Disc Herniation: When the MRI Matches and When It Doesn't

"My MRI showed a disc herniation." It's one of the most common opening lines we hear in a back-pain consultation. It's also, in isolation, one of the least useful pieces of information for deciding what to do next. The disagreement between MRI findings and clinical pictures is one of the most studied — and consistently surprising — areas in spine medicine.

This isn't an argument against imaging. It's an argument for matching the imaging finding to the clinical exam, not the other way around.

How common are disc findings in people without pain?

Brinjikji and colleagues' systematic review pooled 33 studies of MRI findings in asymptomatic adults. The results are striking: disc degeneration was present in 37% of 20-year-olds with no back pain, climbing to 96% by age 80. Disc bulges were present in 30% of asymptomatic 20-year-olds and 84% of asymptomatic 80-year-olds. Disc protrusion was present in 29% of pain-free 20-year-olds¹.

Translation: a disc bulge or protrusion on MRI in someone with back pain may be related to the pain, or may simply be one of the many findings that would have appeared if you'd scanned them ten years ago when they had no symptoms at all. The imaging alone can't tell you which one.

When imaging genuinely changes the plan

There's a relatively short list of clinical scenarios where MRI changes management. They include:

• Suspected serious pathology — cauda equina syndrome, tumor, infection, fracture — where red flags are present on history and exam.
• Progressive or severe neurologic deficit — measurable, progressing weakness or sensory loss in a clear nerve root distribution.
• Radicular pain that has failed appropriate conservative care over an adequate timeframe (typically 6–12 weeks) and is being considered for injection or surgical referral.

For mechanical low back pain without these features, current clinical guidelines from the American College of Physicians, NICE, and the global consensus reflected in the Lancet low back pain series all recommend against routine imaging^2,3. The reason is straightforward: imaging produces findings that don't change non-surgical management and can prompt unnecessary intervention.

The clinical exam still does most of the work

For a true symptomatic radiculopathy — a disc herniation actively irritating a nerve root — the clinical exam is usually clear. Pain follows a recognizable dermatomal pattern, neurologic findings are present and concordant, and provocation tests reproduce the radicular symptom. In that picture, an MRI confirms what the exam already strongly suggested, and the imaging can be useful for planning if symptoms haven't responded to conservative care.

This is the framing we use in our piece on sciatica — the diagnostic conversation matters because it changes the plan. A back ache with non-radicular symptoms and a "disc bulge" on MRI is a fundamentally different clinical picture than a true L5 or S1 radiculopathy, even if the imaging language sounds similar.

Why "I have a disc bulge" can be a problem all by itself

There's a small but consistent literature on the harm of imaging language. People who are told they have a "torn," "degenerated," or "bulging" disc tend to report higher pain intensity, more disability, and more avoidance behavior than people with similar clinical presentations who weren't given that language⁴. Not because the imaging is wrong, but because the words the patient hears shape what they believe about their back.

One of the more useful things a clinician can do for a patient with a recent MRI is contextualize it: yes, that's there; here's how often we see that in people without symptoms; here's what your exam actually shows; here's what changes our plan and what doesn't.

What we do at Boreal

For most patients with mechanical low back pain, the first visit at Boreal Spine & Sport doesn't include or require an MRI. We work from a careful history, a neurologic and orthopedic exam, and a movement assessment. If the picture warrants imaging, we say so, and we coordinate with the referring physician. If it doesn't, we don't introduce a layer of investigation that's unlikely to change the plan.

This isn't about avoiding imaging. It's about using it the way the evidence suggests it should be used — when the result will actually change what happens next.

References

1. Brinjikji W, Luetmer PH, Comstock B, et al. Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. AJNR Am J Neuroradiol. 2015;36(4):811–816.
2. Qaseem A, Wilt TJ, McLean RM, Forciea MA. Noninvasive treatments for acute, subacute, and chronic low back pain: a clinical practice guideline from the American College of Physicians. Ann Intern Med. 2017;166(7):514–530.
3. Foster NE, Anema JR, Cherkin D, et al. Prevention and treatment of low back pain: evidence, challenges, and promising directions. Lancet. 2018;391(10137):2368–2383.
4. Sloan TJ, Walsh DA. Explanatory and diagnostic labels and perceived prognosis in chronic low back pain. Spine (Phila Pa 1976). 2010;35(21):E1120–E1125.

Author: Dr. Michael Minenna D.C., B.Sc., SFMA, FMS — Boreal Spine & Sport, Winnipeg, Manitoba.