Lumbar Disc Protrusions
What is the anatomy of the lumbar spine?
What is a disc protrusion?
When a disc becomes unhealthy, the nucleus can become shrunken and loses its normal water content. Thus, the annulus tends to bulge and, in some cases, can rupture leading to protrusion of the unhealthy nucleus into the spinal canal.
A disc protrusion may occur at any time and at any age but most commonly occurs with twisting movements of the back, especially when carrying a heavy object. Lifting and twisting is the most common mechanism of injury to result in a disc protrusion. The pain may occur straight away, or may begin the next day or even later. Pain can be incapacitating. Normally with treatment with analgesics, pain will improve over time, although improvement may take several weeks. It is important to realise that most patients will spontaneously improve over a period of weeks. Most patients will benefit from physiotherapy once pain begins to settle, but if the pain is severe, then rest and analgesia are best.
The most common site for a disc protrusion is the L4/5 disc with the L5/S1 disc being the second most common level to be affected. Within each level, a disc may be in different locations. These include centrally, posterolaterally (the most common) and far laterally. The level, location, and size of the disc protrusion will determine the clinical consequences of the disc protrusion.
What are the symptoms of a lumbar disc protrusion?
Most disc protrusions are probably asymptomatic. This means that they cause little or no clinical problems for the patient. They are often small and are frequently noted on CT or MRI scans. These asymptomatic disc bulges or protrusions need no treatment. The aim of treatment is to improve the patient’s symptoms rather than just improve the appearance of the CT/MRI scans.
Other patients will experience very significant symptoms. The most common is pain. This includes both lower back pain and leg pain. The leg pain is often called radicular pain, or more commonly, sciatica. Symptoms of lumbar disc protrusions can be classified as:
Nerve Root Compression
Discogenic Low Back Pain
Low back pain frequently occurs after a disc protrusion. In some cases, it may be the only symptom. For the vast majority of patients this will settle with conservative treatment. In a few cases, pain,will persist and surgery may be contemplated after other measures have failed. However, in those circumstances this may require a fusion procedure.
For patients that have both radicular leg pain and low back pain, the most common pattern is for the back pain to resolve and the leg pain to persist. Patients in whom both persist will most commonly be treated by a microdiscectomy. In this case, the primary aim of the surgery is to relieve nerve root compression. The expectation is that the leg or radicular pain will improve or resolve.
However, the lumbar pain may also be relieved in some cases even though the back pain is not the primary reason for surgery.
What are the treatment options for a lumbar disc protrusion?
Those patients who do not improve spontaneously may be considered for various treatments. There are three basic groups of treatments. These are:
- Conservative management
- Cortisone injections
Conservative management includes physiotherapy, chiropractic, massage, and acupuncture, etc. Most of these treatments are aimed at symptom control. Although some claim that the disc can be ‘popped’ back into position, this is not possible. Traction may reduce the bulge or protrusion temporarily but it will return when the patient is upright and weight is again placed through the disc. Discs do however shrink and in some cases, disappear over time. This is most likely due to a natural healing process.
In the initial stages, when pain is severe, bed rest and analgesia are advised. Analgesics should be prescribed by the general practitioner. It may include painkillers such as codeine and paracetamol along with anti-inflammatories. When the initial pain begins to improve, physical therapy with a focus on gentle exercise and stretching is appropriate. This will also include core-strengthening exercises. Exercises and activities are normally gradually upgraded as the pain resolves. Most patients (80-90%) will be successfully managed in this manner.
Cortisone injections are performed by a radiologist under CT guidance and involve the injection of a steroid and local anaesthetic around the nerve. The response is variable with some patients having no relief but others having long lasting relief. It may take up to 7 days to have its effect. The effects of the injection often wear off after a few months and some patients can have a second injection if required. It is a good option for those with small disc in whom the condition is expected to resolve, and where pain is the predominant symptom. It does not treat weakness or numbness.
What are the indications for surgery?
Surgery is indicated if patients fail conservative treatment after a period of 6-8 weeks, have a large disc that is unlikely to improve without treatment, or if they exhibit weakness. Weakness needs to be dealt with promptly as the longer it persists then the less the chance of recovery.
There are three main indications for surgery:
1. Failure to respond to conservative management: This is the most common category. As a general rule, patients who have persistent and significant pain after 2 months have a lower chance of improvement, and in these cases, surgery is a reasonable option. In the absence of weakness, surgery is not an imperative but if pain continues for extended periods (>6 months) then the success rate of surgery may be reduced due to neuropathic pain.
2. Weakness: As a general rule, the longer that weakness persists, the lower the chance of recovery. Weakness can be debilitating especially for very active people. In some patients, if there is evidence of continued improvement and the weakness is mild, continued conservative treatment may be appropriate although most will proceed to surgery.
3. Large disc with severe symptoms is unlikely to resolve without surgery: Even large discs can respond to conservative management. However, if a patient is in significant pain and the disc is large, it may take some time for it to resolve. Surgery may be the most rapid and effective treatment in this circumstance.
Patients with cauda equina syndrome require urgent treatment and it is treated as a neurosurgical emergency.
The type of surgery varies depending on the nature of the disc and other factors, but by far the most common treatment is that of lumbar microdiscectomy. There is more information under that section on this website. However, in certain circumstances other procedures such as a fusion may be the most appropriate form of surgery.
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