Lumbar Imaging

The purpose of this blog is to examine the relationship between low back pain and medical imaging. We will discuss low back pain, the prevalence of lumbar imaging, current imaging guidelines, as well as major concerns with the use of routine medical imaging (for low back pain).

Low Back Pain

Low back pain is a common symptom experienced by more than 540 million people at any one time. Think about that for a second…540 million men and women, of various ages, are currently limited in their ability to perform desired activities due to the presence of low back pain [1,2]. This number is remarkably high, and its consequences are affecting more than just functional abilities, as the social participation and financial well-being of individuals are impacted as well [1].

But what exactly is low back pain?

One way to define low back pain is by its location. This is described by pain in the area below the 12th rib and above the buttock creases, and may contain pain and/or neurological symptoms in one or both legs [1,3].

When someone experiences pain in this area, they often want to know why they have pain. What is wrong? What is the actual source of pain?

Enter the topic of medical imaging.

Lumbar imaging provides us with a snapshot of the current structural state of an individual’s spine. While this can be helpful in certain cases (more on this later), the routine use of medical imaging in the management of low back pain has come into question.

Do we need this information to effectively manage an individual with low back pain? How relevant are the findings as they relate to an individual’s pain experience? Will the results alter clinical outcomes? How accurate are these image readings?

Let’s take a look.

Imaging Prevalence and Guidelines

If someone were to present to a general practitioner with complaints of low back pain, odds are favorable that said individual would be referred for lumbar imaging. This has been widely demonstrated across various countries:

  • USA: 54% of patients demonstrating no red flags were referred for imaging [5].
  • Norway: 39% of patients experiencing low back pain were referred for imaging [6].
  • Italy: 56% of patients who presented to the Emergency Department with low back pain were referred for imaging [7].
  • India: 100% of patients (n=251) with chronic low back pain, underwent imaging [8].
  • China: 41% of patients (n=3107) received MRI for due to simple back pain [9].
  • Brazil: 70% of rheumatologists order imaging on first visit if patient has acute low back pain [10].

At first glance, these statistics may not mean much, but if we look at current recommendations for the use of lumbar imaging, it should shed a different light on these numbers.

Current guidelines recommend that lumbar imaging be reserved for those individuals whom the results would change management. This means, lumbar imaging should only occur if the clinician suspects a specific condition that would require different management (i.e significant pathology, such as malignancy or fracture) [2].

These guidelines have been established across multiple societies (i.e American Chiropractic Association, American College of Physicians, North American Spine Society) and is the current recommendation for clinicians and patients, as established by the Choosing Wisely campaign [11].

Furthermore, if we look at the prevalence of significant pathologies, research demonstrates that serious spinal pathologies are rare (less than 1%) in individuals who present to a primary care provider with complaints of low back pain [12,13, 34].

Now re-read the referral statistics listed above.

Despite guidelines to reserve the use of lumbar imaging for serious conditions, routine lumbar imaging continues to be overutilized.

When is imaging warranted?

This information is not to suggest lumbar imaging is unnecessary. As stated in the guidelines, there are times where medical imaging will be warranted and advisable for those experiencing low back pain. The determining factor is whether or not the management of the individual would change. Examples of such cases include clinical suspicion of sinister pathological cause, which may be triggered by the presence of red flags during a clinical exam.

Some examples of red flags include, but are not limited to:

  • Patient medical history (i.e was there trauma or a fall? Prolonged use of corticosteroids? A history of cancer?) [12].
  • Lumbar or sacral dermatome changes (hypoesthesia, hyperesthesia or anesthesia) [14].
  • Lower extremity weakness or hyporeflexia [14].
  • Bowel and bladder changes [14].

These, or other components of a clinical assessment, may raise suspicion of pathological cause(s) of an individual’s low back pain. Some of these major conditions include, but are not limited to:

  • Spinal fracture (1.8-4.3%)
  • Malignancy (0.2%)
  • Infection (0.01%)
  • Cauda equina syndrome (0.04%)

Lumbar imaging will be warranted in particular cases, however, as stated previously, these incidents are rare (less than 1% of all low back cases) [12,13,34]. So if clear guidelines exist, but imaging rates are still high, why continue to provide routine lumbar imaging?

Prevalence in Asymptomatic Populations

Guideline negligence and the frequent use of routine lumbar imaging are influenced by a variety of factors, but one of the most substantial influences stem from the need of a biomedical diagnosis [15]. People want to know “what is the cause of my pain?”, so what better way than to provide them with visual evidence via an image, right?

The patients hope is that lumbar imaging, either through X-ray, MRI, or CT, will prove the existence of a structural abnormality, and thus the root cause of their pain has been discovered.

However, the detection of structural irregularities on lumbar imaging is not a sole determinant of pain, as these abnormalities have been found on a wide variety of populations without pain.

In 1990, Boden et al. looked at 67 individuals who reported no history of low back pain. Of these 67 subjects, there were lumbar MRI abnormalities found in 28% of them [16].

A few years later, Jensen et al conducted a similar study, using a slightly larger population, which included 98 individuals, all of which reported no history of low back pain. MRI results showed disk abnormalities in 64% of these individuals! Disk bulges and protrusions were most prevalent, as they were found in 52% and 27% of the subjects, respectively, and were most common at the L4-L5 and L5-S1 levels [17].

