Managing Nontraumatic Acute Back Pain

Abstract

Back pain is common and costly.1Balague F. Mannion A.F. Pellise F. et al.Non-specific low back pain.Lancet. 2012; 379: 482-491Abstract Full Text Full Text PDF PubMed Scopus (1071) Google Scholar Adults with acute nontraumatic back pain account for 2% to 3% of emergency department (ED) visits.2Pitts S.R. Niska R.W. Xu J. et al.National Hospital Ambulatory Medical Care Survey: 2006 emergency department summary.Natl Health Stat Rep. 2008; : 1-38PubMed Google Scholar, 3Friedman B.W. Chilstrom M. Bijur P.E. et al.Diagnostic testing and treatment of low back pain in United States emergency departments: a national perspective.Spine. 2010; 35: E1406-1411Crossref PubMed Scopus (131) Google Scholar Although most patients’ pain has a benign, self-limited cause, a small percentage has serious pathology that, if not rapidly identified, can result in neurologic damage. Emergency physicians must develop strategies to identify the majority of patients who require nothing more than history and physical examination and identify those with serious causes while minimizing use of high-cost, time-consuming resources. Overall, the quality of supporting evidence as it specifically relates to ED patients is weak and recommendations in the article are mostly based on guidelines, expert opinion, and the author’s 33 years of clinical experience. This article will exclude interventions not typically related to the ED phase of care such as epidural steroid injections, chiropractic treatment, and acupuncture therapy. Acute, nontraumatic low back pain can be broadly divided into 3 categories: benign, self-limited musculoskeletal causes; spinal pathologies that can cause severe neurologic disability because of spinal cord or cauda equina damage; and other abdominal or retroperitoneal processes that can present with back pain. For simplicity, I will refer to these groups as simple, serious, and nonspine causes of back pain, respectively. Simple musculoskeletal causes include degenerative spine disease, muscular or ligamentous injury, and most acute disc herniations. These patients may have severe pain but have normal neurologic examination results, except for some patients with sciatica with a monoradiculopathy. Making a specific anatomic diagnosis (eg, ligamentous strain versus disc herniation) is neither helpful nor necessary because the initial management is identical and the outcomes are almost always excellent. Given a surprising paucity of ED-specific data, emergency physicians must look to national guidelines based on primary care data. Given the acuity-skewed ED population, however, they will likely encounter a larger (not precisely defined) proportion of patients with serious causes. The more common ones include metastatic epidural tumor, spinal epidural abscess, epidural hematoma, and central disc herniation (Figure 1). It is crucial to remember that although new neurologic physical findings strongly suggest serious disease, the converse is not true. Patients with any of the common serious causes can present with normal neurologic examination results—and thus be at risk for misdiagnosis.4Dugas A.F. Lucas J.M. Edlow J.A. Diagnosis of spinal cord compression in nontrauma patients in the emergency department.Acad Emerg Med. 2011; 18: 719-725Crossref PubMed Scopus (14) Google Scholar Failure to consider a serious diagnosis is the most common oversight.5Pope J.V. Edlow J.A. Avoiding misdiagnosis in patients with neurological emergencies.Emerg Med Int. 2012; 2012: 949275Crossref PubMed Google Scholar Emergency physicians must think broadly and carefully consider nonspine causes of back pain (eg, aortic aneurysm, cholangitis) (Figure 1), which will not be discussed further in this article. After history and physical examination, patients with simple back pain can be discharged from the ED, whereas those with serious back pain require advanced imaging, usually magnetic resonance imaging (MRI). Distinguishing between these 2 groups is therefore critical. The clinical examination (history and physical examination) helps make this distinction, and a few extra minutes at the bedside can save significant time by identifying patients for whom neither testing nor imaging is indicated.6Chou R. Qaseem A. Snow V. et al.Diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physicians and the American Pain Society.Ann Intern Med. 2007; 147: 478-491Crossref PubMed Scopus (1900) Google Scholar, 7Deyo R.A. Weinstein J.N. Low back pain.N Engl J Med. 2001; 344: 363-370Crossref PubMed Scopus (1526) Google Scholar, 8Goertz MTD, Bonseil J, Bonte B, et al. ARHQ guideline: adult acute and subacute low back pain. National