Lumbar Microdiscectomy

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What is intervertebral disc degeneration?

Intervertebral discs are soft cushion-like structures which sit between each bone (vertebrae) in the spine. They act as shock absorbers as well as allowing normal movement between the bones in your lower back.

Each disc has a strong outer ring of fibres (annulus fibrosis), and a soft jelly-like central portion (nucleus pulposis). The annulus is the toughest part of the disc, and connects each vertebral bone. The soft and juicy nucleus of the disc serves as the main shock absorber.

In degenerative disc disease the discs or cushion pads between your vertebrae shrink, causing wearing of the disc, which may lead to herniation. You may also have osteoarthritic areas in your spine. This degeneration and osteoarthritis can cause back pain. Pain, numbness, tingling and weakness in the legs may result from pressure on the spinal nerves.

What is a lumbar disc prolapse?

A disc prolapse (herniation) refers to either a rupture or bulge of an intervertebral disc.

The intervertebral discs are soft structures which act as shock absorbers between each of the vertebrae (bones) in the spine. A single disc sits between each vertebra. Each intervertebral disc has a strong outer ring of fibres (‘annulus’), and a soft, jelly-like centre (nucleus).

A herniated disc (also known as a "ruptured" or "slipped" disc) usually occurs when part of the disc nucleus pops out of place and bulges into the spinal canal, sometimes exerting pressure on the spinal nerves. Chemicals which incite inflammation are also released from the ruptured disc, and these also contribute to nerve irritation.

Herniated discs occur most commonly in young and middle-aged adults.

Around 90% of lumbar disc herniations occur at the L4-L5 or L5-S1 discs.

What causes a disc prolapse?

Discs often rupture suddenly as a result of excessive pressure. Bending and heavy lifting is a typical mechanism of injury.

Intervertebral discs sometimes rupture following the application of a smaller amount of force. This is usually in the context of weakened annular disc fibres from repeated injuries over the years. This may also occur as part of the aging process of the spine.

How does a disc herniation cause symptoms such as pain?

Ruptured discs may cause pain due to two mechanisms:
  1. Direct pressure on the nerves in the spinal canal.
  2. Chemical irritation of the nerve roots by the nucleus pulposus.

A combination of these two mechanisms may cause pain, weakness, and/or numbness in the leg(s).

What are the stages of a disc herniation?

A herniated intervertebral disc may develop suddenly (over minutes or hours) or gradually (over weeks or months).

An annular tear is where the annulus fibrosis is torn, often the first event in the process of disc prolapse. An annular tear can cause back pain with or without leg pain. 
A lumbar disc prolapse (or herniation) occurs when the nucleus pulposis escapes from its usual position and bulges into the spinal canal, sometimes placing pressure on the nerves or spinal cord. There are commonly four stages:

  1. Disc Degeneration: chemical changes associated with aging cause discs to become dehydrated, collapsed and weak, but without a frank herniation. These changes can be observed on MRI scans, and are frequently asymptomatic.
  2. Disc Prolapse: the disc bulges and may cause slight narrowing of the spinal canal. This is also known as a disc bulge or protrusion.
  3. Extrusion: the soft, gel-like nucleus pulposus ruptures through the annulus fibrosus but remains within the disc.
  4. Disc Sequestration (Sequestered Disc): this occurs when the central, gelatinous portion of the disc (nucleus pulposus) is squeezed out and is also separated from the main part of the disc. The nucleus pulposus breaks therefore lies outside the disc and within the spinal canal.

 

WHAT ARE THE SYMPTOMS OF A LUMBAR DISC HERNIATION?

 

The symptoms of a herniated disc predominantly result from compression or irritation of the spinal nerves. Many people have back pain, but this is not always the case.

The symptoms of a herniated lumbar intervertebral disc include:

  • Pain running down one or both legs
  • Numbness or tingling in one or both legs
  • Muscle weakness in the leg or legs
  • Back or buttock pain
  • Bowel or bladder incontinence.

The location of symptoms depends upon which nerve(s) have been affected.

