Authors: David Della-Giustina, MD, FACEP, Lieutenant Colonel, United States Army, Adjunct Assistant Professor of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, Clinical Assistant Professor of Medicine, University of Washington School of Medicine, Emergency Medicine Consultant to the Surgeon General of the Army, Chairman, Department of Emergency Medicine, Madigan Army Medical Center, Fort Lewis, WA; and Robert Nolan, DO, DC, Captain, United States Army, Resident, Madigan-University of Washington Affiliated Emergency Medicine Residency, Madigan Army Medical Center, Fort Lewis, WA.
Peer Reviewer: Louis Kuritzky, MD, Clinical Assistant Professor, Department of Community Health, University of Florida, Gainesville.
Disclaimer: The opinions and assertions contained herein are the private views of the authors and should not be construed as official or as reflecting the views of the Department of Army or the Department of Defense.
Introduction
Low back pain is among the top three most common complaints seen in primary care ambulatory medicine. Affecting up to 90% of the population at some time in their lives, it is second only to upper respiratory tract infection as a symptom-related reason for primary care visits.1-3 Men and women are equally afflicted with low back pain, with a steadily increasing prevalence with age.2-4
Economically, low back pain has a major impact on the work force in the United States. It is the most common and most expensive cause of work-related disability in people younger than 45 years. It is the second most common cause of temporary disability and work absenteeism for all ages. At any one time, an estimated 1% of U.S. adults are temporarily disabled with approximately 400,000 compensable back injuries per year.4,5 In 1990, the direct and indirect costs (including lost earnings) of diagnosing and treating low back pain totaled more than $58 billion.1-3
Fortunately, 80-90% of patients with acute low back pain will resolve their symptoms within 4-6 weeks with no clear cause of their symptoms.4,6 Although this majority will improve with conservative management, it is important to evaluate all patients with back pain properly to rule out significant neurologic or life-threatening diseases that can be devastating in some who present with early symptoms. This evaluation easily is performed in the office by focusing the history and physical examination on the identification of the red flags of back pain. (See Table 1.) These red flags are important historical and physical features that are markers of serious conditions that require close attention and potentially diagnostic testing. These red flags were defined in a 1994 set of guidelines on acute low back pain published by the Agency for Health Care Policy and Research.7
The History
In reality, a history focusing on the red-flags is the most critical screening tool for identifying serious disease. Directing the history with a focus on the red flags allows for an efficient, cost-effective evaluation.
Duration of Symptoms. Low back pain is differentiated into three categories based on duration of the symptoms. Pain lasting fewer than six weeks is defined as acute. Pain lasting between six and 12 weeks is subacute. Any pain that has been ongoing for more than 12 weeks is termed chronic.8 Pain lasting longer than six weeks is the first red flag as 80-90% of all episodes of low back pain will resolve within six weeks.9 A longer history of pain raises the suspicion of a more serious cause for the symptoms and thus requires further evaluation as described later.
If the patient has been assessed for low back pain previously and has ongoing pain for more than six weeks, he or she should be evaluated further. However, if the patient has had pain for 4-6 weeks but has not been treated appropriately, it is reasonable to delay the work-up and to follow him or her closely to ensure improvement. This delay in evaluation assumes that the patient has no other red flags and that the symptoms are minor or improving. In these cases, close follow-up is a reasonable approach.
In the patient who has chronic symptoms but has already undergone a complete evaluation, the physician should review the thoroughness of the work-up to ensure it has been complete and that vital clues or signs have not been missed. If the imaging study and lab results can be reviewed to ensure that they were indeed “normal,” then it is reassuring that proceeding with additional evaluation is not necessary.
Age of the Patient. Patients with onset of back pain prior to age 18 years or after 50 years raise a red flag based on the fact that they have a higher likelihood of a serious cause for their symptoms. In both of these age groups, tumor and infection are more prevalent. Further, patients younger than 18 years who present with back pain have a higher incidence of congenital and bony abnormalities, such as spondylolisthesis or spondylolysis. In those older than 50 years, non-mechanical causes, such as a rupturing abdominal aortic aneurysm and other intra-abdominal processes, are more common.
