It is one of the most alarming phrases a patient can read on a scan report, and one of the most common findings in people with no symptoms at all.
Has your spinal MRI reported degenerative disc disease? Many of the patients I meet find that phrase genuinely alarming, and I can see why. It sounds progressive and serious. Let me explain what it actually describes, whether “disease” is the right word, and when it truly matters.
A quick tour of the spine
Your spine is a stack of bones, divided into regions: the cervical spine at the neck, the thoracic spine in the middle of the back braced by the rib cage, the lumbar spine in the lower back, and the sacral region encased within the pelvis.
Each bone, a vertebra, is a cylindrical block with an arch of bone at the back, creating a tunnel through which the spinal cord and nerves run. Between each bone sits a disc, the cushion that absorbs shock.
What a disc is made of
Slice across a disc and look up at it from underneath, and you find two components:
- The nucleus at the centre. Its consistency when we operate on it is much like crab meat.
- The annulus, layer upon layer of lining wrapped around it, rather like interwoven fabric holding that lump of crab meat in place.
When you are upright, the load you bear is distributed evenly through the nucleus, spreading fairly equally across the segment.
The five grades
Radiologists grade disc degeneration from one to five based on MRI appearance.
Grade 1 is a normal disc. The nucleus appears bright because of its high water content, surrounded by the dark annulus.
Grade 2. With age, it is entirely normal to lose some water content. The brightness in the middle is still visible but less obvious, and the annulus appears somewhat thickened.
Grade 3, moderate. The central brightness is nearly gone, just about visible with blurred edges, perhaps with slight loss of height between the two bones.
Grade 4, severe. The whole disc has darkened, with further loss of height.
Grade 5. The disc space has fully collapsed, often with changes visible in the end plates of the vertebrae either side. At this stage you may effectively have bone rubbing on bone, which is what produces inflammatory changes.
Remember, though, that this grading is based purely on MRI appearance.
And here is the interesting part
One paper scanned people across different age groups who had no back pain and no spinal symptoms at all.
Among those aged 50 and above, 80% showed some form of disc degeneration: signal loss within the disc, darkening, loss of height, even bulging or protrusion.
A great many people have these findings and no symptoms whatsoever.
A more useful way to think about it
Far more accurate than the MRI grades are the clinical stages of disc problems.
Stage one: thinning and tearing. The lining of the disc wears thin and may tear. In the acute setting this can be painful, as inflammatory fluid from within the disc leaks out and stings the surrounding tissues.
Stage two: intermediate instability. Once the lining is torn, disc material can potentially leak out. Not always, but the disc becomes somewhat unstable, so certain sitting positions feel worse and cause more pain. This is often why sitting is more painful than walking shortly after you have torn a disc lining. If material does leak out and pinches a nerve, you get leg pain.
Stage three: stabilisation. The lining of the disc is made of collagen, which happens to be precisely what scar tissue is made of. So your body lays down collagen fibres and repairs the lining. On MRI at this stage things often look darker than normal, because water content has already been lost.
And what does that lost water content actually mean? Simply that the nucleus is not quite as squishy as it once was. Given that your spine comprises many segments, a little dehydration in one, two or even three discs will not meaningfully affect your function.
When it does matter
At grade five, where the disc has fully collapsed and there are inflammatory changes visible in the bone, that can sometimes genuinely be the source of back pain. But there are very specific tests we must do to prove it before intervening with anything invasive.
In practice, once I have excluded anything concerning on the MRI, such as nerve compression, I usually set the degenerative findings aside altogether. Treatment then becomes about restoring your normal function, tailored to your particular needs.
How I prefer to treat it
I favour a form of physiotherapy known as cognitive functional therapy. This examines the way you move, identifies any mistaken beliefs that may be driving the pain, corrects those, and restores normal functional movement so you can return to what you enjoy doing.
Core strengthening exercises can help build a muscular brace that stabilises the segment, but I think they are rather overplayed. This is not a one-size-fits-all matter, which is exactly why I believe in tailoring treatment to what you specifically need and want to be able to do.
The key takeaway
If you have back pain and your MRI describes disc degeneration, we must be careful before concluding it is the cause, precisely because the finding is so common in people without pain.
As I always say: we treat the patient, not the test result.