  • L5 nerve root impingement (usually from an L4-5 disc prolpase) can cause weakness of big toe extension of the big toe and ankle rxtension (foot drop). Numbness and pain can be felt on top of the foot and the outside of the calf.
  • S1 nerve root compression may cause loss of the ankle reflex and ankle weakness (e.g. patients cannot stand on their toes). Pain can radiate down the back of the leg to the sole or outside of the foot, and numbness may be found in this region.

 

How is a diagnosis made?

Making the diagnosis usually requires taking a history of the problem, a neurological examination, and an MRI scan. Important questions include:
  • Has there been an injury?
  • Where is the pain?
  • Is there any numbness?
  • Is there any weakness?
  • Have you had the same or a similar problem in the past?
  • Have you had any weight loss, fevers, or illnesses recently?
  • Have you had cancer in the past?
  • Are there any problems when you urinate or open your bowels?

 

What is a lumbar microdiscectomy and rhizolysis?

A lumbar microdiscectomy and rhizolysis is an operation on the spine in the lower back. Its purpose is to remove a disc prolapse and relieve pressure on the nerve roots that leave the spine and run down to form the nerves in your legs.

 

What is an interspinous distractor?

In some cases an interspinous distractor (X-Stop or Diam) is inserted between the pointy portions of bone at the back of the spine (the ‘spinous processes’). These ‘shock absorbers’ may reduce the pressure on the disc, as well as increasing the amount of room for the nerves in the spinal canal, lateral recesses, and intervertebral foraminae. Interspinous distractors are sometimes used as an adjunct to a microdiscectomy.

Why might I need a lumbar microdiscectomy and rhizolysis?

A lumbar microdiscectomy is used to treat intervertebral disc herniations which do not improve with conservative treatment.

Surgery is usually recommended when all reasonable conservative measures (pain medications, nerve sheath injections, physical therapy, hydrotherapy, pilates etc.) have failed. In cases of significant instability or neurological problems, surgery may be the appropriate first option.

Why might I need an interspinous distractor?

Interspinous distractors are sometimes placed in conjunction with a lumbar microdiscectomy. The goal is to offer some protection to an already injured or diseased intervertebral disc, create more room for the nerves in the locations where a simple decompression is not usually satisfactory (in the intervertebral foramen), and hopefully reduce the risk of post-operative back pain or recurrent leg pain.

What are osteophytes?

Osteophytes are abnormal bony spurs which form as part of the degenerative process, osteoarthritis or following a longstanding disc prolapse. This extra bone formation can cause lumbar canal stenosis as well as intervertebral foraminal stenosis, resulting in compression of the spinal nerves.

What is subarticular or lateral recess stenosis?

Within the spinal canal in the lumbar (lower back) region, the nerves run across the intervertebral disc and just under the facet joints (subarticular region). They may therefore be compressed by a bulging disc, or anything that reduces the amount of space in the subarticular (or lateral recess) compartment. For example, in spinal osteoarthritis, the facet joints may enlarge (‘facet joint hypertrophy’) and the ligament may thicken (‘ligamentum flavum hypertrophy’), with the end result being subarticular and lateral recess stenosis. As part of the degenerative or osteoarthritic process, additional bone may form at the margins of the disc, and these bony spurs are known as ‘osteophytes’. Osteophytes commonly contribute to compression of the nerves in the spine.

What are the surgical options?

In a lumbar microdiscectomy, your neurosurgeon removes a small portion of the lamina— the bone which forms a roof over the spinal canal. Part of the facet joint is also removed and the disc prolapse is removed.

Spinal fusion permanently joins two or more vertebral bones, and may be especially helpful in cases when one or more vertebrae slip out of their correct position. It can be done alone or at the same time as a laminectomy or laminotomy. To fuse the spine, a carbon or PEEK cage filled with tricalcium phosphate and bone chips is placed in the disc space after the disc has been removed. Screws are inserted into the pedicles of the bones and they are connected with rods. In some cases a fusion is performed without screws or cages (non-instrumented fusion). Fusion will be discussed further in a separate section.

An approach sometimes used concurrently with microdiscectomy is the insertion of dynamic stabilization devices, such as the X-Stop interspinous distractor.

