Patient Information Sheet   :   Spinal Decompression

What Is It?

Spinal decompression is the name given to an operation whereby the spinal column, (a combination of vertebrae or bones and the intervening soft tissues), is opened up to release some of the pressure on the nerve tissue inside.   The spinal column is made up of blocks of bone or vertebra sitting one on top of each other.   At the front of the spinal column between the bones are shock absorbers or intervertebral discs.   At the back of the vertebral column there are small joints called facet joints which allow some movement between each of the vertebrae.    The spinal cord is in the middle of the spinal column, protected by a ring of bone.   The spinal nerve leaves at each level and goes into the body - nerves from the upper part of the spine going into the arms, nerves from the middle part going into the body and the nerves from the lower part of the spine (the lumbar spine) going into the legs.   When the nerves are compressed by the spinal canal being too narrow this is a condition known as central spinal stenosis.    This is usually due to a combination of a congenitally narrow spinal canal (something you were born with) and wear and tear changes leading to swelling of the intervertebral discs and/or the facet joints and these swellings then encroach on the available space for the spinal cord.    Sometimes, the nerves are trapped just as they are leaving the spine and this is known as lateral stenosis, i.e. at the side of the spine whereas compression of the spinal cord is known as central or canal stenosis.

The symptoms from this condition are due to irritation or pressure on the nerves leading to altered nerve activity which shows itself as tingling or numbness affecting the part of the body which the nerves go to, weakness of the muscles that the nerve controls or pain coming from the sensory fibres in the main nerve.    Typically someone with spinal stenosis has no significant problems sitting or lying down when the weight is off the spine and the spinal column is bent so that the nerve canals are opened up taking the pressure off the nerves.   However, when standing, particularly when arching backwards or walking, the bones settle onto each other and narrow the spaces between them to the extent where nerve pressure is felt as tingling or weakness (sometimes described as a feeling of heaviness) usually affecting the legs.  Thankfully two thirds of patients who have this condition will either improve or get no worse, around one third of patients with this condition gradually get worse and eventually require specialist help.

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What Treatment Choices Are Available?

In the early stages physiotherapy or osteopathy is often useful in reducing the amount of symptoms suffered, largely through advice and exercise techniques shown by the physiotherapist or osteopath.  As the condition develops and the symptoms become more troublesome drugs such as simple pain killers or anti inflammatory medications can often produce significant relief.    There is also a class of drugs known as Biphosphonates which can be used in this condition with variable amounts of success.   Once the condition gets to the stage where your day to day existence or work is being threatened due to the symptoms from your back, you would normally then be asked to see a specialist such as myself.     Once the condition is accurately diagnosed,  the extent and location of the spinal narrowing is confirmed by means of special scans called MRI scans.  These show both the soft tissues as well as the bones and can show the degree of nerve squeezing either at the lower end of the spinal cord (the so-called cauda equina) which arises from the spinal cord at the first lumbar vertebra) or the nerve roots as they leave the spinal column.  Depending on what treatment has already been undertaken, the next level of treatment beyond medication already given by your doctor and treatments advised by your physiotherapist/osteopath will be considered.   An injection of local anaesthetic and steroid (Cortisone) into the spinal column around the nerves and nerve roots can be undertaken (an epidural).  This acts to reduce swelling and inflammation and can often relieve symptoms quite dramatically.    The final option is surgical decompression of the nerves by removing bone from the spinal column.

Spinal Decompression

This operation is undertaken reasonably commonly and is one of the more successful spinal operations.   Around four out of five people who have this operation feel that the operation has been successful in terms of relieving symptoms sufficiently to have made the operation worthwhile.   This means that one in five patients therefore do not, and are either no better (around 10% of patients who undergo the operation) or who are even worse as a result of the operation (around 10% of patients).   

The operation involves a general anaesthetic and the patient being placed flat onto their front with support under their knees and chest.    An incision is made across the relevant part of the spine, usually the lumbar spine and the muscles are pushed to either side to allow the spinal column to be exposed.   I remove the back of the spine (the posterior elements) allowing visualisation of the spinal cord and nerve roots at the lower end of the spine.   I will then follow the nerve tissue out until I am sure that the relevant nerve tissue is freely mobile and the bone compressing it has been removed.     Depending on the amount of bone removed and the age of the patient, the bone is sometimes replaced (bone grafting procedure) or if so much bone has been removed to affect the stability of the spine I may elect to put in metalwork (rods and screws) into the affected bone to help support and stabilise it whilst the healing process continues.     Bone grafting procedures and using metalwork (instrumentation) adds considerably to both the complexity and risks of the operation.   Once the operation is complete I allow the muscles to fall over the exposed nerve tissue and the wound is stitched up.  