Guideine Clearinghouse, Guideline summary NGC-9520 2012.Google Scholar The history and physical examination can identify various red flags (Figure 2), for which the evidence basis is typically weak. The best-validated ones include history of cancer, corticosteroid use, abnormal neurologic physical findings (including new ataxia and difficulty walking), and anticoagulant use.4Dugas A.F. Lucas J.M. Edlow J.A. Diagnosis of spinal cord compression in nontrauma patients in the emergency department.Acad Emerg Med. 2011; 18: 719-725Crossref PubMed Scopus (14) Google Scholar, 9Downie A. Williams C.M. Henschke N. et al.Red flags to screen for malignancy and fracture in patients with low back pain: systematic review.BMJ. 2013; 347: f7095Crossref PubMed Scopus (186) Google Scholar, 10Raison N.T. Alwan W. Abbot A. et al.The reliability of red flags in spinal cord compression.Arch Trauma Res. 2014; 3: e17850Crossref PubMed Google Scholar, 11Thiruganasambandamoorthy V. Turko E. Ansell D. et al.Risk factors for serious underlying pathology in adult emergency department nontraumatic low back pain patients.J Emerg Med. 2014; 47: 1-11Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar It is possible that combinations of red flags and interpreting them in the context of an individual patient could improve their utility. Patients with no red flags and normal neurologic examination results are at extremely low risk for serious causes of back pain. Patients with new hard neurologic findings (including a sensory level and saddle anesthesia) are at high risk for serious causes. Patients with the presence of historic red flags but normal neurologic examination results are at intermediate risk for cord or cauda equine syndrome. Management of these patients must be individualized (Figure 2). For example, back pain patients with the red flags of fever (but a presentation suggesting cholangitis) or those receiving warfarin (but whose histories suggest a lumbar muscle strain) do not need emergency MRI. On the other hand, an intravenous drug user with new back pain and unexplained fever, even with a normal neurological examination, should undergo emergency MRI. Physicians may opt to use inflammatory biomarkers or consult a neurologist to help with decisionmaking. Timing of the scan is another consideration, which is partly based on the evolution of the disease in question. Neurologic dysfunction is not always a linear progression of “compression” caused by mass effect. Patients with spinal epidural abscess can abruptly decompensate because of cord infarction from vascular thrombosis.12Darouiche R.O. Spinal epidural abscess.N Engl J Med. 2006; 355: 2012-2020Crossref PubMed Scopus (476) Google Scholar Patients with metastatic spine disease can also deteriorate abruptly because of vertebral collapse with acute compression.13Cole J.S. Patchell R.A. Metastatic epidural spinal cord compression.Lancet Neurol. 2008; 7: 459-466Abstract Full Text Full Text PDF PubMed Scopus (278) Google Scholar Therefore, even in neurologically intact patients, there is more urgency for the MRI if spinal epidural abscess is the target diagnosis and slightly less urgency if cancer is the major concern. Finally, disposition (inpatient versus outpatient) must also be considered. Social factors, availability of a primary care physician, potential availability of next-morning MRI or neurologic consultation, and the specific differential diagnosis all factor into these decisions. Routine laboratory testing is not useful. Elevated WBC counts are found in only two thirds of patients with spinal epidural abscess.12Darouiche R.O. Spinal epidural abscess.N Engl J Med. 2006; 355: 2012-2020Crossref PubMed Scopus (476) Google Scholar Inflammatory markers such as erythrocyte sedimentation rate (ESR) or C-reactive protein are highly sensitive but nonspecific markers for epidural abscess and, to a lesser extent, cancer.12Darouiche R.O. Spinal epidural abscess.N Engl J Med. 2006; 355: 2012-2020Crossref PubMed Scopus (476) Google Scholar, 14Davis D.P. Salazar A. Chan T.C. et al.Prospective evaluation of a clinical decision guideline to diagnose spinal epidural abscess in patients who present to the emergency department with spine pain.J Neurosurg Spine. 2011; 14: 765-770Crossref PubMed Scopus (67) Google Scholar, 15Deyo R.A. Diehl A.K. Cancer as a cause of back pain: frequency, clinical presentation, and diagnostic strategies.J Gen Intern Med. 1988; 3: 230-238Crossref PubMed Scopus (195) Google Scholar The problem is the threshold. An ESR of greater than 20 mm/hour has a sensitivity approaching 100% for epidural abscess (but with poor specificity); as one increases the threshold, the specificity improves but at the price of decreased sensitivity.14Davis D.P. Salazar A. Chan T.C. et al.Prospective evaluation of a clinical decision guideline to diagnose spinal epidural abscess in patients who present to the emergency department with spine pain.J Neurosurg Spine. 