The results of lumbar microdiscectomy are usually good. Generally over 90% of patients have a significant reduction in their leg pain after surgery.

What are the alternatives to decompressive lumbar surgery?

A number of alternatives to a lumbar microdiscectomy may exist, depending upon your individual circumstances. These include:
  1. Pain medications
    A number of medications may be useful for pain. These include the standard opioid and non-opioid analgesic agents, membrane stabilising agents and anticonvulsants, as well as the most recent agent to be released- Pregabalin. Special medical treatments such as Ketamine infusions may be appropriate in some situations.
  2. Nerve sheath injections
    Local anaesthetic may be injected through the skin of the back, under CT scan guidance, around the compressed nerve. This is also known as a ‘foraminal block’. Patients frequently obtain a significant benefit from this procedure, and surgery can sometimes be delayed or even avoided. Unfortunately, the benefit obtained from this procedure is usually only temporary, and it tends to wear off after several days, weeks, or sometimes months. This procedure is also an excellent diagnostic tool, especially when the MRI scan suggests that multiple nerves are compressed and your neurosurgeon would like to know exactly which nerve is causing your symptoms.
  3. Physical therapies
    These include physiotherapy, osteopathy, hydrotherapy, chiropactic and massage.
  4. Activity modification
    Sometimes simply modifying your workplace and recreational activities, to avoid heavy lifting and repetitive bending or twisting, allows the healing process to occur more quickly.
  5. Other surgical approaches
    These include interspinous distractor insertion, lumbar fusion, and artificial disc replacement. You should discuss these alternatives, together with their potential risks and benefits, with your neurosurgeon.
  6. Alternative procedures include chemonucleolysis, percutaneous discectomy (with or without use of laser), or endoscopic discectomy.

 

What are the goals (potential benefits) of surgery?

The goals of a lumbar microdiscectomy include the relief of pain, numbness, tingling and weakness.

The rationale, aims, and potential benefits of surgery may therefore include:

  • Relief of neural compression
  • Pain alleviation
  • Medication reduction
  • Prevention of deterioration
  • Stabilisation of the spine (if an interspinous distractor is used)

Generally, the symptom that improves the most reliably after surgery is buttock and leg pain. Back pain may or may not improve (occasionally it can be worse). The next symptom to improve is usually weakness. Your strength may not return completely back to normal, however. Improvement in strength generally occurs over weeks and months. Numbness or pins and needles may or may not improve with surgery, due to the fact that the nerve fibres transmitting sensation are thinner and more vulnerable to pressure (they are more easily permanently damaged than the other nerve fibres). Numbness can take up to 12 months to improve.

The chance of obtaining a significant benefit from surgery depends upon a wide variety of factors. Your neurosurgeon will give you an indication of the likelihood of success in your specific case.

How does Revision Surgery differ?

Revision surgery (ie. surgery after a previous spinal surgical procedure) often requires the removal of scar tissue.

The risk of complications from lumbar spine revision surgery is significantly higher than in first-time procedures. This is due to a number of factors, particularly scar tissue formation around the nerve roots. It is also more difficult to relieve pain and restore function in revision surgery. It is important be aware that the possibility of experiencing long-term back pain is increased with revision surgery.

What are the possible outcomes if treatment is not undertaken?

If your condition is not treated appropriately (and sometimes even if it is), the possible outcomes may include:
  • Ongoing pain in the leg(s) and/or back
  • Paralysis/weakness/numbness of the leg or legs
  • Impaired leg and/or lower back function
  • Bowel and bladder control, erectile dysfunction: ‘cauda equina syndrome’
  • Problems with walking and balance

 

What are the specific risks of lumbar spine surgery?

Generally, surgery is fairly safe and major complications are uncommon. The chance of a minor complication is around 3 or 4%, and the risk of a major complication is 1 or 2%. Over 90% of patients should come through their surgery without complications.

