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Lumbar Microdiscectomy and Rhizolysis

What is a microdiscectomy?

A microdiscectomy is a minimally invasive procedure performed on the lumbar spine to remove a piece of protruding disc that is compressing a nerve root. Rhizolysis refers to decompression of the nerve root. The nerve root is the first part of the nerve that arises from the spine and after joining with other nerve roots will form a peripheral nerve that conducts messages for sensations such as pain as well as muscle movements.

What is the anatomy of the lumbar spine?

The lumbar spine consists mainly of the vertebrae or bone of the spine with a disc in between each bone. There are five lumbar vertebrae (referred to as L1-5). The main part of the vertebra is called the body and is located towards the front. The disc is located between the vertebral bodies. Each disc is referred to by the bones between which it sits. For example, the L4/5 disc is located between the L4 and L5 vertebral bodies.

Behind the vertebral bodies there is a ring of bone that contains the bottom of the spinal cord which ends at L1/2 and the nerve roots. The back of this ring is made of the lamina and spinous processes to which several muscles are attached. For most of the lumbar spine, there is a group of nerve roots which trail down from the bottom of the spinal cord. The nerve roots, which are surrounded by spinal fluid and which are enclosed in a sac called the dura, are referred to as the cauda equina which translates to ‘horse’s tail’. At each level a nerve root exits the spine through a hole between each bone called the intervertebral foramen. That nerve root will supply feeling (sensation) to an area and will also supply muscles that perform different movements.

The disc is made of two main elements. The first is the annulus fibrosis. This is a strong outer layer made of criss-crossing fibres. The inside of the disc, or nucleus pulposus, is the soft gel-like centre which normally provides the cushioning functions of the disc.

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

Radiculopathy is a clinical condition usually due to compression of a nerve root. The nerve root is the start of a nerve as it exits from the spinal cord and spinal canal. It usually will join with other nerve roots outside of the spinal canal to form various peripheral nerves. Nerve roots normally supply sensation to a particular area of the body as well as supply various muscles to make them move. Radiculopathy is most commonly painful and the area in which the patient experiences pain will often indicate the nerve involved. In addition, there is often numbness and paraesthesia. Paraesthesia is commonly referred to as pins and needles. Again, these may indicate the nerve root that is affected. Finally, there may be weakness of a muscle or of a movement.
Nerve root compression causing radiculopathy is most commonly due to a disc protrusion or bony spurs (osteophytes). There are many other reasons for radiculopathy such as a synovial cyst for example.

Cauda equina syndrome is unusual and generally occurs with large centrally located discs that compress multiple nerve roots within the spinal canal. It is a condition of multiple radiculopathies.

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
  • Surgery

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.

  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 surgery can persist, 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.

What happens prior to surgery?

Prior to surgery, patients may be asked to attend a preadmission clinic. This will involve routine blood tests and for some patients an ECG and chest X-ray. Patients that have significant co-morbidities or illness may require extra assessment.

When do I stop my blood thinning medication?

Patients who are on aspirin or clopidogrel should cease those medications 7 days before surgery. However, for this surgery, these medications may be continued in some circumstances. For patients who are on warfarin, management will depend on the original reason for their warfarin. Some patients will require early admission and be started on heparin, for example, patients with mechanical heart valves. Others will just need to stop taking warfarin 2 days before surgery. The INR will be checked before surgery.

What about other medications?

Other medications should be continued including those usually taken on the morning of surgery. These medications should be taken with a sip of water even though the patients may be nil by mouth otherwise.

How long do I need to fast prior to surgery?

All patients undergoing a general anaesthetic will need to fast. That is, they should have nothing to eat or drink for around 8 hours prior to surgery. Failure to comply with this may necessitate cancellation of the procedure as it may expose the patient to significant risk. As most patients are admitted on the day of the surgery, the hospital will contact them to inform them of the time for admission, likely time of surgery and the required fasting times on the day before the surgery.

What scans do I need to bring to hospital?

Most patients are admitted to hospital on the day of the surgery. Patients need to ensure that their latest X-rays, CT scans and MRI scans are with them when they come to hospital. These scans are the surgeon’s road map and without them the operation cannot proceed. If you do not have your pictures with you when you are admitted the operation may need to be cancelled. Except in rare circumstances, patients are responsible for these films, and are normally given back to them at the time of consultation.

