Throughout life discs age. This is a natural process starting in the early twenties. The rate that discs age is variable and is often dependent upon inherited factors, previous injury, labouring or heavy occupations and smoking. As a disc ages the thick outer wall (the annular fibrosis) starts to split and tear. The wall then becomes weaker and a series of events may eventually rupture it completely. This final event can be as minor as coughing or sneezing but is often related to some form of lifting accident. When the outer wall has been torn the softer nucleus pulposis can be squeezed through the tear in it.
If this occurs within part of the disc where there are no sensitive structures then little or no pain will occur except perhaps back pain. Unfortunately the rupture (or herniation) often occurs close to a nerve root, in which case the nerve root will be irritated causing pain. If this herniation occurs in the lower back, which is common, then the nerves going down the legs will be irritated. This results in the commonly known condition of sciatica. This essentially is due to the irritation of one of the nerves that go on to form the sciatic nerve. It is due to irritation of one of the tributaries that lead into the sciatic nerve.
Disc prolapses virtually always occur in discs that are ageing or degenerate. This is because there is pre-existing weakness of the wall allowing the prolapse to occur, therefore it is a disease of middle age. Rarely it does occur in young people but it is usually related to premature disc disease. It is also a rare occurence in the elderly, as they tend to have less disc material to prolapse.
The first treatment options are physical therapy be that physiotherapy, chiropractic or osteopathy. Sufferers from prolapsed inter-vertebral discs should be given adequate pain relief to allow them to mobilise and anti-inflammatories to reduce the inflammation around the nerve roots. A positive approach should be taken to rehabilitation, people should be reassured that they are not doing any harm with movement and more likely to do a great deal of good. Sufferers should be reassured that they are not masking any nasty symptoms by taking adequate pain killers as any major problem would break through any pain killers they are able to take in any event.
In the ideal world, this form of mobilisation with adequate pain control, form the first six weeks of treatment. The vast majority of people find that at the end of this six week period most of their symptoms have resolved. Those people with continuing symptoms at about the six week stage could possibly be offered investigation using an MRI scan to confirm the diagnosis followed by a form of injection such as a caudal epidural. A caudal epidural is not only used for temporary pain relief but also to instill a strong anti-inflammatory agent, hydrocortisone. The idea is to bathe the nerve root, which is presumed to be inflamed & swollen, with a strong anti inflammatory agent thereby hopefully reducing the inflammation of the nerve root as the disc prolapse continues to reduce in size. Essentially this buys the sufferer more time whilst nature takes its course. The hydrocortisone injection therefore treats not only chemical irritation of a nerve root but pain from chemical and cellular sources leaking from the prolapsed disc itself.
If this approach is unsuccessful and there is no relief of sciatica, then some form of discectomy could be offered provided there is a relevant surgical lesion. The surgical approaches depend upon the surgeon’s preference and indeed the pathology identified. The least invasive method is a percutaneous discectomy and there are a number of new technologies to allow disc material to be removed via a needle under sedation. The great advantage of this technique is the fact that it is a day case or overnight stay activity done under sedation. The reason sedation is employed is to allow accurate placement of the needle into the disc without being too close to the nerve root. If the nerve is encountered, then the patient will let the surgeon know. This technique however is not appropriate for disc fragments within the canal; a more traditional open technique is required for these.
The open techniques again vary from surgeon to surgeon and range from the use of an operating microscope to the standard mini discectomy. The actual operation is the same and there maybe some advantages in using a microscope largely in terms of illumination. The operation is designed to remove the fragment of disc from being in contact with the nerve root therefore removing the leg pain. These sorts of procedures are not intended to improve any form of backache although occasionally this can be a positive by-product. In the lumbar spine this type of surgery is done posteriorly, in other words from the back.