Location and Radiation of the Pain. Pain that originates from muscular or ligamentous strain, or disc disease without nerve involvement, is located primarily in the back, possibly with referral into the buttocks or thighs. This is common and not concerning. However, radicular pain below the knee, termed sciatica, is a red flag for nerve root compression, such as is seen with a herniated disc, or inflammation below the L3 nerve root. This is based on the dermatomal distribution of the nerve roots and the fact that proximal compression or inflammation of the nerve root potentially will affect the mechanoreceptors and sensory fibers traversing the entire nerve.5 This is important because 95% of herniated discs involve either the L4-L5 or the L5-S1 lumbar discs. These disc herniations will impinge on the L5 or S1 nerve roots respectively, thereby producing a radiculopathy that extends into the lower leg and foot along the dermatomal distribution for that nerve.8,10 Sciatica may be associated with low back pain, but patients with sciatica usually complain more of the leg symptoms rather than back pain. The lifetime prevalence of sciatica is approximately 40%. However, only 1-3% of patients with low back pain have associated sciatic symptoms.6,8,10
History of Trauma. Any history of major trauma is a red flag for the possibility of fracture and should prompt the physician to order plain radiographs of the involved spine. Be more concerned with minor trauma in elderly patients, as they may sustain a fracture of the spine with even minimal trauma such as falling from standing or even falling from sitting in a chair. This predominantly is due to the osteoporosis that occurs with aging.
Systemic Complaints. Constitutional symptoms, such as fever, chills, night sweats, malaise, and an undesired weight loss, suggest the possibility of infection or malignancy. These symptoms are even more striking if the patient has additional infectious risk factors, including immunocompromised status, diabetes, injection drug use, or a recent bacterial infection such as pneumonia or urinary tract infection. Also, a recent genitourinary or gastrointestinal procedure may predispose the patient to infection secondary to bacteremia. One maxim regarding back pain in the injection drug user is that the patient has a spinal infection until definitively ruled out with imaging studies.
Atypical Pain Features. The typical description of benign low back pain is that of a dull, aching pain that generally wor-sens with movement but improves with rest and lying still. Red flags for tumor and infection include night pain that awakens the patient from sleep or pain that is unrelenting despite appropriate or even supernormal use of analgesics and rest. Pain that occurs or worsens with coughing, Valsalva’s maneuver, or prolonged sitting, and is relieved by lying supine is consistent with a herniated disc.1,8,10 Spinal stenosis is associated with bilateral sciatic pain that is worsened by activities such as walking, prolonged standing, and back extension and is relieved by rest and forward flexion.
Associated Neurologic Deficits. Most patients with routine low back pain have no associated neurologic deficits. As previously mentioned, only 1-3% of all patients with acute low back pain have associated sciatica. Any severe or rapidly progressive neurologic deficit or complaint raises a red flag for a more serious problem than a routine lumbosacral strain.
Ask every patient presenting with low back pain about bowel and bladder incontinence. If such incontinence is reported, an epidural compression syndrome such as spinal cord compression, cauda equina syndrome, or conus medullaris syndrome must be ruled out. One particular group of patients can cause some consternation in this regard. These are the patients who have a history of urinary incontinence, ranging from one episode to long-term incontinence. These patients should be evaluated by measuring a bladder postvoid residual volume. A large postvoid residual indicates overflow incontinence, which in the setting of low back pain suggests significant neurologic compromise and mandates an immediate evaluation for an epidural compression syndrome. A negative postvoid residual (no residual volume) essentially rules out significant neurologic compromise as the etiology for the incontinence.11 Other neurologic complaints such as paresthesias, numbness, weakness, and gait disturbances, need to be fully addressed by the history and physical examination to determine whether the symptoms involve single or multiple nerve roots and whether they are acute, chronic, stable, or progressive.
Past Medical History. A history of cancer raises is a red flag due to the possibility of spinal metastases. In 96% of cases, back pain is the initial symptom of such metastases. More specifically, patients with a history of cancer of the breast, lung, thyroid, kidney, or prostate and those with a history of myeloma, lymphoma, or sarcoma are at high risk for metastatic disease to the spine.12 The evaluation of these patients is covered later in this article.
Urinary, Abdominal, or Chest Complaints. The most serious of these is a ruptured abdominal aortic aneurysm. The palpation of an enlarged aorta or auscultation of an abdominal bruit should raise concern for possible aortic aneurysm, with ultrasound confirmation as a first step. Other potential causes of pain referred to the back include pancreatitis, a posterior lower lobe pneumonia, nephrolithiasis, and renal infarct.