Both Boden and Jensen concluded that the findings on lumbar imaging may be nothing more than coincidental, and practitioners should caution against implementing treatment strategies based solely on the results of lumbar imaging.

In a more recent review done by Brinjiski in 2014, 33 studies (including the Jensen and Boden studies listed above) were examined, which consisted of imaging findings for 3110 asymptomatic individuals. Structural findings observed included disk degeneration, disk signal loss, disk height loss, disk bulge, disk protrusion, annular fissure, facet degeneration, and spondylolisthesis among men and women from 20-80 years old. A few common themes were found:

  • Up to 50% of asymptomatic individuals from ages 30-39 show signs of disc degeneration, loss of disk height, or disk bulges.
  • There was an increase in prevalence of abnormal findings with an increase in age (linear correlation).
  • Disk degeneration prevalence was 37% in 20 year olds, and increased to 96% in 80 year olds.
  • Disk height loss and disk bulge prevalence showed an increase in roughly 1% each year.
  • Facet degeneration and spondylolisthesis were not common in younger ages, but became more prevalent in older ages.

Brinjikji went on to conclude, “our study suggests that imaging findings of degenerative changes are generally part of the normal aging process rather than pathologic processes requiring intervention” [18].

By concluding these abnormalities are “part of the normal aging process,” we can view these changes as no different than how our skin gets wrinkles and our hair turns gray as we age.

Clinical Outcomes

We now know if someone were to get an image of their low back, chances are some degree of abnormalities probably exist. We also know these findings can be irrelevant on its own. So why continue to provide routine imaging for those with low back pain? Does it provide value to the patient or improve clinical outcomes?

Multiple studies have reported those patients with low back pain who underwent early lumbar imaging showed no better health outcomes when compared to no imaging or delayed imaging groups. Various health outcomes measured included pain, function, quality of life, and overall improvement [19-26].

In addition to not altering clinical outcomes, early imaging has also been shown to have a negative consequence on health care costs and absence from work [27].

Total medical costs were reported to be significantly higher for groups receiving early MRI versus not receiving an MRI. These early MRI groups also demonstrated an increased rate of surgery, injection, and average outpatient visits (compared to no-MRI groups), thus contributing to total overall healthcare cost and potential for future disability [28,29].

Finally, those individuals who underwent early MRI reported having a higher rate of absence from work compared to the no-MRI group. In a study by Webster and Cifuentes, early MRI group reported a mean absence from work of 133.6 days versus 22.9 days by the no-MRI group. In another study by Webster, the no-MRI group reported a 68% lower rate of absence of work [28,30].

Radiologist Interpretation

The final topic we will discuss on lumbar imaging is about the consistency of readings between various readers. While this information does not provide a strong argument for or against lumbar imaging, it is simply another piece of information to understand.

In two different studies done by Arana (2010 and 2011), intraobserver (between same observer) and interobserver (between multiple observers) reliability was measured between radiologists when interpreting lumbar images of patients with low back pain.

In 2010, Arana had 5 radiologists interpret the results of 53 patients with low back pain, assessing Modic changes, osteophytes, Schmorl nodes, diffuse defects, disk degeneration, annular tears, disk contour, spondylolisthesis, and spinal stenosis. The results demonstrated intraobserver reliability was substantial (k statistic 0.61-0.80) for most findings, while interobserver reliability was moderate (k statistic 0.41-0.60) [31].

In 2011, Arana did a similar study, using 5 radiologists to interpret 53 patients with low back pain. However this time, the radiologists were asked to interpret images based off two different nomenclatures and the findings focused on intervertebral herniations and disc contour. The results were similar as before, as intraobserver reliability was substantial (k statistic 0.61-0.80) for both herniations and contour, while interobserver reliability was only moderate (k statistic 0.41-0.60) for herniations and fair to moderate (k statistic 0.21-.0.60) for contour [32].

These studies demonstrate a difference in interpretation of lumbar imaging among various radiologists, suggesting “only moderate agreement can realistically be expected in routine practice” [31,32].

Conclusion

Even with current guidelines recommending the reduction in routine lumbar imaging, rates continue to be high, which contributes to a cascade effect of increased healthcare costs and time away from work. While the use of lumbar imaging in the management of low back pain can be appropriate at times, the occurrence rate of these cases are quite rare [12,13].

With all the information gathered on low back pain and imaging, it has been shown that the actual source of pain cannot be accurately identified in a majority of people, therefore most low back pain cases are labeled as non-specific [4].

This ties into the notion that low back pain is better defined as a symptom, rather than a disease. Instead of looking through a purely biomedical lens (i.e. L5-S1 disk bulge as source of pain), we are becoming more aware of the psychological, social, and biophysical factors that impact an individual’s pain experience [1].

A better understanding of the multifactorial nature of pain has led to a shift in our treatment approach, as guidelines now recommend the use of a biopsychosocial model for assessment and management of non specific low back pain [2]. This transition away from a strict biomedical framework (removing medical labels as the cause of pain), allows us to emphasize treatment on the individual rather than a diagnosis.

So, instead of placing emphasis on visual evidence and medical labels acquired from an image, practitioners should focus on reassuring patients they do not have a serious disease, build confidence that symptoms will improve over time (as most low back pain will self resolve in 6-8 weeks), encourage them to stay active, avoid bed rest, and promote participation in work and meaningful activities [33, 35].

Disclaimer

The information provided is NOT medical advice. It is for entertainment purposes only.

References

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