The specific risks of a lumbar microdiscectomy include (but are not limited to):

  • Fail to benefit symptoms or to prevent deterioration
  • Worsening of pain/weakness/numbness
  • Infection
  • Blood clot in wound requiring urgent surgery to relieve pressure
  • Cerebrospinal fluid (CSF) leak: this risk is much higher in revision (re-operation) surgery
  • Surgery at incorrect level (this is rare, as X-rays are used during surgery to confirm the level)
  • Blood transfusion
  • Injury to bowel or abdominal blood vessels
  • Implant failure, movement, or malposition (if an interspinous distractor is used)
  • Recurrent disc prolapse or nerve compression (the risk is around 10%)
  • Nerve damage (weakness, numbness, pain) occurs in less than 1%
  • Quadriplegia (paralysed arms and legs)
  • Incontinence (loss of bowel/bladder control)
  • Impotence (loss of erections)
  • Chronic pain (may require further surgery, usually a fusion)
  • Instability (may require further surgery, usually a fusion)
  • Stroke (loss of movement, speech etc)
  • Blindness (extremely rare)

 

What are the risks of anaesthesia and the general risks of surgery?

Having a general anesthetic is generally fairly safe, and the risk of a major catastrophe is extremely low. All types of surgery carry certain risks, many of which are included in the list below:
  • Significant scarring (‘keloid’)
  • Wound breakdown
  • Drug allergies
  • DVT (‘economy class syndrome’)
  • Pulmonary embolism (blood clot in lungs)
  • Chest and urinary tract infections
  • Pressure injuries to nerves in arms and legs
  • Eye or teeth injuries
  • Myocardial infarction (‘heart attack’)
  • Stroke
  • Loss of life
  • Other rare complications

 

What are the implications of surgery?

Most patients are admitted on the same day as their surgery; however some patients are admitted the day before. Patients admitted the day before surgery include those who: reside in country regions, interstate, or overseas; have complex medical conditions or who take warfarin; require further investigations before their surgery; are first on the operating list for the day. You will be given instructions about when to stop eating and drinking before your admission.

You will be in hospital for between 1 and 3 days after your surgery. You will be given instructions about any physical restrictions that will apply following surgery, and these are summarised later in this section.

Several X-rays of your back will be taken during surgery to make sure that the correct spinal level is being fused, and also to optimise the positioning of the interspinous distractor (if this is being done). It is critical that you inform us if you are pregnant or think you could possibly be pregnant, as X-rays may be harmful to the unborn child.

There is significant variability between patients in terms of the outcome from surgery, as well as the time taken to recover. You will be given instructions about physical restrictions, as well as your return to work and resumption of recreational activities. You should not drive a motor vehicle or operate heavy machinery until instructed to do so by your neurosurgeon.

You should not sign or witness legal documents until reviewed by your GP post-operatively, as the anaesthetic can sometimes temporarily muddle your thinking.

What do you need to tell the doctor before surgery?

It is important that you tell your surgeon if you:
  • Have blood clotting or bleeding problems
  • Have ever had blood clots in your legs (DVT or deep venous thrombosis) or lungs (pulmonary emboli)
  • Are taking aspirin, warfarin, or anything else (even some herbal supplements) that might thin your blood
  • Have high blood pressure
  • Have any allergies
  • Have any other health problems

 

What do I need to do before surgery?

Before you surgery it is imperative that you stop smoking.

If you are fairly overweight, it is advisable that you engage in a sensible weight loss program before you surgery. Please discuss this with your GP and neurosurgeon.

In order to prevent unwanted bleeding during or after surgery, it is critical that you stop taking aspirin, and any other antiplatelet (blood-thinning) medications or substances including herbal remedies at least 2 weeks before your surgery.

If you normally take warfarin, you will usually be admitted to hospital 3 or 4 days before your surgery. Your warfarin will be ceased at that time (it takes a few days to wear off) and you may be commenced on shorter-acting anti-clotting agents for a few days. These can then be stopped a day or so before surgery.

Ideally, you should take a Zinc tablet a day, commencing one month before surgery, and continuing for 3 months after. This should help wound healing.

Will I need further investigations?

Most patients will have had X-rays of their back, as well as a CT scan and MRI. Sometimes ‘dynamic’ X-rays of the lumbar spine are performed, with X-rays taken bending forwards and backwards; this is to determine the presence and site of any instability.

