Degenerative disc disease

Degenerative disc disease is a name for changes in the spinal discs seen on X-rays or MRI scans: discs that have lost water and height, often with bulges or small splits in their outer ring. Despite the word “disease”, it mostly describes how discs age. A review of 3,110 people without any back pain found disc degeneration in 37% of 20-year-olds and 96% of 80-year-olds (Brinjikji et al., 2015). In the neck, the NHS calls the same process cervical spondylosis, “a normal part of ageing”, and notes that many people have no symptoms (NHS).

What happens to a disc as it ages?

Each intervertebral disc has a gel-like centre, the nucleus pulposus, inside a tough ring, the annulus fibrosus. With age, the nucleus dries out and loses some of the molecules that hold water, so the disc absorbs shock less well and loses height, which is part of why people get a little shorter as they grow older. The ring weakens and is more likely to tear, the cartilage endplates thin, and small fissures form (Kenhub).

A thinner disc changes its neighbours too: a ligament inside the spinal canal, the small facet joints at the back of the spine, also called zygapophyseal joints, and the openings where nerves leave. In older people, this is the main cause of spinal narrowing and of nerve pain linked with disc degeneration (Raj, 2008).

Does degenerative disc disease cause pain?

Sometimes, but a scan alone can’t tell. The 2015 review concluded that many such imaging features are likely part of normal ageing and unrelated to pain, and must be read alongside a person’s symptoms (Brinjikji et al., 2015).

They are not meaningless either. A second meta-analysis of 3,097 adults aged 50 or younger found that disc degeneration, bulging discs, protrusions and extrusions were more common in people with back pain than without (Brinjikji et al., 2015). In younger adults these findings go with back pain on average, even though plenty of people without pain have them too.

Is it caused by sitting or heavy work?

The Twin Spine Study, which compared twins with very different working and leisure lives, found that heredity has a substantial influence on lumbar disc degeneration. Despite large differences between twins in physical loading over adulthood, the effect on their discs was surprisingly small. Smoking had a small effect, driving and vehicle vibration showed no clear acceleration, and there were some signs that routine loading may even benefit the disc. The authors concluded that the old “wear and tear” model was not supported (Battié et al., 2009).

Those studies compared heavier and lighter physical work rather than desk sitting, but they undercut the idea that daily use simply grinds discs down. For neck changes, the NHS adds a previous neck injury and a family history as risk factors (NHS).

What does the diagnosis mean for treatment?

Mostly the same as for other back and neck pain. NICE advises against routine imaging for low back pain outside specialist settings, and recommends self-management advice, carrying on with normal activities and considering a group exercise programme (NICE). For neck symptoms, the NHS suggests gentle neck exercises, keeping up usual activities and physiotherapy if things don’t improve within a few weeks (NHS). See lower back pain from sitting and Is walking good for back pain?

When to see a doctor

For the neck, see a GP if pain or stiffness hasn’t gone after a few weeks. Get an urgent appointment or call 111 for severe neck pain that starts suddenly, heaviness or weakness in the arms or legs, pins and needles in an arm with neck or arm pain, or pain between the shoulder blades. Call 999 for new problems walking, loss of bladder or bowel control or sudden clumsiness (NHS). For the lower back, call 999 for pain, tingling or weakness in both legs or changes in bladder or bowel control (NHS).