Physical Examination
The physical examination for the patient who presents with low back pain is focused toward ruling out any red flags and to identifying and localizing specific neurologic deficits.
Vital Signs. Fever, if present, strongly raises the suspicion of infection. Unfortunately, the sensitivity of fever is disappointing, varying from 27% for tuberculous osteomyelitis, to 50% for pyogenic osteomyelitis, and 83% for spinal epidural abscess.11
General Appearance. Patients with a benign etiology of back pain are most comfortable when lying still. Those patients who are writhing in pain or having excessive pain should raise suspicion for spinal infection, nephrolithiasis, and abdominal aortic aneurysm.
Abdomen. Examine the abdomen in all patients with back pain. This examination includes auscultation for bruits and palpation for tenderness, masses, or a pulsatile aorta that may be consistent with an aortic aneurysm.
Back. Examine the back for signs of underlying disease. Erythema, warmth, and purulent drainage suggest infection; swelling raises a red flag for trauma. Palpation and percussion of the vertebral bodies is the next step. Point tenderness to percussion is found with fractures and bacterial infection, with a sensitivity of 86% and specificity of 60% for infection.11
The final portion of the back examination consists of the straight leg raise test. With the patient lying in the supine position, the examiner must lift each leg separately, without any patient assistance, to approximately 70° in an attempt to produce some symptoms. Reproduction of the patient’s sciatic pain or a new radicular pain down the affected leg below the knee is a positive test. This radicular pain is worsened by ankle dorsiflexion and improved with ankle plantar flexion or by decreasing the elevation of the leg. Reproduction of the patient’s back pain or pain in the hamstring area is not a positive result. It is important to clearly understand the results of the test, as a positive straight leg raise test is approximately 80% sensitive for a herniated disc at either the L4-L5 or L5-S1 levels. This is significant as 95% of herniated discs occur at these levels.8,10 Radicular pain in the affected leg when lifting the asymptomatic leg (positive crossed straight leg raise) is highly specific yet insensitive for nerve root compression by a herniated disc.2,8,10
Neurologic Examination. The neurologic examination is the most important portion of the physical examination. It will allow the physician to exclude an impending surgical emergency and to define and localize any neurological deficits. The neurological examination needs to be directed toward testing specific nerve roots. (See Table 2.) Sensation may be tested by using light touch initially, followed by a pinprick, temperature, proprioception, and vibration if there are any concerns regarding diminished sensation. The motor examination is performed by focusing on the muscles innervated by a specific nerve root. (See Table 2.) The patellar and Achilles reflexes should be tested and compared for symmetry.
Rectal Examination. A rectal exam is not mandatory for all patients with back pain. However, it should be performed in all patients with red flags, especially those with neurologic complaints or severe pain. The rectal examination evaluates rectal tone and sensation, and can help rule out prostatic and rectal masses and perirectal abscess.12 The loss of deep sphincter tone indicates an S5 defect. The absence of the superficial reflex or perineal sensation indicates dysfunction of the S2-S4 nerve roots. Poor rectal tone in association with back pain, and saddle anesthesia indicates cauda equina syndrome.
Diagnostic Studies
Laboratory Tests. In evaluating which tests to order, the differential diagnosis must be narrowed to a set of potential etiologies. In those cases in which there is concern about infection, tumor, or a rheumatologic etiology for the patient’s symptoms, order a complete blood cell count, erythrocyte sedimentation rate (ESR), and urinalysis. The white blood cell count may be normal or elevated in patients with infection, whereas the ESR almost universally is elevated.13-15 C-reactive protein is likely to be elevated in those patients with spinal infection; however, there are no studies to support this assumption or its use in screening for spinal infection.
In patients with neoplastic disease involving the spine, these tests generally are normal, except for the ESR, which may be elevated.16 Urinalysis is obtained to rule out urinary tract infection as a source of infection that may have seeded the spine or primary renal disease referred to the back. If the laboratory results are normal but infection or tumor still is suspected, the next step is to order diagnostic imaging of the spine.
Plain Radiographs. Obtain AP and lateral plain radiographs if fracture, tumor, infection, or nerve dysfunction is suspected. Oblique projections rarely are indicated in adults because they add little information while more than doubling gonadal radiation exposure and cost.8 In instances in which the patient has significant symptoms and will undergo definitive imaging with magnetic resonance imaging (MRI), it is reasonable to omit the plain radiographs as they will not add anything to the diagnostic evaluation.
