems, and often, a pathoanatomic cause is not apparent.60 Unlike acute pain, chronic pain is often not associated with ongoing tissue injury, serves no biological usefulness, and is not accompanied by the autonomic response of sympathetic overactivity. Vegetative signs, such as sleep disturbance, appetite disturbance, and irritability, appear, and pain is often reinforced or perpetuated by social and psychological factors. Back pain can affect employment, income, family, and social roles, producing psychological distress.60, 61 Resulting somatic amplification can serve the patient's needs for economic survival and maintenance of self-esteem.61
In patients with chronic low back pain, the absence of systemic disease and treatable anatomic abnormalities should be confirmed by medical history, physical examination, and review of diagnostic tests. Neurologic abnormalities often prove to be longstanding and may persist after surgical interventions. Evidence of psychological distress should be sought because this may respond to direct intervention and improve the likelihood of response to other treatments. The Minnesota Multiphasic Personality Inventory is impractical in most primary care settings, and shorter depression scales are useful for screening.62, 63
Waddell et al64 proposed 5 categories of inappropriate or nonorganic signs that correlated with other indicators of psychological distress: (1) inappropriate tenderness that is superficial or widespread; (2) pain on simulated axial loading by pressing on the top of the head, or simulated spine rotation (performed by holding the patient's arms to the side while rotating the hips, ensuring that the shoulders and hips rotate together); (3) “distraction” signs, such as inconsistent performance between SLR in the seated position vs the supine position; (4) regional disturbances in strength and sensation that do not correspond with nerve root innervation patterns; and (5) overreaction during the physical examination. The occurrence of any 1 sign was of limited value, but positive findings in 3 of the 5 categories suggested psychological distress. The precision of nonorganic signs was reported by Waddell et al64 to be high, but subsequent evaluation found poor precision in the regional disturbance category (Table 7-2).23
Summary and Recommendations
A few key questions can raise or lower the probability of underlying systemic disease. The most useful items are age, history of cancer, unexplained weight loss, duration of pain, and responsiveness to previous therapy.
Intravenous drug use or urinary infection raises the suspicion of spinal infection.
Ankylosing spondylitis is suggested by the patient's age and sex (most common in young men), but most clinical findings have limited accuracy.
Failure of bed rest to relieve the pain is a sensitive finding for all these systemic conditions, although not specific.
Neurologic involvement is suggested by symptoms of sciatica or pseudoclaudication. Pain radiating distally (below the knee) is more likely to represent a true radiculopathy than pain radiating only to the posterior thigh. A history of numbness or weakness in the legs further increases the likelihood of neurologic involvement.
Inquiry should be made concerning symptoms of the cauda equina syndrome: bladder dysfunction (especially urinary retention) and saddle anesthesia in addition to sciatica and weakness.
The psychosocial history helps to estimate prognosis and plan therapy. The most useful items are a history of failed treatments, substance abuse, and disability compensation. Brief screening questionnaires for depression may suggest important therapeutic opportunities.
Fever suggests the possibility of spinal infection. Vertebral tenderness is a sensitive finding for infection but not specific.
The search for soft-tissue tenderness is unlikely to provide reproducible data or demonstrably valid pathophysiologic inferences.23, 39
Limited lumbar flexion is not highly sensitive or specific for ankylosing spondylitis or other diagnoses. However, limited spinal motion may be useful in planning physical therapy and monitoring response.
In a patient with sciatica or possible neurogenic claudication, SLR should be assessed bilaterally, preferably with an inclinometer or goniometer.
Neurologic examination emphasizes ankle dorsiflexion strength, great-toe dorsiflexion strength, ankle reflexes, and the sensory examination. A rapid screening sensory examination would test pinprick sensation in the medial, dorsal, and lateral aspects of the foot.
For the patient with chronic pain, all the evaluations described herein should be completed. Anatomically “inappropriate” signs may be helpful in identifying psychological distress as a result of or as an amplifier of low back symptoms. The most reproducible of these signs are superficial tenderness, distracted SLR, and the observation of patient overreaction during the physical examination.
Author Affiliations at the Time of the Original Publication
From the Health Services Research and Development Field Program, (Washington) Veterans Affairs Medical Center (Drs Deyo and Kent) Seattle; the Departments of Medicine (Drs Deyo and Kent) and Health Services (Dr Deyo), University of Washington, Seattle; and the Department of Rehabilitation Medicine, Tufts University School of Medicine, Boston, Massachusetts (Dr Rainville).
This report was supported in part by the Northwest Health Services Research and Development Field Program, Seattle Veterans Affairs Medical Center; by grant HS-06344 from the Agency for Health Care Policy and Research (the Back Pain Outcome Assessment Team); and by grant 88298-2H from the John A. Hartford Foundation through the Multi-Institutional Technology Assessment Consortium.
Darlena Bursell assisted in the preparation of the manuscript, and Monica Hayes helped to coordinate study activities.
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