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Longitudinal associations between incident lumbar spine MRI findings and chronic low back pain or radicular symptoms: retrospective analysis of data from the longitudinal assessment of imaging and disability of the back (LAIDBACK)

PainSci » bibliography » Suri et al 2014
Tags: etiology, diagnosis, biomechanics, back pain, counter-intuitive, imaging, good news, spine, pro, pain problems

PainSci commentary on Suri 2014: ?This page is one of thousands in the bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided wherever possible.

The link between MRI findings and back pain is surprisingly loose in general, as established by many studies over decades (eg from Weber 1983 to Brinjikji 2015). But what if you were more specific? Studies like that have mostly failed to look for a link between new findings and new symptoms; and they haven’t distinguished between back pain and neurological symptoms in the legs (sciatica). This lack of precision “may obscure real and important biological relationships,” so this study was intended to “address this gap in the literature.”

Basically, they found 123 people who were just fine, and checked in with them occasionally over the next three years and scanned their backs. This was a great idea, the paper is well-written and thoughtful, and I’d love to see similar but bigger studies in the future.

They found new MRI findings in just five people over that three years (which undermines the statistical power of the results). They may also have missed some new findings as well (the MRIs weren’t frequent enough, basically). Nevertheless, there’s some really useful data here. Some signs were consistently linked to new symptoms of the sort you’d expected — eg nerve root compression causing sciatica — but they were rare, and the link “at best explains only a very small proportion” of new symptoms. Most importantly, many new symptoms were not associated with any new MRI findings: “the overwhelming majority of individuals with new radicular symptoms will not have relevant new MRI findings.”

As physical therapist and sciatica expert Tom Jesson wrote of this result: “It seems that asymptomatic extrusions aren’t a big thing.” Indeed.

~ Paul Ingraham

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

BACKGROUND: There are few longitudinal cohort studies examining associations between incident MRI findings and incident spine-related symptom outcomes. Prior studies do not discriminate between the two distinct outcomes of low back pain (LBP) and radicular symptoms. To address this gap in the literature, we conducted a secondary analysis of existing data from the Longitudinal Assessment of Imaging and Disability of the Back (LAIDBACK). The purpose of this study was to examine the association of incident lumbar MRI findings with two specific spine-related symptom outcomes: 1) incident chronic bothersome LBP, and 2) incident radicular symptoms such as pain, weakness, or sensation alterations in the lower extremity.

METHODS: The original LAIDBACK study followed 123 participants without current LBP or sciatica, administering standardized MRI assessments of the lumbar spine at baseline and at 3-year follow-up, and collecting information on participant-reported spine-related symptoms and signs every 4 months for 3 years. These analyses examined bivariable and multivariable associations between incident MRI findings and symptom outcomes (LBP and radicular symptoms) using logistic regression.

RESULTS: Three-year cumulative incidence of new MRI findings ranged between 2 and 8%, depending on the finding. Incident annular fissures were associated with incident chronic LBP, after adjustment for prior back pain and depression (adjusted odds ratio [OR] 6.6; 95% confidence interval [CI] 1.2-36.9). All participants with incident disc extrusions (OR 5.4) and nerve root impingement (OR 4.1) reported incident radicular symptoms, although associations were not statistically significant. No other incident MRI findings showed large magnitude associations with symptoms.

CONCLUSIONS: Even when applying more specific definitions for spine-related symptom outcomes, few MRI findings showed large magnitude associations with symptom outcomes. Although incident annular fissures, disc extrusions, and nerve root impingement were associated with incident symptom outcomes, the 3-year incidence of these MRI findings was extremely low, and did not explain the vast majority of incident symptom cases.

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