MRI. The definitive imaging modality of choice in most situations involving back pain is MRI. It offers the best resolution for lesions in the vertebral bodies, spinal canal, and spinal cord as well as providing excellent visualization of disc disease. Due to this excellent resolution, emergent MRI is the modality of choice for evaluating for suspected spinal infection and epidural compression syndrome. Further, its routine or urgent use is indicated in evaluating for neoplastic processes of the entire spine and disc disease or when the patient’s symptoms fail to resolve after 6-8 weeks.2,17,18 The average cost of a lumbosacral MRI ranges from $860 to $2000.
Computed Tomography (CT) Scan. CT scanning is superior to MRI in evaluating bony detail of the spine. It is most useful in evaluating vertebral fractures, the facet joints, and the posterior elements of the spine. Its widespread availability makes it useful in emergencies when MRI is either unavailable or unsuitable. CT myelography is the best substitute when one suspects lesions involving the spinal canal and MRI is unavailable or if there is some contraindication to MRI.18,19 The average cost of a lumbosacral CT scan ranges from $500 to $600.
Radionuclide Imaging. This is used primarily to localize infectious or metastatic lesions of the spine. Radionuclide imaging has a high sensitivity but low specificity for these problems. If positive, it commonly requires a follow-up confirmatory test, such as MRI or CT. It also is useful in evaluating for stress fractures in adolescents with low back pain.
Back Pain Treatment
The majority (90%) of patients with low back pain suffer from uncomplicated soft-tissue injury. It should be stressed from the outset that the vast majority of these patients will respond very favorably to conservative management in 4-6 weeks.20 In these patients, there are many treatment options. No one treatment has been demonstrated to be clearly superior, so there is much confusion and debate both within the medical community and the lay population regarding what is the best treatment. Regardless of treatment plan, the patient should be reassured that rapid recovery is expected.
There are several approaches to the initial management of acute low back pain. Pain and mobility usually are the most concerning problems for the patient. Initial pain of acute low back pain should be managed with analgesic medications and activity modification.
Analgesic Medications. Analgesics are a mainstay for treatment of acute low back pain and should be used liberally. For mild to moderate pain acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) may be sufficient to manage the symptoms. For more severe pain, a short course of opiate analgesics, such as hydrocodone or oxycodone, should be used while weighing the potential to induce dependence against the analgesic benefit. It should be indicated at the outset that opioids are intended as rescue medication rather than long-term maintenance medication. If opiates are prescribed, it is prudent to advise the patient about the potential need for laxatives, and to make them available, remembering that straining at defecation could worsen the low back pain symptoms. Which analgesics are the best to use? To date, no analgesic medication has been shown to be significantly better than another in reducing pain from an acute episode. A recommendation is to start with one of the less expensive NSAIDs, such as ibuprofen (Advil, Motrin) or naproxen (Aleve), in conjunction with acetaminophen (Tylenol). If the patient has more severe pain, add one of the opioid analgesics, but warn the patient not to exceed the acetaminophen recommended maximum of 4 g daily if the opiate prescribed already has acetaminophen with it as part of a combination medication, such as acetaminophen plus oxycodone (Percocet). There should be similar warnings for some of the new NSAID-opiate analgesics now on the market. When reviewing the pain management plan with the patient, it is important to emphasize that the patient should take the medication on a regular schedule rather than having the patient take it on demand when the pain worsens. This is most important for the first several days or at least until the pain cycle of more severe pain is broken. In the past, COX-2 inhibitors were suggested as alternative to NSAIDs in patients with concerns for gastrointestinal or renal toxicity. However, in light of recent literature regarding the COX-2 safety profile, they should be used sparingly and only after discussion with the patient of the risk/benefit ratio. The concomitant use of misoprostol (Cytotec) or omeprazole (Prilosec) has been shown to reduce the risk of clinically important gastrointestinal bleeding during NSAID therapy.21
Muscle relaxants, such as diazepam (Valium), methocarbamol (Robaxin), metaxalone (Skelaxin), carisoprodol (Soma), and cyclobenzaprine (Flexeril), have been found to be more effective than placebo in reducing the symptoms of low back pain but have not been found to be better than NSAIDs.22-24 Further, no one relaxant has been proven as more efficacious than the other relaxants. Muscle relaxants commonly cause sedation as a side effect as well an addiction potential for some of the relaxants. Although efficacious, there is no one muscle relaxant that is proven superior to the others. There is conflicting literature on the value of the combination muscle relaxant plus an NSAID.
