Discs in the spine ('inteverterbral discs') sit between each vertebra as shock absorbers for the spine. Discs contain soft tissue in the centre of the disc ('nucleus pulposus') and an outer membrane (‘anulus fibrosis’) that surrounds the nucleus. A disc prolapse is where a tear occurs in the outer membrane, and material from the disc centre bulges outwards or 'ruptures'. This can bulge into the spinal canal, putting pressure on the spinal cord and/or spinal nerves. Disc prolapse is also described as 'herniated disc', or more colloquially 'slipped disc' (a slightly misleading term, as a disc cannot simply 'slip' in or out of place). A disc prolapse can occur suddenly or can develop over a period of weeks or months, and is much more common in adults than in children. They are also more common in the lower back (lumbar region) and the neck (cervical region), than in the mid-back (thoracic region) of the spine.
A disc prolapse is generally caused by one of two things - either a tear in the 'anulus fibrosus', or degeneration due to age or disease. Tears are often caused by heavy lifting or straining (especially when leaning forward to lift a heavy object), but can also be caused by other accidents, such as a fall from a height. When the anulus fibrosus is ruptured, not only does it allow the softer tissue inside to bulge (as described above), it can also cause the release of chemicals which themselves may cause inflammation and pain.
The primary symptom of a disc prolapse is pain in the area, however other symptoms may be present, such as…
- Tingling, numbness sensation or weakness in one or both arms or legs (or pain up and down arms / legs).
- Pain in the buttocks (with lumbar disc herniation).
- Pain in the area of the shoulder blades (with cervical disc herniation).
- Bladder / bowel incontinence (in severe prolapse).
- Numbing of genital region / impotence in men (in severe prolapse).
Tests / Diagnosis
The first part of diagnosis is determining what symptoms are present - for example any issues with walking or going to the toilet (urination or defecation) may indicate pressure on a section of the spinal cord, which may require emergency investigation and treatment. Diagnosis is normally confirmed with a CT (computed tomography) scan or a more accurate MRI (magnetic resonance imaging) scan. Occasionally, another test that may be required is CT myelography.