ACR Appropriateness Criteria®
Clinical Condition: Acute Low Back Pain
Variant 1: Uncomplicated. No red flags. (Red flags defined in the text below.)
Radiologic Exam Procedure |
Appropriateness Rating |
Comments |
X-ray, lumbar spine |
2 |
|
NUC, bone scan |
2 |
|
CT, lumbar spine, without contrast |
2 |
|
Myelogram |
2 |
Usually done in conjunction with CT. |
Myelogram/CT |
2 |
Usually accompanied by plain film myelogram. |
MRI, lumbar spine, without contrast |
2 |
|
MRI, lumbar spine, with and without contrast |
2 |
|
Appropriateness Criteria Scale
1 2 3 4 5 6 7 8 9
1 = Least appropriate 9 = Most appropriate
|
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 2: Low velocity trauma, osteoporosis, and/or age > 70.
Radiologic Exam Procedure |
Appropriateness Rating |
Comments |
MRI, lumbar spine, without contrast |
8 |
|
X-ray, lumbar spine |
6 |
|
CT, lumbar spine, without contrast |
6 |
MRI preferred. CT useful if MRI contraindicated or unavailable. |
NUC, bone scan |
4 |
|
MRI, lumbar spine, with and without contrast |
3 |
|
Myelogram |
1 |
Usually done in conjunction with CT. |
Myelogram/CT |
1 |
Usually accompanied by plain film myelogram. |
Appropriateness Criteria Scale
1 2 3 4 5 6 7 8 9
1 = Least appropriate 9 = Most appropriate
|
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 3: Suspicion of cancer, infection, or immunosuppression.
Radiologic Exam Procedure |
Appropriateness Rating |
Comments |
MRI, lumbar spine, without contrast |
8 |
|
MRI, lumbar spine, with and without contrast |
7 |
|
X-ray, lumbar spine |
5 |
|
NUC, bone scan |
5 |
|
CT, lumbar spine, without contrast |
4 |
|
Myelogram |
2 |
Usually done in conjunction with CT. |
Myelogram/CT |
2 |
Usually accompanied by plain film myelogram. |
Appropriateness Criteria Scale
1 2 3 4 5 6 7 8 9
1 = Least appropriate 9 = Most appropriate
|
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 4: Radiculopathy.
Radiologic Exam Procedure |
Appropriateness Rating |
Comments |
MRI, lumbar spine, without contrast |
8 |
|
Myelogram/CT |
5 |
MRI preferred. May be indicated if MRI contraindicated or nondiagnostic. Usually accompanied by plain film myelogram. |
CT, lumbar spine, without contrast |
5 |
|
MRI, lumbar spine, with and without contrast |
5 |
Indicated if noncontrast MRI nondiagnostic or confusing. |
X-ray, lumbar spine |
3 |
|
NUC, bone scan |
2 |
|
Myelogram |
2 |
Usually done in conjunction with CT. |
Appropriateness Criteria Scale
1 2 3 4 5 6 7 8 9
1 = Least appropriate 9 = Most appropriate
|
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 5: Prior lumbar surgery.
Radiologic Exam Procedure |
Appropriateness Rating |
Comments |
MRI, lumbar spine, with and without contrast |
8 |
Differentiate disc versus scar. |
MRI, lumbar spine, without contrast |
6 |
Contrast often necessary. |
CT, lumbar spine, without contrast |
6 |
Most useful in post fusion patients or when MRI contraindicated or confusing. |
NUC, bone scan |
5 |
Helps detect and localize painful pseudoarthrosis. |
X-ray, lumbar spine |
5 |
Flex/extension may be useful. |
Myelogram/CT |
5 |
Usually accompanied by plain film myelogram. |
Myelogram |
2 |
Usually done in conjunction with CT. |
Appropriateness Criteria Scale
1 2 3 4 5 6 7 8 9
1 = Least appropriate 9 = Most appropriate
|
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 6: Cauda equina syndrome.
Radiologic Exam Procedure |
Appropriateness Rating |
Comments |
MRI, lumbar spine, without contrast |
9 |
Use of contrast depends on clinical circumstances. |
MRI, lumbar spine, with and without contrast |
8 |
Use of contrast depends on clinical circumstances. |
Myelogram/CT |
6 |
Useful if MRI nondiagnostic or contraindicated. Usually accompanied by plain film myelogram. |
CT, lumbar spine, with and without contrast |
4 |
May be indicated if MRI is confusing or contraindicated and myelography not feasible. Use of contrast depends on clinical circumstances. |
X-ray, lumbar spine |
3 |
|
Myelogram |
2 |
Usually done in conjunction with CT. |
NUC, bone scan |
2 |
|
Appropriateness Criteria Scale
1 2 3 4 5 6 7 8 9
1 = Least appropriate 9 = Most appropriate
|
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Acute low back pain (LBP) with or without radiculopathy (pain radiating down the leg[s]) is one of the most common health problems in the United States and is the leading cause of disability for persons younger than age 45. The cost of evaluating and treating acute LBP runs into billions of dollars annually, not including time lost from work.
