Cervical and lumbar degenerative disc disease: what it is, when it hurts and how it is treated

What degenerative disc disease is

Between one vertebra and the next lies a disc that acts as a shock absorber: at its centre is the nucleus pulposus, a water-rich gel, surrounded by theannulus fibrosus, made of layers of criss-crossing fibres. Over time the disc can lose water and height, and the annulus may develop small tears.

Studies distinguish normal ageing of the disc from true degeneration, i.e. a failure of the disc structure (tears, herniations, endplate lesions) to which the disc cells respond abnormally. The term degenerative disc disease is used only when the degenerated disc is also painful [2]. The terms in the report also have precise meanings: a bulge (bulging) is a broad, uniform extension of the disc beyond its margins, whereas protrusion and extrusion indicate a true herniation [15].

Why the disc degenerates

For decades, disc degeneration was considered mainly the result of “wear and tear” and heavy work. Twin studies changed this view: disc degeneration depends largely onheredity, while differences in physical load at work and in leisure time showed a surprisingly small effect. Smoking increases degeneration, but only modestly; body weight and muscle strength matter more than workload, and normal daily loading may even be good for the disc [3].

Recognised causes therefore include genetic predisposition, age, the limited nutrition of the disc (which has few blood vessels) and loading history, which together can weaken the disc until it fails even during everyday activities [2]. An adult disc has limited capacity for repair: this is why the aim of treatment is to make the person feel well, not to “rejuvenate” the disc.

Symptoms: back and neck

Lumbar degenerative disc disease. The most common symptom is back pain that varies with posture and load, often coming and going. If the degenerated disc is accompanied by aherniated disc or a narrowing of the canal (lumbar stenosis), pain may run down the leg with tingling or loss of strength. When the disc loses a lot of height, it can also contribute to the slipping of a vertebra (spondylolisthesis).

Cervical degenerative disc disease. It causes neck pain and stiffness. If the disc, a herniation or osteophytes (bone spurs) compress a nerve root, the pain radiates to the arm: this is cervicobrachialgia. If the compression involves the spinal cord, it is called cervical myelopathy: clumsy hands, difficulty with fine movements, unsteady gait. It is a condition that must be assessed without delay [10].

When to see a doctor straight away

Some signs require urgent assessment, because they may indicate severe nerve compression or a cause other than disc degeneration [14]:

• worsening loss of strength in the legs or arms;
• difficulty passing urine, loss of bladder or bowel control, numbness in the genital area and inner thighs;
• fever, unexplained weight loss or a history of cancer;
• pain after a significant injury, or in cases of known osteoporosis;
• clumsy hands and an unsteady gait that appear or get worse.

How it is diagnosed

Diagnosis starts with the clinical examination: the history of the pain and the assessment of strength, reflexes and sensation. Magnetic resonance imaging (MRI) shows the condition of the discs: a healthy disc is bright on T2 sequences because it is rich in water, while a degenerated disc becomes darker and lower. Radiologists classify it into five grades (Pfirrmann classification), with good agreement between different observers [4].

Reports often mention Modic changes, changes in the bone next to the disc described in three types [6]. They are present in a median of 43% of people with low back pain or sciatica compared with 6% of the general population [5]; in people up to the age of 50, type 1 is associated with back pain more than the other types [7].

The key point is that dark discs, bulges and small protrusions are very common even in people who feel well, and become more frequent with age [1]. Under the age of 50 they are slightly more common in people with back pain [7], but on their own they do not explain the pain. An MRI must always be read together with the symptoms and the clinical examination.

Treatment without surgery

For chronic low back pain, the American College of Physicians guidelines recommend starting with non-drug treatments: therapeutic exercise, multidisciplinary rehabilitation, motor control exercises, cognitive behavioural therapy, relaxation techniques and mindfulness, yoga or tai chi, acupuncture or spinal manipulation. If these are not enough, anti-inflammatory drugs are considered as the first choice [8].

​Exercise is the treatment with the strongest evidence: a Cochrane review of 249 studies concludes that it reduces pain to a clinically important degree compared with no treatment or usual care [9]. This is why the conservative pathway is built with the Ortho-Next physiotherapists, through a personalised, progressive programme. In the acute phase, when pain radiates to the leg or arm, injections may also be considered in selected cases.

When surgery is considered

If there is only back pain, without nerve compression, surgery is not the first option. Three randomised studies compared lumbar spinal fusion (arthrodesis) with intensive rehabilitation based on exercise and a cognitive behavioural approach: at one to two years the results were similar or showed only a minimal difference [11] [12], and after an average of 11 years there was no difference at all [13].

Surgery is considered instead when degenerative disc disease is accompanied by nerve compression with significant symptoms or deficits, cervical myelopathy, vertebral slippage or deformity, always after a clinical examination and with scans that match the symptoms. Depending on the case, the techniques are:

• ​ microdiscectomy or biportal spinal endoscopy, to free the nerve root from a herniation;
• decompression of the canal in lumbar stenosis;
• ​lumbar spinal fusion (arthrodesis) (TLIF, XLIF, ALIF), when the segment needs to be fused;
• ​anterior cervical spinal fusion (arthrodesis) (ACDF), for a compressed nerve root or spinal cord in the neck.

The decision is always made together with the patient: we do not operate on an image; we treat a person.

Living with degenerative disc disease

Degenerative disc disease on an MRI does not mean having a fragile back. Staying active, walking every day, keeping the trunk muscles strong and maintaining a healthy weight, not smoking and taking frequent breaks when sitting for long periods all help to control symptoms. Daily movement does not damage the disc [3] [11].