Disc Herniations: What Does a Disc Bulge Actually Mean?
Being told you have a disc bulge, disc protrusion or disc herniation can sound frightening.
It's easy to picture a disc being "out of place", your spine being damaged, or something that needs to be pushed back in.
Fortunately, the reality is usually much less alarming.
Disc changes are incredibly common, and importantly, a disc herniation on an MRI does not automatically mean it is the cause of your pain.
So what actually is a disc herniation, when does it matter, and why can two people with similar MRI findings experience completely different symptoms?
What Is a Disc Herniation?
Between the vertebrae of your spine sit structures called intervertebral discs.
These discs help distribute load and allow movement through the spine. They have a tougher outer portion, known as the annulus fibrosus, surrounding a softer centre called the nucleus pulposus.
The term disc herniation describes displacement of disc material beyond its usual boundaries.
Depending on its appearance, an MRI report might use terminology such as:
Disc bulge
Disc protrusion
Disc extrusion
Disc degeneration
Annular fissure
These terms describe what the spine looks like on imaging. They don't necessarily tell us how much pain somebody should be experiencing.
Can You Have a Disc Herniation Without Pain?
Yes.
This is one of the most important things to understand about spinal imaging.
A well-known systematic review by Brinjikji et al. (2015) examined imaging findings in 3,110 people without back pain.
The researchers found that disc-related changes were surprisingly common in people who had no symptoms at all.
For example, the estimated prevalence of a disc protrusion in people without back pain was:
29% at age 20
31% at age 30
33% at age 40
36% at age 50
38% at age 60
40% at age 70
43% at age 80
Disc bulges were even more common, increasing from approximately 30% of asymptomatic 20-year-olds to 84% of asymptomatic 80-year-olds.
In other words, if we MRI enough people who don't have back pain, we will still find plenty of disc bulges, protrusions and other changes.
This is why an MRI finding should always be interpreted alongside someone's symptoms and clinical examination rather than being viewed in isolation.
Does That Mean Disc Herniations Don't Cause Pain?
No, and this distinction is important.
The fact that disc changes can exist without symptoms doesn't mean they're never relevant.
A separate systematic review and meta-analysis by Brinjikji et al. (2015) compared MRI findings in people aged 50 and under with and without low back pain.
Disc bulges, protrusions, extrusions and degeneration were all more prevalent among people experiencing low back pain.
So the message isn't:
"Disc herniations don't cause pain."
It's:
"A disc herniation can be relevant to someone's pain, but its presence on an MRI alone doesn't prove that it is the cause."
The clinical picture matters.
Disc Herniation With Back Pain
A disc-related presentation doesn't necessarily involve a nerve.
For some people, symptoms may predominantly involve lower back pain, sometimes with discomfort around the buttock or hip region.
There may be pain with certain movements, positions or activities without significant neurological symptoms travelling down the leg.
This is an important distinction because people often assume that any disc herniation automatically means "sciatica".
It doesn't.
Disc Herniation With Nerve Pain
A disc herniation can become more clinically significant when it affects or irritates a nearby spinal nerve root.
This can produce radicular pain, commonly described as pain travelling from the lower back or buttock into the leg.
Depending on the nerve involved, someone may experience:
Shooting or electric pain into the leg
Burning pain
Pins and needles
Numbness
Changes in sensation
Muscle weakness
Changes in reflexes
People often call any pain travelling into the leg "sciatica", although true radicular symptoms generally involve irritation or compromise of a nerve root.
This is where assessing someone clinically becomes particularly important.
A scan can show us the structure of the spine, but an examination can help establish whether the imaging findings actually correspond with the person's symptoms and neurological findings.
Why MRI Results Need Context
Imagine two people undergo an MRI.
Both scans show an L5/S1 disc protrusion.
Person A has no back pain, no leg symptoms and no neurological changes.
Person B has lower back pain, pain travelling down the leg in a pattern consistent with a particular nerve root, altered sensation and weakness that also correspond with that nerve.
The words on their MRI reports might look similar, but the clinical relevance of those findings could be very different.
This is why we don't treat an MRI.
We treat the person in front of us.
Imaging is one piece of the puzzle.
Do You Always Need an MRI for Back Pain?
No.
For many episodes of uncomplicated lower back pain, imaging isn't immediately required.
An assessment will consider your symptoms, how they started, what makes them better or worse, your neurological function and whether there are any features that warrant further investigation.
Imaging may become more relevant in certain circumstances, particularly when there are significant or progressive neurological symptoms, concerning clinical features, or when the results are likely to change management.
Can a Disc Herniation Heal?
Disc herniations aren't necessarily permanent.
Symptoms can improve significantly over time, and having a previous disc herniation doesn't automatically mean you'll always have a "bad back".
Recovery may involve gradually returning to movement, exercise and normal activity while managing symptoms appropriately.
Depending on the presentation, rehabilitation may include:
Gradually increasing general movement and activity
Strengthening the trunk and lower body
Building tolerance to bending and lifting
Returning progressively to gym training or sport
Modifying aggravating activities temporarily
Gradually restoring confidence in movement
The exact approach will depend on the individual, particularly when nerve symptoms or neurological changes are present.
Your Spine Is Not Defined by Your MRI
Perhaps the most important message is that structural changes on an MRI don't provide a complete explanation of someone's pain.
Brinjikji and colleagues demonstrated that disc bulges, protrusions and degenerative changes can be found in a substantial number of people who are completely pain-free.
That doesn't mean MRI findings should be ignored.
It means they need to be interpreted appropriately.
If your MRI says you have a "disc bulge", "degenerative disc disease" or "disc protrusion", don't assume this means your spine is damaged or that you need to avoid movement indefinitely.
The important questions are:
Does the finding correspond with your symptoms?
Are there signs of nerve involvement?
And what can we do to help you return to the activities you want to do?
When Should You Get Back Pain Assessed?
If you're experiencing persistent lower back pain, pain travelling into your leg, numbness, pins and needles or weakness, a clinical assessment can help determine whether nerve involvement may be contributing to your symptoms.
At Dunmore Osteopathy in Chatswood, I assess and manage people with lower back pain, including presentations involving disc-related pain and nerve symptoms.
Treatment and rehabilitation are individualised around your symptoms, examination findings and goals, with the aim of helping you understand what's happening and gradually return to normal activity.
References
Brinjikji W, Luetmer PH, Comstock B, et al. (2015). Systematic Literature Review of Imaging Features of Spinal Degeneration in Asymptomatic Populations. American Journal of Neuroradiology, 36(4), 811-816.
Brinjikji W, Diehn FE, Jarvik JG, et al. (2015). MRI Findings of Disc Degeneration are More Prevalent in Adults with Low Back Pain than in Asymptomatic Controls: A Systematic Review and Meta-Analysis. American Journal of Neuroradiology, 36(12), 2394-2399.
Comments