Post operatively you will be encouraged to mobilise as soon as possible in terms of moving around in bed (under the direction of the physiotherapists) and/or sitting and standing within 24-48 hours of the operation.   Most patients who have this procedure are up and about, safe and comfortable enough to go home by around five days following the operation but you will be uncomfortable when moving for around six weeks until the wound and tissues heal fully.    During that time it should become apparent whether or not the operation has been successful in terms of improving the symptoms of nerve pressure in the lower limbs.

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What Happens After Discharge From Hospital?

For the first three weeks you will be encouraged to mobilise little and often, by walking around up to a few hundred yards at a time, sitting and standing with good posture and varying your position frequently.   Each activity should be limited to no more than 15-20 minutes at a time for the first two-three week period.   Once the wound has healed and the sutures have been removed you will be encouraged to return to light exercise as comfort allows, and take on more activities such as swimming, cycling, etc.    

Given the fact that you have had major spinal surgery you will be discouraged from driving for six weeks following the operation as your insurance would be invalidated by the fact that you are likely to be in some degree of discomfort and this will obviously affect your driving skills.   In particular it will affect your ability to brake sharply. However, you can travel in a car immediately following the surgery as long as you are able to get comfortable in the car and have assistance getting in and out of the vehicle, for particularly the first two weeks.    However, you should not go on journeys for more than 15 minutes at a time until the six weeks stage.   

Most patients who undergo this surgery will have been seen by the physiotherapists on several occasions during their in-patient stay and will need to continue their physiotherapy exercises at home, but unless there is a particular reason, formal physiotherapy as an out-patient is not required.   I normally arrange to see you in the clinic at around six weeks following your operation to monitor your progress and advise on more strenuous activities at that time.

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What Can Go Wrong?

Spinal decompression is a major surgical procedure and the number of complications is endless.    Major complications thankfully are rare but can be devastating.    Along with any major operation involving the use of general anaesthetic there are risks from the anaesthetic itself, but thankfully these complications are now rare with modern anaesthetic techniques, certainly less than 1 in 1000.     In terms of the surgery there are significant complications such as :

