Are disc changes on an MRI normal?

What a large review found

A frequently cited systematic review in the American Journal of Neuroradiology (Brinjikji and colleagues, 2015) pooled 33 studies covering 3,110 people with no back pain. Their scans, done with CT or MRI, were reviewed for common degenerative findings, and the authors worked out how often each one appeared at ages 20, 30, 40 and so on up to 80.

The figures rose with age:

• Disc degeneration, a drying and wearing of the disc, was seen in 37% of 20-year-olds and 96% of 80-year-olds.
• Disc bulge was seen in 30% of 20-year-olds and 84% of 80-year-olds.
• Disc protrusion, where part of the disc pushes out further, was seen in 29% of 20-year-olds and 43% of 80-year-olds.
• Annular fissure, a small tear in the disc's tough outer layer, was seen in 19% of 20-year-olds and 29% of 80-year-olds.

The authors concluded that many of these imaging features are likely part of normal aging and unassociated with pain, and that they must be interpreted in the context of the person's clinical condition. They also noted that more than half of the pain-free people aged 30 to 39 had disc degeneration, disc height loss or bulging.

Where the evidence is less clear-cut

Studies disagree on how much to read into these findings. The same lead author published a second paper later in 2015, a meta-analysis of 14 studies of adults aged 50 or younger. It found that disc bulge, disc degeneration, disc protrusion, disc extrusion and some other findings were more common in people with low back pain than in people without it. For example, disc degeneration appeared in about 34% of the pain-free adults and about 57% of those with pain. The authors pointed out that the results varied a lot between studies and applied only to adults 50 and younger.

The two papers can both be true. A finding can be more common in people with pain and still be present in many people without it, so on its own it says little about the cause of one person's pain. The second paper's authors also note that earlier studies found degenerative findings in a large share of both symptomatic and symptom-free people, which limits their diagnostic value.

What this means for reading a report

Words such as degeneration, bulge or bone spur in a radiology report can sound alarming. The reviews above suggest they often describe age-related changes that are common in people without pain. NIAMS makes a related point about narrowing in the spine: it states that imaging alone will not determine whether spinal stenosis requires treatment. A British Journal of General Practice review on neck nerve problems also cautions that findings must be matched to the clinical picture to avoid overdiagnosis.

That is why a clinician usually starts with your symptoms and an examination. Whether a scan is needed at all is the topic of Do I need an MRI or X-ray for back pain? Disc findings that matter, such as a disc pressing on a nerve, are explained in What is a slipped disc? and the narrowing pattern in What is spinal stenosis?

When to get help

A report that mentions disc changes is a reason to talk it through with the clinician who requested the scan, not a reason to worry on its own. Back or neck pain with new numbness, tingling or weakness, or pain that is getting worse or not improving over a few weeks, should be assessed. The NHS says to call 999 or go to A&E (use your local emergency number elsewhere) for back pain with numbness around the bottom or genitals, being unable to pee, losing feeling in one or both legs, loss of bladder or bowel control, or pain that began after a serious accident. Practice varies by country and by clinician. See also the broader topic Discs and nerves.