2011; 14: 765-770Crossref PubMed Scopus (67) Google Scholar A single-institution study of patients with suspected spinal epidural abscess compared clinical outcomes before and after implementation of a guideline using ESR (cutoff of 20 mm/hour) and C-reactive protein. Diagnostic delays decreased from 84% to 10%, and the proportion of patients with motor abnormalities at diagnosis decreased from 82% to 19%.14Davis D.P. Salazar A. Chan T.C. et al.Prospective evaluation of a clinical decision guideline to diagnose spinal epidural abscess in patients who present to the emergency department with spine pain.J Neurosurg Spine. 2011; 14: 765-770Crossref PubMed Scopus (67) Google Scholar ESR performed better than C-reactive protein in this small study. Using ESR for patients with possible metastatic cancer to the spine has a lower sensitivity (78% with a cutoff of 20 mm/hour).15Deyo R.A. Diehl A.K. Cancer as a cause of back pain: frequency, clinical presentation, and diagnostic strategies.J Gen Intern Med. 1988; 3: 230-238Crossref PubMed Scopus (195) Google Scholar Because of poor specificity, ESR and C-reactive protein are not recommended for patients without red flags, and because of poor sensitivity, they are not useful for patients when disc herniation or epidural hematoma is the main diagnostic consideration. Better-quality evidence derived from primary care populations underlies the recommendations against routine imaging of patients with simple back pain.1Balague F. Mannion A.F. Pellise F. et al.Non-specific low back pain.Lancet. 2012; 379: 482-491Abstract Full Text Full Text PDF PubMed Scopus (1071) Google Scholar, 6Chou R. Qaseem A. Snow V. et al.Diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physicians and the American Pain Society.Ann Intern Med. 2007; 147: 478-491Crossref PubMed Scopus (1900) Google Scholar, 8Goertz MTD, Bonseil J, Bonte B, et al. ARHQ guideline: adult acute and subacute low back pain. National Guideine Clearinghouse, Guideline summary NGC-9520 2012.Google Scholar In actual ED practice, more than 30% of patients with nontraumatic back pain are imaged, possibly reflecting the skewed acuity. Over time, there has been a strong trend toward computed tomography (CT) or MRI.3Friedman B.W. Chilstrom M. Bijur P.E. et al.Diagnostic testing and treatment of low back pain in United States emergency departments: a national perspective.Spine. 2010; 35: E1406-1411Crossref PubMed Scopus (131) Google Scholar A meta-analysis of 1,804 patients from 6 studies who received no imaging versus those with any imaging (spine radiographs or MRI) found no difference in outcomes.16Chou R. Fu R. Carrino J.A. et al.Imaging strategies for low-back pain: systematic review and meta-analysis.Lancet. 2009; 373: 463-472Abstract Full Text Full Text PDF PubMed Scopus (414) Google Scholar Another study randomized 380 back pain patients (whose physicians had ordered radiographs) to radiographs versus MRI.17Jarvik J.G. Hollingworth W. Martin B. et al.Rapid magnetic resonance imaging vs radiographs for patients with low back pain: a randomized controlled trial.JAMA. 2003; 289: 2810-2818Crossref PubMed Scopus (276) Google Scholar Use of MRI did not improve outcomes, but costs trended higher in the MRI group, in part because of increased numbers of procedures based on abnormal MRI findings that are often incidental; fully 52% of asymptomatic individuals with no history of back pain have disc bulges and 27% have disc protrusions.18Jensen M.C. Brant-Zawadzki M.N. Obuchowski N. et al.Magnetic resonance imaging of the lumbar spine in people without back pain.N Engl J Med. 1994; 331: 69-73Crossref PubMed Scopus (1861) Google Scholar In patients with red flags, radiographs should not be used to distinguish simple from serious back pain because negative radiograph results are insufficient to exclude serious pathology and positive ones require follow-up MRI anyway. Application of heat is weakly recommended.1Balague F. Mannion A.F. Pellise F. et al.Non-specific low back pain.Lancet. 