The addition of cyclobenzaprine to high-dose ibuprofen (800 mg) in the first 48 hours of acute low back pain does not seem to have a benefit over ibuprofen alone.25 However, if the patient demonstrates significant muscle spasm of the paraspinal musculature, muscle relaxants may be useful.22,26 It is important to understand that most muscle relaxants exert benefit only in the first four days of an attack when spinal muscular spasm is at its zenith. Rarely is spasm a component after the first week of the injury. Unless there are unusual circumstances, muscle relaxants should be avoided after 1 week post injury.
Activity Modification, A common concern for both the patient and physician is activity level and the timing of work restrictions. Significant anxiety and cost are associated with these considerations. This issue should begin with a careful review of those activities and behaviors that exacerbate low back pain. The patient should be instructed on proper carrying, lifting, bending, and reaching. In addition, activities that require prolonged bending or sitting as well as sedentary activities should be modified or avoided. In patients in whom uncomplicated back pain is diagnosed, maintenance of activity to tolerance of pain is the goal. Bed rest has no benefit and may ultimately, be harmful in the recovery of the patient.27 Studies have shown that bed rest even for only 2 days is not beneficial in comparison to early mobilization and activity.28 Even in patients with sciatica, bed rest has shown no benefit in comparison to early mobilization.27,29 The patient should be told to sit in a chair that is easy to rise from and to frequently move and walk. Activity should be curtailed to pain level but there is a significant benefit to movement. Short walks, stretching and mobilization has the most favorable outcome. Recent studies indicate that patients who resume their normal activities to the extent tolerable recovered faster than those who stayed in bed for two days.27-29 Moreover, active exercise has not been shown to be beneficial during the acute crisis of back pain, although it may be important, once the patient recovers to prevent future episodes.30 Patients should be advised to resume normal daily activities and curtail activities that exacerbate the pain.
Manipulation. One of the most controversial treatments of acute low back pain is manipulation. Many studies have looked at the efficacy of manipulation in patients with uncomplicated low back pain. Most researchers have found that while manipulation may have some minimal, limited, short-term benefit, the lasting benefit is unproven.31 In one study, manipulation acutely was shown to be no better than physical therapy and only slightly better, in terms of patient satisfaction with care at one and four weeks, than giving the patient a $1 educational booklet.32 Furthermore, a second study demonstrated that manipulation was no better than standard medical therapy in terms of clinical outcome.33 Finally, in a recent Cochrane Review, spinal manipulative therapy was found to be no better than standard treatment for patients with acute or chronic back pain.34 Consequently, the utility and cost-effectiveness of manipulative therapy still is in question and is not recommended routinely for most patients with acute lumbosacral strain. However, if one is going to recommend it to patients, the benefit is greatest when an experienced and conservative chiropractor, osteopath, or therapist provides the treatment.33
Other Physical Modalities. Other treatments common for low back pain include the following: traction, diathermy, coetaneous laser therapy, exercise, ultrasound, homeopathy, acupuncture, massage, and transcutaneous electrical nerve stimulation (TENS). None of these treatments have shown significant improvement in the recovery rate from acute low back pain.7 Heat and ice therapy have the benefit of being very inexpensive and may be marginally effective in reducing the subjective complaints of acute low back pain. Corsets and braces have shown no benefit in the treatment of low back pain35 and only add to the cost of treatment. Physical exercise and strengthening in the acute phase of low back pain should be avoided. Early mobilization is very beneficial but strenuous rehab in the acute phase may be harmful. As the acute pain subsides, moderate stretching and strengthening of both abdominal muscles and back muscles are beneficial.30 This will be discussed in management of chronic pain.