In some patients there is uncertainty either about the diagnosis or exactly which disc or discs in the back are responsible for their symptoms: in those patients, nerve conduction studies and/or a nerve block may shed light on the diagnostic issues.

If you have not had an MRI for over 12 months before your surgery, or if your symptoms have changed significantly since your most recent MRI, then this investigation will need to be repeated to make sure that there are no surprises at the time of surgery!

Who will perform surgery? Who else will be involved?

Surgery will be carried out by your Precision Neurosurgery surgeon. A surgical assistant will be present and an experienced consultant anaesthetist will be responsible for your general anaesthetic.

How is a lumbar microdiscectomy performed?

A general anaesthetic will be administered to put you to sleep. A breathing tube (‘endotracheal tube’) will be inserted and intravenous antibiotics and steroids injected (to prevent infection and post-operative nausea). Calf compression devices will be used throughout surgery to minimise the risk of developing blood clots in your legs. You will be placed face-down on the operating table on a special spinal frame.

Your skin will be cleaned with antiseptic solution and some local anaesthetic will be injected.

The skin incision is usually about 2-4cm in the middle of you lower back. It is vertical.

The bony structures of your spine are carefully defined, and using microsurgical techniques, a fine high-speed drill is used to shave some bone away over the top of the nerves. The ligament is then detached and removed and the underlying nerve root is identified. The nerve root is decompressed (this is known as a ‘rhizolysis’) and the disc is visualised.

A microdiscectomy is performed. This is done by first cutting the outer annulus fibrosis (fibrous ring around the disc) and removing the nucleus pulposus (the soft inner core of the disc). Disc removal is performed using a combination of special instruments.

During the procedure at least one X-ray is performed to check that the operation is being carried out at the correct disc level. At the end of the decompression, a small piece of fat is taken from beneath the skin and placed over the nerve root to minimise scarring. The surgical field is checked for excessive bleeding or any other problems, and a final check is made to ensure that the nerves are no longer under pressure.

If an interspinous distractor is being inserted, this is the final step of the operation. It is placed between the midline ‘spinous processes’ at the back of the spine.

The wound is closed with dissolving sutures.

What happens immediately after surgery?

It is usual to feel some pain after surgery, especially at the incision site. Pain medications are usually given to help control the pain. While tingling sensations or numbness is common, and should lessen over time, they should be reported to your neurosurgeon.

Most patients are up and moving around within a few hours of surgery. In fact, this is encouraged in order to keep circulation normal and avoid blood clot formation in the legs.

You will be able to drink after 4 hours, and should be able to eat a small amount later in the day.

You can be discharged home when you are comfortable. Some patients benefit from a short period of time (usually around a week) in an inpatient rehabilitation facility.

What happens after discharge?

You should be ready for discharge from hospital 1-3 days after surgery. Your GP should check your wounds 4 days after discharge.

You will need to take it easy for 6 weeks, but should walk for at least an hour every day. You should avoid sitting for more than 15-20 minutes continuously during this time.

During the first 2 weeks after surgery, you should not drive. At 4-6 weeks it is likely that you will be able to return to work on “light duties”. This, and the step-wise progression in your physical activities, will be determined on an individual basis.

Bear in mind that the amount of time it takes to return to normal activities is different for every patient. Discomfort should decrease a little each day. Increases in energy and activity are signs that your post-operative recovery is progressing well. Maintaining a positive attitude, a healthy and well-balanced diet, and ensuring plenty of rest are excellent ways to speed up your recovery.

Signs of infection such as swelling, redness or discharge from the incision, and fever should be brought to the surgeon’s attention immediately.

You will be reviewed after 6-8 weeks by your neurosurgeon. Until then, you should not lift objects weighing more than 2kg, and should not engage in bending or twisting movements.

The results of spinal surgery are not as good in patients who smoke or are very overweight. It is therefore important that you give up smoking permanently before your surgery and try to lose as much weight as possible.