How is a lumbar microdiscectomy performed?

The operation is performed under a general anaesthetic with the patient lying face down. An x-ray is performed to ensure the incision is made directly above the level of the disc protrusion. The incision is marked and the skin prepared with antimicrobial solution.

A small incision of approximately 3 cm is made and the muscle dissected off the back of the spine. While using the operating microscope, a small opening is made in the spine and the nerve root identified. It is then gently retracted to expose the disc. The disc is opened and the piece of disc that has protruded is removed along with any other loose pieces of disc material. The nerve root is checked to ensure it free. The wound is washed and a small amount of steroid is placed on the nerve root to reduce inflammation of the nerve root in the period just after the surgery. The wound is then sutured closed with dissolving sutures. The average time for the operation is one hour but it may vary depending on the patient and the pathology.

When the operation is complete the patient will be woken from the anaesthetic and taken to the recovery room. After a short period of observation, the patient is taken to the normal ward for the remainder of their hospital stay. A wound drain is not normally used but patients will have an intravenous cannula (‘a drip’) for 24 hours through which they will receive fluids and antibiotics. Occasionally patients (usually men) will have temporary trouble passing urine and will require a catheter for 24 hours but this is unusual.

Patients are normally able to stand and walk that evening and will almost always do so the next day with the physiotherapist.

What are the risks of surgery?

While a microdiscectomy is one of the safest and most common spinal operations performed, all surgery caries risk. There are risks common to all surgeries such as infection, bleeding, deep vein thrombosis (DVT), pulmonary embolism and those associated with a general anaesthetic.

The spinal cord is normally well clear of the site of the surgery. In the lower lumbar spine, the spinal cord has changed into a group of nerve roots called the cauda equina. While patients commonly worry about complications such as paraplegia and incontinence, such problems would be extremely rare. More common is the chance of injuring one nerve root at the site of the surgery and the risk of this is less than 1% and may result in numbness or weakness of the leg which may be permanent.

The most common complication is that of disc recurrence. The rate of recurrence is approximately 10% and may occur early or late. This usually results in recurrence of symptoms and may require a reoperation. The reason for recurrence is that the disc is unhealthy with or without surgery. While the protruding fragment and any other loose disc is removed, the aim is to keep as much of the disc as possible behind. Thus, after the surgery further disc material may occasionally come out of the disc space, usually through the same hole and compress the nerve.

Occasionally patients will experience persistent back pain after surgery. This occurs in about 10% of patients. It normally does resolve. It probably occurs because of the disc itself. It can sometimes be treated with further surgery but that is rare.

Persistent or recurrent pain in the leg can occur for several reasons. It may be that there is a disc recurrence as mentioned above. However, some patients will experience leg pain because of changes that occur in the nerve itself after it has been compressed severely or for an extended period. This pain, which often has a burning quality, is termed neuropathic pain. Some patients will develop scar tissue around the nerve. Some scarring is normal as it is the body's natural response to healing. However excessive scar tissue is thought to be a reason for recurrence of pain.

There are numerous other very rare complications that may also occur including those associated with a general anaesthetic such as reactions to medication, visual loss, discitis, i.e., a deep-seated infection of the disc space.

How long is the hospital stay?

The hospital stay is normally around 2 days in total but varies depending on the patient and their underlying condition. During the hospital stay the patient receives daily physiotherapy. Patients will receive prophylactic subcutaneous heparin injections and are required to wear stockings to prevent DVTs.

After surgery, there is normally some discomfort and analgesia is provided. However, the amount of analgesia required is usually small. Constipation is a common complaint after surgery and is usually due to analgesics. You should inform staff if this becomes an issue.

How do I care for the wound after surgery?

The wound is normally cleaned and the dressing changed each day. After discharge no dressing is required. You may shower and then pat the wound dry with a clean towel afterwards. While the wound may get wet, do not soak it in the bath or in a pool for at least 2 weeks after the surgery. Do not rub the wound. If there are any concerns such as excessive redness, pain or ooze then you should have your GP review the wound as the first step.