1. Infection. Around 1 in 10 surgical wounds become infected (superficial infection) but this is often easily treated with a simple course of antibiotics.   Deep infection of the spine itself is rare (1 in 100) but much more devastating.   This is associated with formation of pus (abscess) which often requires re-operation to drain the infected material and a prolonged course of intravenous antibiotics and wound care.   The infection can get into the spinal covering and cause severe spinal infection (meningitis).    This complication is very rare.
2. Damage to the spinal cord.   Damage to the spinal cord or nerve roots again is rare, certainly less than 1 in 500.   The lumbar spine has nerve roots rather than spinal cord tissue.   These nerves control specific muscles and loss of nerve function means that sensation and movement of a joint is severely affected on one side or the other.    Damage to the spinal cord leading to extensive loss of function involving both limbs is very rare and would only normally occur in episodes of spinal decompression procedures of the neck or thoracic spine.   
3. CSF Leak. CSF (cerebro-spinal fluid) is the fluid which surrounds the nerve tissue and is enclosed by a thick membrane called the dura.  As I remove bone from around trapped nerves sometimes this membrane can be damaged leading to leakage of fluid into the tissues.    This actually happens in around  1 in 25 patients who undergo spinal surgery but is usually relatively minor and I will either patch up or stitch up the small tear at the time of surgery.   Occasionally however the leak of CSF fluid can persist after operation leading to a collection of fluid under the skin or even leakage through the wound into the dressings.   The latter situation of persisting CSF leak through the skin is known as CSF fistula and often requires re-operation to seal up the leak.     This occurs in less than 1 in 200 cases.   More usually CSF leak leads to headache or nausea which persists for a few days following the operation due to the loss of pressure of the fluid surrounding the spinal cord (and the adjoining brain).
4. Continued back pain.    Often the condition leading to spinal stenosis is associated with wear and tear arthritis, and this arthritis can cause back pain as well.  Once the spinal nerves have been decompressed this will often improve function but the patient will be left with residual arthritic pain from the spine itself.     If the amount of bone removed affects the way the lower bones or vertebrae work together it can actually cause deterioration in the wear and tear arthritic symptoms of the back.    This can occasionally necessitate further surgery to stabilise the spine.   This is unusual as I will have taken this into account at the time of the original operation and on deciding then whether or not bone grafting or instrumentation was required (see above).
5. Deep Vein Thrombosis : Pulmonary Embolus (DVT/PE).   After any major operation which involves a period of immobility or bed rest there is a tendency for blood clots to form in the veins of the lower limbs.    These blood clots (thrombosis) cause limb swelling and discomfort.  Even more worrying is when the thrombus becomes large enough such that pieces break off and travel in the veins to the heart and lungs causing significant damage (pulmonary embolism). 1 in 1000 patients who have a major spinal operation die as a result of massive pulmonary embolus.    By getting mobile as soon as possible after the operation this will reduce your risk of deep vein thrombosis and pulmonary embolus and I will often use techniques such as TED stockings, calf compression techniques in surgery and  anti coagulation such as Heparin to reduce the risk still further.   I will discuss this with you when planning surgery.
6. Failed Operation.   As noted above spinal decompression is a very successful operation generally.   Around 8 out of 10 patients who undergo this operation have significant improvement in their symptoms and feel that the operation was worthwhile.   One in ten however get worse due to complications as those outlined above and another 1 in 10 patients feel that their symptoms are no better.   This is either due to the fact that the nerve damage has become permanent due to prolonged and severe compression of the nerves or inadequate decompression of the nerve roots at the time of your surgery.    Due to persisting symptoms of nerve compression I may elect for you to undergo repeat scans of your back to see whether or not further decompression is required but this would be unusual.   More likely is that the damage to your nerves is irreversible and that the operation, although appropriate and successfully carried out, has unfortunately not resolved your symptoms.    
7. Post Operative Scarring.   Following operation the amount of scar tissue is dependent on each individual.   Sometimes the amount of discomfort from the scarring in the muscles and tissues of the back is painful and leads to discomfort on sitting, standing or stretching the scar tissue which is intrusive.  Even more worrying is when excessive scarring develops around the spinal cord and the nerves, and leads to irritation of the nerve tissue which can be as disabling and distressing as the compression caused by the bone.    Such nerve scarring (arachnoiditis) is very difficult to treat and is often made worse by further surgery, and can only be treated by pain management techniques including further injections and/or medication.   Severe nerve root scarring thankfully is rare, around 1 in 100 patients.   
8. Other Complications.    The list of complications is endless.   Other rare but possible complications of surgery include wrong level surgery such that, despite taking appropriate scans and sometimes checking the spinal levels to be operated on by xrays in theatre itself, the wrong level is operated on.  During the operation the anaesthetist will often allow the blood pressure of patients undergoing spinal decompression to fall so that the amount of bleeding is minimal.   This technique (hypotensive anaesthesia) allows a much safer operative field for me so that I can see much more clearly what I am doing.   However, sometimes the fall in blood pressure can lead to loss of blood flow into the heart and brain leading to strokes and/or heart attacks.   Because of these complications (and many others) surgery is always a last resort. This is particularly true in spinal surgery which has some of the most worrying and disabling complications related to it and should be undertaken when all other treatment avenues have been explored and have failed to improve things sufficiently to make your condition tolerable.
9. When Can I Return to Work?   Most patients who undergo spinal decompression are usually over 50 and many have not been able to work because of their condition.     For younger patients who are managing to work prior to their operation, I would normally anticipate at least up to three months before you are able to return to work and then only if your work is sedentary, i.e. office work.   Any more strenuous work, particularly that which involves prolonged sitting or bending may take up to six months before you are fit enough and safe enough to return to your work.
10. What Happens If Things Go Wrong?  Should you be unfortunate enough to develop a complication, either as an in patient or following discharge from hospital, this will be dealt with by either your own GP or myself.    Should you develop any problems you can phone the hospital ward and speak to the nursing staff on duty for advice.    They would normally be able to deal with most queries or suggest suitable alternatives such as phoning your GP, attending the accident and emergency department locally or returning to the Fitzwilliam Hospital, depending on the circumstances.

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