You should continue wearing your TED stockings for a couple of weeks after surgery.
Detailed discharge instructions are as follows:

Diet: Maintain normal healthy diet, high in fibre to avoid constipation
Medications: You may be prescribed analgesia, muscle relaxants, and stool softeners. Be aware that analgesics tend to cause constipation. Please take only the analgesia that has been prescribed for you.
Activity: Allowances

-

Frequent short walks (at least 1-2 hours per day) or as directed by your neurosurgeon.

- Travelling by car is allowed for short distances. If you are making longer trips, break the trips up into 20 minute segments, getting out of the car to go for a short walk.
- Walking up and down stairs.
Restrictions(aimed at protecting
your back
and allowing healing to occur)

-

No sitting for longer than 20 minutes at a time or as directed by your neurosurgeon
- Do not bend from the waist (you should bend at the knees)
- No twisting
-

No stretching or reaching for items above your head

- Sleep with a pillow between your knees when lying on your side
- Do not lift anything heavier than 2kg for the first 6 weeks post-operatively. Light housework only – no hanging washing out on the line, carrying baskets of clothing, no vacuuming, lawn mowing.
- No driving for at least 2 weeks after surgery (6 weeks if you have had a fusion)
- No vigorous exercising/playing sports until you are cleared by neurosurgeon to commence these.

Strict bed restIS NOTrequired or recommended.

Smoking: Smoking impairs wound healing and fusion. Stopping smoking will probably improve outcomes.
Wound Care:
  • You will have either dissolvable sutures or staples
  • Have GP check your wound 4 days after discharge. A new dressing will be applied and this is to remain on for a further 4 days then is to be removed. If you have staples your GP will usually remove them 7-8 days after surgery.
  • Keep wound dry for 12 days after surgery.
  • Shower if the dressing is intact. If the wound becomes moist, it will need to be dried and a new dressing applied.
  • Report any redness, discharge, persistent oozing or drainage from the wound to your GP or to the Precision Neurosurgery Registered Nurse.
  • Avoid swimming, spas or baths until your wound has completely healed, or until you are cleared by your neurosurgeon to commence these.
  • Keep taking your Zinc tablets daily for 3 months after surgery (this helps wound healing).
  • You should gently rub Vitamin E cream into your wound commencing 3 weeks after surgery and continuing for 6-12 months (this may reduce scarring).

What do I need to tell my surgeon about after the operation?
You should notify your neurosurgeon and should also see your GP if you experience any of the following after discharge from hospital:

  • Increasing leg pain, weakness or numbness
  • Worsening back pain
  • Problems passing urine or controlling your bladder or bowels
  • Problems with your walking or balance
  • Fever
  • Swelling, redness, increased temperature or suspected infection of the wound
  • Leakage of fluid from the wound
  • Pain or swelling in your calf muscles (ie. below your knees)
  • Chest pain or shortness of breath
  • Any other concerns


What are there
results of surgery?

Overall, over 90% of patients will obtain a significant benefit from surgery, and this is usually maintained in the long term.

Generally, the symptom that improves the most reliably after surgery is leg pain. Back pain may or may not improve (very occasionally they can be worse). The next symptom to improve is usually weakness. Your strength may not return completely back to normal, however. Improvement in strength generally occurs over weeks and months. Numbness or pins and needles may or may not improve with surgery, due to the fact that the nerve fibres transmitting sensation are thinner and more vulnerable to pressure (they are more easily permanently damaged than the other nerve fibres). Numbness can take up to 12 months to improve.

What are the costs of surgery?

Private patients undergoing surgery will generally have some out-of-pocket expenses.

A quotation for surgery will be issued, however this is an estimate only. The final amount charged may vary with the eventual procedure undertaken, operative findings, technical issues etc. Patients are advised to consult with their Private Health Insurance provider and Medicare to determine the extent of out-of-pocket expenses.

Separate accounts will be rendered by the anaesthetist and sometimes the assistant, and hospital bed excess charges may apply. Medical expenses may be tax deductible (you should ask your accountant).

You should fully understand the costs involved with surgery before going ahead, and should discuss any queries with your surgeon.

What is the consent process?

You will be asked to sign a consent form before surgery. This form confirms that you understand all of the treatment options, as well as the risks and potential benefits of surgery. If you are unsure, you should ask for further information and only sign the form when you are completely satisfied.