Treatment of Chronic Low Back Pain
As mentioned above, 90% of patients suffering from low back pain will recover in 4-6 weeks. Those who do not improve in this time period are considered to have subacute or chronic low back pain. Multiple studies have shown the benefit of exercise in the management of chronic low back pain.30 Again, as in acute low back pain, activity modification is important. Instruction on proper lifting, carrying, and bending should be reviewed. Evaluation of current activities that may be exacerbating the condition, such as working in a stooped position for hours on end, for example, should be modified. Smoking is correlated with chronic back pain, and cessation should be strongly encouraged. In patients with no radicular symptoms who have uncomplicated chronic back pain, a simple exercise routine can be initiated. Physical therapy focusing on strengthening of abdominal and back muscles in addition to improving general conditioning has proven to be beneficial. Reduction in body weight and improved cardiovascular fitness also are beneficial. Increased flexibility of both the trunk musculature and lower extremity musculature also should be encouraged. To date, there are no good data to support one specific exercise program over another.30
Steroid Injection. There remains significant controversy as to the benefits, if any, to steroid injection into the facet joints or local tissues of the back.36 Some patients may benefit from this treatment. Disk injections do not seem to be beneficial.36 Epidural steroid injection, which generally is performed by a qualified anesthesiologist, may be beneficial to those patients with post surgical scarring or with severe impairment from spinal stenosis. The success of such treatment is debatable and inconclusive. If patients do improve, it usually is short term with a return of symptoms in four to 10 months.37
Behavioral therapy, including biofeedback, has been shown to be beneficial when used in conjunction with a comprehensive rehabilitation approach including physical, mental, and behavioral approaches.38
Medications. Analgesics such as acetaminophen and NSAIDS remain the cornerstone for pain control. Narcotics and muscle relaxants should be avoided in chronic pain as addiction becomes very likely. Antidepressants, especially tricyclic antidepressants (TCAs), have been shown to be beneficial in the treatment of chronic low back pain.39
Other Modalities. Acupuncture has not been shown to be beneficial in the treatment of chronic back pain. One study showed some improvement at 10 weeks but no difference at 1 year to standard therapy.40 TENS units have been shown to be no more effective than placebo in treatment of chronic low back pain.41 Massage has some benefit for patients with chronic low back pain when combined with exercise.42
Low Back Pain with Sciatica
Sciatica is only a symptom in 1-3% of individuals with low back pain, whereas it is found in 95% of those with disc herniation.6,8 The outcome for patients with a herniated disk generally is positive, with 50% recovering in six weeks, and only 5-10% ultimately requiring surgery.2,8 Interestingly, two separate studies demonstrated that the beneficial results of surgery only appear in the first two years after the procedure with there being no difference in the patients’ symptoms at four and 10 years post-operatively.2,8 The management of patients with back pain with sciatica is similar to the management of the patient with uncomplicated acute low back pain: Activity as tolerated, limited to no bed rest, and analgesics, all as previously described. Manipulation is best avoided in these patients due to the risk of worsening the neurological deficit or symptoms. One difference is in the use of steroids. While there is no role for systemic steroids, epidural steroid injection has been shown to have a mild to moderate reduction in pain relief but with no proven reduction in need for operative management.43
As previously described in the treatment for acute low back pain, the combination of analgesic pain control and early mobilization is the mainstay for treatment. The clinician should be diligent to detect increasing or worsening neurological function. MRI rarely is warranted in the first 4-6 weeks unless signs and symptoms of epidural compression or progressive nerve entrapment symptoms are seen.
Spinal Stenosis
Spinal stenosis is a degenerative disease of the lumbar spine that causes narrowing of the spinal canal and possibly the nerve root canal, and intervertebral foramina. This narrowing may involve just a single spinal level or multiple levels. The narrowing that results from the degenerative disease affects the spine by causing compression of vascular and neural structures. Spinal stenosis is a cause of chronic back pain that usually begins in the sixth decade and may have associated sciatica. The symptoms include low back pain that is aggravated by prolonged standing and spinal extension and is relieved by rest and forward flexion. In addition to the back symptoms, patients may complain of lower extremity pain with walking that is symptomatically similar to vascular claudication. This symptom, which is termed pseudoclaudication, occurs in approximately 60% of patients with spinal stenosis. It is called pseudoclaudication because the syndrome is typified by exercise-induced symptoms that are promptly relieved by rest, but in this case it is caused by neurologic compression, not arterial occlusion. The diagnosis of spinal stenosis is elusive as physical examination findings often are absent. The diagnosis is made by history with confirmation by CT scan or MRI. As in most cases of lumbar pain syndromes, surgery rarely is indicated. Over-the-counter analgesics provide adequate relief. Opioids may be needed and should be prescribed for short periods of time.