Because of the high prevalence and high cost of dealing with this problem, government agencies have sponsored extensive studies that are now part of the growing body of literature on this subject. One of the earlier comprehensive studies was carried out in Quebec and was reported in the journal Spine in 1987. The U.S. Department of Health and Human Services convened a 23-member multidisciplinary panel of experts to review all of the literature on this subject, grade it, and develop a "Clinical Practice Guideline," which was published in December 1994. States have also convened similar panels in recent years, largely because of the rapidly rising workers' compensation claim burden being imposed on state budgets by LBP management.
It is now clear from the above studies that uncomplicated acute LBP is a benign, self-limited condition that does not warrant any imaging studies. The vast majority of these patients are back to their usual activities within 30 days. The challenge for the clinician, therefore, is to distinguish that small segment within this large patient population that should be evaluated further because of suspicion of a more serious problem.
Indications of a more complicated status, often termed "red flags," include the following:
- Recent significant trauma, or milder trauma, age >50
- Unexplained weight loss
- Unexplained fever
- Immunosuppression
- History of cancer
- Intravenous (IV) drug use
- Prolonged use of corticosteroids, osteoporosis
- Age >70
- Focal neurologic deficit progressive or disabling symptoms
- Duration greater than 6 weeks
Radiographs:
Radiographs are recommended when any of the above red flags are present. Lumbar radiography may be sufficient for the initial evaluation of these red flags:
- Recent significant trauma (at any age)
- Osteoporosis
- Age >70
The initial evaluation of the LBP patient may require further imaging if red flags such as suspicion of cancer or infection are present.
Isotope Bone Scan
The role of the isotope bone scan in patients with acute LBP has changed in recent years with the wide availability of MRI and especially contrast-enhanced MRI. The bone scan is a moderately sensitive test for detecting the presence of tumor, infection, or occult fractures of the vertebrae but not for specifying the diagnosis. The yield is very low in the presence of normal radiographs and laboratory studies and highest for patients with known malignancy. The test is contraindicated in pregnancy.
High-resolution isotope imaging including single photon emission computed tomography (SPECT), may localize the source of pain in patients with articular facet osteoarthritis prior to therapeutic facet injection. Similar scans may be helpful in detecting and localizing the site of painful pseudoarthrosis in patients following lumbar spinal fusion.
Plain and contrast-enhanced MRI has the ability to demonstrate inflammatory, neoplastic, and most traumatic lesions as well as show anatomic detail not available on isotope studies. Gadolinium-enhanced MRI reliably shows the presence and extent of spinal infection, and is useful in assessing therapy. MRI has therefore taken over the role of the isotope scan in many cases where the location of the lesion is known. The isotope scan remains invaluable when a survey of the entire skeleton is indicated (e.g., for metastatic disease).
Magnetic Resonance Imaging, Computed Tomography (CT), Myelography, Myelography/CT
Uncomplicated acute LBP (no red flags) does not warrant the use of any of this imaging studies. The early indiscriminate use of expensive imaging procedures in this common clinical setting has caused large increases in worker's compensation costs and in some cases has led to the perception that CT and MRI of the lumbar spine are not worth the cost. Adding to this controversy is the fact that nonspecific lumbar disc abnormalities are common, and can be demonstrated readily on myelography, CT, and MRI, even in asymptomatic patients.
The appropriate use of these imaging procedures is an important challenge that has been extensively addressed in the major reviews referenced herein (see the original guideline). For example, LBP complicated by "red flags" suggesting infection or tumor may justify early use of CT or MRI even if radiographs are negative. The most common indication for the use of these imaging procedures, however, is the clinical setting of LBP complicated by radiating pain (radiculopathy, sciatica) or cauda equina syndrome (bilateral leg weakness, urinary retention, saddle anesthesia), usually due to herniated disc and/or canal stenosis.
Magnetic Resonance Imaging
MRI of the lumbar spine has become the initial imaging modality of choice in complicated LBP, displacing myelography and CT in recent years. MRI is particularly efficacious for detecting "red flag" diagnoses, particularly using the STIR and fat-saturated T2 fast-spin-echo sequences. MR with contrast is useful for suspected infection and neoplasia. In postop patients, enhanced MRI allows distinction between disc and scar when there is extension of tissue beyond the interspace.
Computed Tomography
CT scans provide superior bone detail but are not quite as useful in depicting disc protrusions when compared with multiplanar MRI. With the added value associated with high quality reformatted sagittal and coronal plane images, CT is useful for depiction of spondylolysis, pseudoarthrosis, scoliosis, and for post-surgical evaluation of bone graft integrity, surgical fusion, and instrumentation.
Myelography/CT
"Plain" myelography was the mainstay of lumbar herniated disc diagnosis for decades. It is now usually combined with post-myelography CT. The combined study is complementary to plain CT or MRI and occasionally more accurate in diagnosing disc herniation, but suffers the disadvantage of requiring lumbar puncture and contrast injection. It may also be useful in surgical planning.
Thermography, Discography, CT Discography
Expert panels agreed that these imaging modalities were either too nonspecific (thermography) or carried additional risk (discography) not warranted in view of the efficacy of other less invasive imaging procedures. When other studies fail to localize the cause of pain, discography may occasionally be helpful. Although the images often depict nonspecific aging or degenerative changes, the injection itself may reproduce the patient's pain, which may have diagnostic value.
Abbreviations
- CT, computed tomography
- MRI, magnetic resonance imaging
- NUC, nuclear imaging