ANATOMY

Lumbar backache and leg pain due to lumbar disc disease is one of the most common problems that modern man is affected with. In a person's life at one stage or another one will suffer from either backache or leg pain due to this condition.

The spine consists of vertebrae which are connected to each other by the soft lumbar disc between the vertebrae

The disc is contained within a strong bag, the annulus under very high pressure

This disc has the consistency of cooked crayfish and is contained in a bag under very high pressure. Therefore should this bag rupture part of this disc will prolapse out and compress the nerve that runs down into the leg (sciatic nerve) resulting in pain. On the other hand the disc can also degenerate without causing leg pain but eventually resulting in severe backache. These two conditions although arising from basically the same underlying pathology are different aspects, needing different treatment and may run different courses

CLINICAL PRESENTATION OF THE PATIENT

.The typical clinical syndrome of a ruptured disc would be someone who develops backache as the disc bulges and stretches its containing bag. The disc then ruptures compressing the nerve and the pain then shifts and runs down the leg, often with the backache getting better. If this compression of the nerve is very severe, the nerve may become paralyzed and at this juncture the leg pain may disappear but the motor function of the nerve is now lost and the patient may present with a paralysis in the leg or in the foot, paradoxically thinking he is better.

Whereas most of these ruptured discs present with pain and mild weakness in the leg, there are situations where the consequences are much more severe requiring emergency intervention.

This may happen when the disc ruptures in the centre part of the spinal canal compressing the lower spinal cord which then may result in paralysis of both legs with loss of sensation and very importantly also loss of bladder function

The lumbar spinal cord and nerves crossing the discs

It is surprising how often a situation like this may be either misinterpreted by the patient or even by doctors and symptomatic treatment continues without realizing the significance of what has happened. If urgent surgery is not performed the patient may not regain function under these circumstances.

In the more usual case the patient presents with pain, rather than a paralysis, and/or a mild weakness. However, even in situations where the back and leg pain is very severe, the vast majority of patients will improve over a week or 10 days, never even getting to a specialist and just being treated symptomatically by their general practitioner. Patients get better because the ruptured disc will shrink somewhat and the inflammation in the compressed nerve will settle down and thereby improve the symptoms of the patient. That small group of patients who will not settle down or in whom the initial pain is so severe that they cannot live with it or when there is paralysis, will eventually land up with the neurosurgeon and at this stage further tests will be performed.

It is very important even if the problem looks like a clear-cut prolapsed disc, that a good clinical examination be performed because there are other conditions which may simulate a lumbar disc. In the younger person this will be the most likely cause. In the older person one will think more in terms of degenerative spinal disease (osteoarthritis) or even metastatic spread of cancer from somewhere else. Other conditions such as tumors in the spinal canal, hip pain or blocked arteries of the legs, must also be considered as conditions which may cause pain in the leg.

Once a full clinical examination has been performed the neurosurgeon will usually have a good idea of what he is dealing with.

SPECIAL INVESTIGATIONS- MR SCAN

At this stage then a magnetic resonance scan will be performed.

It is very important that when someone is sent for a scan that a preliminary diagnosis be made otherwise the scan may be misleading and conditions may be identified which are not appropriate in the setting of the patient's symptoms (complaints). The MR scan can usually show the problem very clearly and appropriate treatment can be advised.

The MR scan shows a huge disc prolapsed (black round object) compressing the spinal nerves in the spinal canal

Before surgery is performed it is very important to make it clear to the patient the implications and long term prognosis of a lumbar ruptured disc.

In the first instance it must be made clear that when one operates on this disc, one does not give the patient a new back and that this is part of the natural degeneration of the spine with a significant chance that there may be a recurrent disc rupture at the same level or that the disc may further degenerate, resulting in severe backache. Often one hears in conversation that people are advised not to have surgery because once you have had surgery, the back will never recover.

Secondly one must also make sure that before one embarks on surgery, all other avenues of conservative treatment have been exhausted and that the patient is not likely to recover from his pain.

Thirdly, clearly if the patient has got significant paralysis or bladder function involvement, there is no question that surgery must be performed to decompress the compressed nerve roots as a matter or urgency

SURGICAL TREATMENT

The purpose of the surgery is to remove the ruptured disc and as such remove the compression of the nerve or spinal cord so as to relieve the pain and restore the function to the nerves.

In the usual case of someone presenting with leg pain for the first time due to a ruptured disc, a procedure called a microdiscectomy will be performed. This entails making a small 3 cm cut on the back and then using the operating microscope, the dissection is carried down to the vertebra where a small hole is made in the bone and this piece of disc material removed and the nerve freed from compression.

A large piece of prolapsed disc being removed, compressing the nerve

The patient will usually be in hospital for 2-3 days and in most cases of an office job, return to work at 2-4 weeks.

However, as stated before, this hole in the bag through which the disc ruptured never properly heals and therefore there is always a chance of a disc recurrence at that level. The disc will also further degenerate resulting in complete collapse of the disc space and subsequent backache. These situations may occur in about 15% of individuals and they will require further procedures to deal with the problems

If a patient presents with a second disc rupture his chances are even higher to have a third recurrence. Therefore at this stage a supplemental procedure must be performed. In the past following the removal of the recurrent disc, a spinal fusion of that level would have been performed routinely.

However, spinal fusions also carry their own risks, especially in younger people, of increased deterioration of the adjacent disc.

Spinal fusion of the lumbar spine with instrumentation

NEW DEVELOPMENTS IN THE MODERN ERA

In the modern era, artificial disc replacement has become a major addition to the surgical options. The artificial disc will be placed in the disc space through an abdominal incision, as one has to place this in front of the spinal cord and cannot get there from behind. The artificial disc then maintains mobility in the spine and as such protects the adjacent disc from accelerated degeneration and further surgery.

Artificial disc prosthesis implanted at the L4/5 lumbar level

SPINAL DEGENERATION AND STENOSIS

As stated before one must realize that the spine ages with the individual and will not remain in a pristine state compared to a young person. Some people are more prone to developing spinal problems and in older age, backache due to spinal degeneration or narrowing (spinal stenosis) causing spinal cord compression, are the more usual conditions to deal with.

Unfortunately often in chronic backache the degeneration is widespread and no specific procedure can be performed to relieve that. These patients can then find relief from medication , physiotherapy, biokinetics , epidural dural injections and facet blocks.

In the condition where spinal stenosis develops with severe spinal cord compression, the MR scan will show the typical picture with compression of the spinal nerves.

The MR scan shows the defect in the white column which is the compression of the spinal nerves in the canal

A so called laminectomy, where the narrowing is relieved by removing the laminae (the roof) of the spinal canal is performed .This is sometimes one of the most satisfying procedures that we perform in older people. They often cannot walk more than 20 meters and they have to stop and rest before they can carry on. The dramatic relief following a laminectomy is most satisfying to the patient

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