Epidural Compression Syndrome
Epidural compression syndrome is the collective term that includes spinal cord compression, cauda equina syndrome, and conus medullaris syndrome. While less specific, this term gives a specific description of the symptoms without a specific anatomic location, which can be important given that early symptoms falsely may localize to different spinal levels. Further, the initial management for all of these patients is the same until a specific diagnosis has been attained. These patients usually present with bilateral lower extremity symptoms, including weakness, sensory deficits, and reflex changes as well as autonomic dysfunction such as urinary retention with or without overflow incontinence, constipation followed by fecal incontinence, and diminished perineal and rectal sensation. Early in this process, these cases may present in a less-remarkable manner, yet it is the recognition of these early cases that is vital as early intervention is the key to preserving neurological and sphincteric function. These patients are to be treated aggressively and considered to have a spinal cord injury. Treatment consists of dexamethasone 10 mg to 100 mg IV at onset of evaluation.44,45 It is advised to treat these patients immediately with a dose of steroids as soon as the condition is suspected; do not wait for the results of diagnostic tests as it may take several hours to get a definitive answer and the patient should be given as good a chance of recovery as possible. However, it is crucial to understand that these recommendations are based on human studies with metastatic epidural compression that showed rapid relief of pain, as well as one animal study that demonstrated improved function.45 A dose of 10 mg of dexamethasone is reasonable in the patient who has minimal or questionable symptoms. There are no studies evaluating the utility of steroids in improving the outcome of epidural compression due to disc herniation, infection, or hemorrhage. These injuries can have long and devastating outcomes. Imaging includes plain radiographs of the potential spinal area involved and, more importantly, an emergent MRI of the cervical, thoracic, and lumbosacral spine if there is concern is for metastatic compression or infection. Otherwise a regional MRI of the spinal area affected will suffice. Immediate consultation with the appropriate specialist is required.
Spinal Infection
Spinal infections, most commonly vertebral osteomyelitis and spinal epidural abscess, are uncommon yet serious etiologies for back pain. Vertebral osteomyelitis frequently is unrecognized initially, with up to 50% of patients having symptoms for more than three months prior to their diagnosis. The history is very useful in considering the diagnosis of spinal infection. These infections occur more commonly in injection drug users, the immunocompromised, diabetics, and the elderly. Ninety percent of patients with vertebral osteomyelitis will have back pain as their primary symptom. This pain, which often is severe, commonly is nocturnal and unremitting despite appropriate rest and analgesics. Those with epidural abscess may have concomitant sciatica and neurologic symptoms. It is much less likely, although possible, that these patients will present in sepsis. In only one-half of patients will there be a marked fever. Consequently, one can not rely on the absence of fever to rule out this diagnosis. Staphylococcus aureus is the most common microbe causing infection, but E. coli, Proteus, and Pseudomonas also are known pathogens. Most of these infections are hematogenously spread and settle in the bony matrix of Batson’s venous plexus around the vertebra. The treatment for epidural abscess generally is surgery, although there are some patients who will not have surgery. This is at the discretion of the spine surgeon. The treatment for osteomyelitis is centered on IV antibiotics. Usually, 6-8 weeks of IV anti-staphylococcal antibiotics are required. It is most beneficial if blood cultures with susceptibilities are known, but for empiric treatment assume Staphylococcal involvement. For Staphylococcal coverage, consider nafcillin or cefazolin IV. If you suspect methicillin-resistant Staphylococcus aureus (MRSA) as a causative agent, vancomycin plus rifampin or linezolid is a treatment option. The antibiotic regimen may be tailored depending on the results of the blood cultures as well as the clinical response. It is important to identify the infecting organism so proper antibiotics are utilized. The remainder of treatment is supportive, including analgesics, bed rest until the symptoms improve, and immobilization with an orthosis. Surgery is reserved for those patients who have significant abscesses, spinal cord compression, significant bony destruction, or are refractory to typical medical treatment.
Back Pain in Cancer Patients
Those patients with known cancer who present with back pain present a dilemma due to the potential of spinal metastases. The best approach to these patients is to categorize them into three groups based on their symptoms.
Group I: Patients with New or Aggravated Symptoms. Group I includes those patients with new or progressing signs or symptoms of epidural compression that have been present for several hours to several days. These symptoms may include new autonomic symptoms such as urinary urgency or incontinence, bilateral paresthesias or sensory deficits, paresis, gait disturbances, absent reflexes, or the involvement of two or more nerve roots.