2012; 379: 482-491Abstract Full Text Full Text PDF PubMed Scopus (1071) Google Scholar, 6Chou R. Qaseem A. Snow V. et al.Diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physicians and the American Pain Society.Ann Intern Med. 2007; 147: 478-491Crossref PubMed Scopus (1900) Google Scholar Rapid resumption of ordinary activity leads to faster, better outcomes than bed rest.19Malmivaara A. Hakkinen U. Aro T. et al.The treatment of acute low back pain—bed rest, exercises, or ordinary activity?.N Engl J Med. 1995; 332: 351-355Crossref PubMed Scopus (559) Google Scholar If the patient obtains relief from bed rest, a short duration (2 days) results in faster recovery than longer courses.6Chou R. Qaseem A. Snow V. et al.Diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physicians and the American Pain Society.Ann Intern Med. 2007; 147: 478-491Crossref PubMed Scopus (1900) Google Scholar, 7Deyo R.A. Weinstein J.N. Low back pain.N Engl J Med. 2001; 344: 363-370Crossref PubMed Scopus (1526) Google Scholar, 20Deyo R.A. Diehl A.K. Rosenthal M. How many days of bed rest for acute low back pain? a randomized clinical trial.N Engl J Med. 1986; 315: 1064-1070Crossref PubMed Scopus (361) Google Scholar Acutely, exercise is not recommended.1Balague F. Mannion A.F. Pellise F. et al.Non-specific low back pain.Lancet. 2012; 379: 482-491Abstract Full Text Full Text PDF PubMed Scopus (1071) Google Scholar, 6Chou R. Qaseem A. Snow V. et al.Diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physicians and the American Pain Society.Ann Intern Med. 2007; 147: 478-491Crossref PubMed Scopus (1900) Google Scholar Guidelines and expert opinion recommend non-narcotic analgesics.1Balague F. Mannion A.F. Pellise F. et al.Non-specific low back pain.Lancet. 2012; 379: 482-491Abstract Full Text Full Text PDF PubMed Scopus (1071) Google Scholar, 6Chou R. Qaseem A. Snow V. et al.Diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physicians and the American Pain Society.Ann Intern Med. 2007; 147: 478-491Crossref PubMed Scopus (1900) Google Scholar, 7Deyo R.A. Weinstein J.N. Low back pain.N Engl J Med. 2001; 344: 363-370Crossref PubMed Scopus (1526) Google Scholar Despite numerous studies and recommendations, there are few data that inform the best pharmacotherapy for the initial treatment of ED patients with acute back pain. We do not know whether, overall, ED patients have more severe pain than the primary care patients for which these guidelines were developed. In practice, emergency physicians commonly use opioids (61% in a large national sample).3Friedman B.W. Chilstrom M. Bijur P.E. et al.Diagnostic testing and treatment of low back pain in United States emergency departments: a national perspective.Spine. 2010; 35: E1406-1411Crossref PubMed Scopus (131) Google Scholar Muscle relaxants (prescribed by emergency physicians for 41% of back pain patients) are effective, although they often cause sedation.3Friedman B.W. Chilstrom M. Bijur P.E. et al.Diagnostic testing and treatment of low back pain in United States emergency departments: a national perspective.Spine. 2010; 35: E1406-1411Crossref PubMed Scopus (131) Google Scholar, 21van Tulder M.W. Touray T. Furlan A.D. et al.Muscle relaxants for nonspecific low back pain: a systematic review within the framework of the cochrane collaboration.Spine. 2003; 28: 1978-1992Crossref PubMed Scopus (171) Google Scholar Oral steroids do not help unselected patients with acute back pain, but the subset of patients with an acute radiculopathy may benefit.22Balakrishnamoorthy R. Horgan I. Perez S. et al.Does a single dose of intravenous dexamethasone reduce Symptoms in Emergency Department Patients With Low Back Pain and Radiculopathy (SEBRA)? a double-blind randomised controlled trial.Emerg Med J. 2015; 32: 525-530Crossref PubMed Scopus (17) Google Scholar, 23Eskin B. Shih R.D. Fiesseler F.W. et al.Prednisone for emergency department low back pain: a randomized controlled trial.J Emerg Med. 2014; 47: 65-70Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar My approach prioritizes treating pain and recognizes that the guidelines allow some variation. For patients with severe pain, I recommend 2 to 3 days of bed rest with rapid resumption of normal activity thereafter, treatment for 2 to 3 days with opioid analgesics, acetaminophen, and a muscle relaxant. Simultaneously, I prescribe a longer course of ibuprofen to the patient and I emphasize the importance of using an anti inflammatory medication. For patients with less severe pain, I omit the bed rest and the opioids. I recommend follow-up with a primary care physician within 1 to 2 weeks and give careful instructions about symptoms for which to return sooner (red flags). Patient satisfaction seems to be more related to their perception that a careful history and physical examination have been conducted and that the provider has clearly explained the diagnosis and care plan rather than to receiving imaging.24Carey T.S. Garrett J. Jackman A. et al.The outcomes and costs of care for acute low back pain among patients seen by primary care practitioners, chiropractors, and orthopedic surgeons. The North Carolina Back Pain Project.N Engl J Med. 1995; 333: 913-917Crossref PubMed Scopus (474) Google Scholar Classic presentations are frequently absent and symptoms and signs may evolve with time, even during the ED encounter. Many patients with cauda equina syndrome do not have rectal or urinary sphincter dysfunction or saddle anesthesia on presentation.25Balasubramanian K. Kalsi P. Greenough C.G. et al.Reliability of clinical assessment in diagnosing cauda equina syndrome.Br J Neurosurg. 