What should I do at home after surgery?

After discharge, it is advisable to rest for 2 weeks which should consist of normal daily activities. One should maintain a good posture as advised by the physiotherapists, for example, you should not slouch in a chair. You should not spend too long in any one position. Once you feel more confident then activities such as driving can resume. Normally one can drive after 2 weeks from the date of surgery. A return to work depends on the work environment. Those with sedentary jobs can usually begin to go back to work after 2-4 weeks. Those with more manual jobs should wait at least 6 weeks but it should be discussed with Prof Owler.

What are the physical restrictions after lumbar microdiscectomy?

The main physical restriction relates to lifting. For the first 2 weeks, there should be no lifting but this can be slowly increased after that period to weights <5Kg for another 4 weeks. Patients are then able to lift weights <10Kg until 3 months post-operatively. Generally, no-one should be lifting weights >20Kg even after 3 months but this needs to be balanced against the patients’ occupation and normal activities.

Patients are encouraged to walk and undertake gentle exercise from around 2 weeks after surgery. This is gradually increased after surgery depending on how the patient feels. Exercise should be non-impact for the first 3 months. Therefore, activities such as running should not be undertaken until after that time.

When do I follow-up with Prof Owler after surgery?

We will normally make an appointment for you to see Prof Owler 6 weeks from the date of surgery or thereabouts. At that visit any concerns can be discussed and the wound will be checked. If there are any significant problems, then you should contact his office earlier.

What are the expected outcomes from lumbar microdiscectomy?

Pain is the most common symptom of radiculopathy and, in most cases, is the first symptom to improve; often immediately after the surgery. Pins and needles may take longer but tend to improve quickly.

Numbness takes the longest period to recover, perhaps even over 12 months and some patients may not experience full recovery of numbness.

Weakness has variable recovery depending on severity and duration before surgery. Some patients will experience recovery immediately while others may have persistent weakness despite the surgery. Normally physiotherapy is required to treat weakness.

Overall about 90% of patients will experience significant improvement in pre-operative symptoms while a further 10% will not improve as much as is hoped and 1-2% percentage will be worse off in relation pain or some other problem. No guarantees can be given in relation to the surgery.

What on-going care do I need for my spine after surgery?

Unfortunately, discs do not heal or regain their normal integrity once they have been injured. With or without surgery the disc will remain unhealthy. This is one of the reasons why late disc recurrences occur. Therefore, it is important to care for the spine in the future.

Prof Owler’s philosophy is to attempt to return the patient to a normal active life rather than place onerous restrictions on the patient. However, there are two aspects of spinal care that are important to patients that have undergone surgery.

The first, and somewhat obvious, advice is to avoid activities that may reinjure the spine. In the simplest form this includes not lifting heavy or awkward objects. As a general rule, no-one should generally be lifting weights above 20Kg. In the short term the lifting restrictions are much less (see above). When lifting, good technique should be used such as keeping the knees bent and back straight while keeping the object being lifted close to the body.

People should avoid simultaneous lifting and twisting. Lifting and twisting is the most common mechanism of injury to lumbar discs. It is a common way to cause a recurrent disc protrusion. Those who are golf enthusiasts should wait 3 months after surgery before resuming golf.

The second aspect to long-term care is maintaining spinal fitness. This includes weight loss, core strengthening and on-going exercise. The best exercises are those which are non-impact such as swimming and cycling. All patients are normally taught core-strengthening exercises. These should be continued independently by the patient at home indefinitely.

Important Information

This information was provided to assist you. While it has been prepared to provide accurate information the practice and techniques of surgery will differ between surgeons. Likewise, the information is a generalisation in relation to the surgery and will vary between patients depending on the individual and their pathology. This information cannot cover all aspects of the surgery especially in relation to surgical risks and should not be considered an exhaustive explanation. Please contact Prof Owler’s office if there are any further concerns or questions.

  • Australian Medical Association
  • Neurosurgical Society of Australasia
  • The Sydney Children Hospitals Network
  • Sydney Adventist Hospital
  • Norwest Private Hospital
  • Royal Australasian College of Surgeons