Treat this group as an epidural compression syndrome. They should be given immediate corticosteroid therapy, and imaged emergently with MRI.45 At the time of evaluation, these patients may not have an obvious compression syndrome, but early treatment may prevent progression of the compression and its attendant morbidity.
Group II: Patients with Stable Symptoms. Group II consists of patients with stable symptoms or signs that have been present for several days to several weeks. This includes isolated Babinski signs or radiculopathy but without other neurologic deficits or evidence of epidural compression. Radiculopathy is characterized by radicular pain, weakness, sensory changes, or reflex changes involving only one nerve root. Involvement of more than one nerve root places the patients into group I.
Evaluation and treatment are similar to those for group I. The major difference is that patients with stable symptoms do not require immediate imaging studies, although evaluation within 24 hours is advisable, if possible. The authors recommend initiating corticosteroids at the initial visit as there is little risk with one or two doses of steroid before the definitive diagnosis is determined.45
Group III: Patients with No Neurologic Signs or Symptoms. Group III includes all patients who have back pain but no neurologic signs or symptoms. These patients may be evaluated on an outpatient basis without initiating a high-dose corticosteroid regimen. Begin the diagnostic evaluation by obtaining plain radiographs of the involved spine that include anteroposterior, lateral, and oblique views.45 If any focal spinal lesions are discovered, either a CT or MRI scan of the involved area is required to examine the epidural and paraspinal spaces for possible compromise. If such involvement is found, obtain an MRI of the entire spine as there may be distant metastases without any current symptoms. It is important to understand that normal findings on plain radiographs are not completely reassuring as plain films do not rule out epidural metastases or early, small bony metastases. For example, more than 60% of patients with lymphoma and epidural metastases have normal plain radiographs.45
If the plain radiographic findings are normal but the patient’s symptoms do not resolve in 1-2 weeks, there are several options. Bone scintigraphy may be obtained, followed by a CT scan and an MRI if the scintigraphy results are abnormal. Or either a limited MRI or CT scan of the involved area may be obtained, to be followed by a full spinal MRI if there is any evidence of epidural or paraspinal space involvement. The authors recommend ordering a limited MRI in these circumstances, because it will define any epidural or paraspinal metastases as well as bony involvement. The danger in using bone scintigraphy is that one may not obtain any additional studies to examine the epidural or paraspinal spaces if the bone scan is normal. Moreover, bone scintigraphy is an intermediate step that requires confirmation if the results are abnormal; by obtaining the MRI, this intermediate stage is bypassed.
Back Pain in Children and Adolescents
Children and adolescents are much less likely to visit a physician for back pain. However, when they present with back pain, one must perform a more thorough diagnostic evaluation at the initial presentation, as there is a much higher probability of diagnosing a treatable etiology for the symptoms. The history should include all things inquired of adults. Additionally, ask about a recent increase in physical activity and involvement in sports such as football, dance, and gymnastics. These activities are associated with an increased likelihood of spondylolysis and spondylolisthesis. During the physical examination, check for the presence of birthmarks such as café au lait spots that are indicative of neurofibromatosis, as well as midline skin abnormalities of the back that may indicate underlying developmental spinal abnormalities. Etiologies to consider in the child younger than 10 years are discitis, tumor, and osteomyelitis. Etiologies for those 10 years and older include spondylolysis, spondylolisthesis, Scheuermann’s disease, tumor, vertebral osteomyelitis, herniated disk, and ankylosing spondylitis. All children without an obvious etiology for their back pain should be evaluated with a complete blood count (CBC), ESR, urinalysis, and plain spinal radiography to include oblique views if the initial AP and lateral views are normal.
Conclusion
In summary, back pain is a very common problem in adults that has a tremendous economic impact. A red flag-focused approach will allow a thorough and cost-effective evaluation. Most patients will improve in a period of weeks with analgesics and activity modification. In those who progress or fail to improve, there are other treatment options, although none has been proven most effective or even as very successful in reducing or curing symptoms. In those patients with more serious symptoms such as epidural compression of spinal infection, one needs to be aggressive in diagnosing and treating the etiology of the symptoms. Finally, those children and adolescents who present with back pain require a more thorough evaluation at the initial presentation.
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Low back pain is among the top three most common complaints seen in primary care ambulatory medicine. Affecting up to 90% of the population at some time in their lives, it is second only to upper respiratory tract infection as a symptom-related reason for primary care visits. Men and women are equally afflicted with low back pain, with a steadily increasing prevalence with age.
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