2010; 24: 383-386Crossref PubMed Scopus (75) Google Scholar, 26Domen P.M. Hofman P.A. van Santbrink H. et al.Predictive value of clinical characteristics in patients with suspected cauda equina syndrome.Eur J Neurol. 2009; 16: 416-419Crossref PubMed Scopus (48) Google Scholar Only approximately 10% of patients with spinal epidural abscess present with the classic triad of fever, back pain, and neurologic deficits.27Davis D.P. Wold R.M. Patel R.J. et al.The clinical presentation and impact of diagnostic delays on emergency department patients with spinal epidural abscess.J Emerg Med. 2004; 26: 285-291Abstract Full Text Full Text PDF PubMed Scopus (220) Google Scholar Only 66% of patients have fever at presentation.28Reihsaus E. Waldbaur H. Seeling W. Spinal epidural abscess: a meta-analysis of 915 patients.Neurosurg Rev. 2000; 23 (discussion 5): 175-204Crossref PubMed Scopus (605) Google Scholar Although most patients with metastatic epidural spinal cord compression have a history of cancer, in approximately 20%, the vertebral metastasis is the first evidence of the cancer.13Cole J.S. Patchell R.A. Metastatic epidural spinal cord compression.Lancet Neurol. 2008; 7: 459-466Abstract Full Text Full Text PDF PubMed Scopus (278) Google Scholar In a meta-analysis of 613 patients with spinal epidural hematoma, 30% of patients had no identifiable reason for the bleeding.29Kreppel D. Antoniadis G. Seeling W. Spinal hematoma: a literature survey with meta-analysis of 613 patients.Neurosurg Rev. 2003; 26: 1-49Crossref PubMed Scopus (456) Google Scholar Because some patients may not have a history of red flags, careful examination of the lower extremities and perineum is extremely important, including testing sensation in the feet and Babinski’s sign. Other than a monoradiculopathy from sciatica, new hard physical findings should drive rapid evaluation (Figure 2). Although a rectal examination is not required for all patients with back pain, testing for saddle anesthesia, which is a sensitive finding in cauda equina syndrome, should be conducted routinely.25Balasubramanian K. Kalsi P. Greenough C.G. et al.Reliability of clinical assessment in diagnosing cauda equina syndrome.Br J Neurosurg. 2010; 24: 383-386Crossref PubMed Scopus (75) Google Scholar For patients with urinary symptoms, a postvoid residual of greater than 100 mL by ultrasonography or bladder scanning is abnormal. Although the majority of patients without red flags and with normal neurologic examination results have simple back pain, the occasional serious causes will be extremely difficult to diagnose at initial presentation. Therefore, follow-up with another physician in 1 to 2 weeks, or sooner if red flag symptoms develop, is a very important instruction to give to the patient. Patients with back pain and new neurologic findings (other than a monoradiculopathy consistent with sciatica) should undergo emergency MRI. Figure 3 is an MRI checklist that highlights key issues to help facilitate the study, including areas of the spine to be imaged, the use of contrast, and the need for sedation. In general, patients who require emergency scanning should be transferred if MRI is not available at a given hospital. However, if a qualified local spine surgeon were willing to operate according to results of CT scanning, performing a CT would be a reasonable alternative. If the CT result were normal, an MRI would still be needed. These decisions should be individualized. For high-risk patients with negative MRI results, physicians should reevaluate the situation. Discuss the clinical findings with the radiologist to help them focus to the clinically relevant area of spine. Reexamine the patient to confirm the initial findings (and to evaluate for evolution). Finally, consider lumbar puncture (to help diagnose transverse myelitis or Guillain-Barré syndrome) and neurology consultation to help clarify the diagnosis. Definitive treatment for patients with diagnostic MRI requires spine surgical consultation and is beyond the purview of emergency medicine, though some issues should be addressed in the ED (Figure 4).