Sciatica

Causes of sciatica

Slipped (or prolapsed) disc

Your spine is made up of vertebrae, discs and nerves. Vertebrae are the blocks of bone that make up the structure of your spine and protect the nerves. The vertebrae are supported and cushioned by the intervertebral discs. The discs are made from a tough, fibrous case that contains a softer jelly-like substance. A slipped disc occurs when the outer part of the disc tears, allowing the jelly inside to bulge and protrude outwards between the vertebrae. When this presses against the sciatic nerve, it can cause sciatica.

As a person gets older the discs become harder, tougher and more brittle. Repeated strain on the back means there is a greater chance of a hardened disc splitting and rupturing.

Spinal stenosis

Spinal stenosis is the narrowing of nerve passages in the spine. It occurs when the bones, ligaments or discs of the spine squash the nerves of the spine causing pain, usually in the lower back and legs. It mainly affects people in their late middle age and older.

Causes of spinal stenosis include:

• age-related changes in the spine
• changes in the ligaments of the spine
• diseases of the bone, such as Paget's disease

Other causes

Less commonly, sciatica may be caused by:

• infection
• injury
• a growth within the spine, such as a tumour

Cauda equina syndrome

Cauda equina syndrome is a rare but serious condition that can cause sciatica. The cauda equina is the name given to the bundle of nerves that lead out from the end of the spinal cord. “Cauda equina” means “horse’s tail”, and the bundle of nerves at the bottom of the spinal cord look just like a horse’s tail. Cauda equina syndrome occurs when these nerves are compressed and damaged. It can eventually lead to paralysis if left untreated.

One of the warning signs of cauda equina syndrome is suddenly losing control of your bladder or bowels. If this happens, you need to see a doctor immediately, because if the nerves are not surgically decompressed straight away, it can lead to permanent incontinence of the bladder or the bowels.

A large disc prolapse is the most common cause of cauda equina syndrome.

Diagnosing Sciatica

If the symptoms of sciatica are mild, a medical diagnosis is not usually needed. This is because mild, short-term (acute) sciatica is normally not a cause for concern and will improve without treatment. However, if your symptoms are severe or the condition continues for more than six weeks, seek help from Dr Allfree at The Mansfield Clinic. Dr Allfree has many years’ experience in treating people with sciatica.

Straight leg raise test

Dr Allfree will be able to confirm that the pain is being caused by the sciatic nerve using the passive straight leg raise test. This test involves lying flat on your back with your legs straight. Dr Allfree will raise one leg and then raise your foot up at the same time. If this causes pain or makes your pain worse, it is usually an indication that your pain is being caused by the sciatic nerve.

Warning signs

Dr Allfree will also ask you questions about your medical history and individual circumstances. He is looking for warning signs that your sciatica is caused by a serious condition, such as cauda equina, an infection of the spine, or cancer.These warning signs are called 'red flags’. Red flags that suggest cauda equina syndrome are:

• numbness in your bottom, lower back and leg
• loss of bladder and/or bowel control
• feeling of weakness in your leg and foot 

Red flags that suggest cancer or infection are:

• you are over 50 years of age and have never had any previous back pain
• you have a history of cancer
• you have symptoms of fever, chills or unexplained weight loss
• you have had a recent bacterial infection, such as a urinary tract infection
• you inject illegal drugs, such as heroin or cocaine (a leading risk factor for spinal infections)
• you have a condition that weakens your immune system, such as HIV
• you have a structural deformity of the spine

If you have one or more red flags, you will be referred for further tests. If you have any red flags that suggest cauda equina, you will need to be admitted to hospital immediately.

Further tests

Depending on your symptoms, Dr Allfree may feel it is necessary to have further tests These may include:

• a blood test to rule out infections
• an x-ray
• imaging tests such as an MRI scan

MRI scans use strong magnetic waves to build up a detailed picture of the inside of your body. MRI scans take cross-sectional pictures of the spine, and allow doctors to look at the back in great detail. An MRI scan should be able to detect any problems with the nerves and structure of your spine.

Treatment for sciatica is not always necessary, as the condition can improve naturally within around six weeks. However, if your symptoms are severe or persistent, a number of treatments are available. These usually include self-help and conservative treatments, such as medication and manual therapy such as osteopathy.

In a small number of cases, surgery may be recommended to correct the problem in your spine that is thought to be causing your symptoms.

Self-help

There are a number of things you can do yourself to help reduce the symptoms of sciatica. These include remaining as active as possible, using hot or cold compresses, and taking simple painkillers, such as paracetamol or ibuprofen.

Exercise

If you have sciatica, it is important for you to remain as physically active as possible.

Simple exercises, such as walking and gentle stretching, can help reduce the severity of your symptoms and strengthen the muscles that support your back. While bed rest may provide some temporary pain relief, prolonged bed rest is considered unnecessary and unhelpful.

If you have had to take time off work due to sciatica, you should aim to return to work as soon as possible.

Compression packs

Some people find that using either hot or cold compression packs on painful areas can help to reduce the pain. You may find it effective to use one type of pack followed by the other. Custom-made ice packs are available from the Mansfield Clinic.

Painkillers

If you have persistent or troublesome sciatic pain, there are a number of painkilling medications that may help. These include:

• paracetamol and non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen
• stronger medication, such as codeine or, in severe cases, morphine
• certain antidepressants such as amitriptyline – whilst these medications were originally designed to treat depression, they have since been found to help relieve nerve pain
• certain anti-epilepsy drugs such as gabapentin – like antidepressants these can also be useful for treating nerve pain

These medications are not suitable for everyone, particularly when used in the long term. Some of these medications can also cause significant side effects in some people. 

If the painkilling medications don't help, Dr Allfree will discuss with you a number of other treatment options.

Spinal injections

If other methods of pain relief have not worked, Dr Allfree may recommend a caudal epidural steroid injection. This delivers strong anti-inflammatory and painkilling medication directly to the inflamed area around the nerves of your spine, which may help release the pressure on your sciatic nerve and reduce your pain.

Osteopathy

In some cases, Dr Allfree may recommend treating you with osteopathy. Osteopathy can help to improve the flexibility of your spine. A special regime of back exercises may also be beneficial.

Surgery

Surgery is rarely necessary to treat sciatica, although it may be considered if the condition has an identifiable cause, such as a slipped disc, the symptoms have not responded to other forms of treatment, or the symptoms are getting progressively worse. 

The type of surgery recommended will depend on the cause of your sciatica. Some surgical options include:

• Discectomy – where the part of the herniated disc pressing on your nerve is removed. This is the most common type of surgery required for sciatica, and as spinal surgical procedures go, it is relatively straightforward.
• Fusion surgery – it may be possible to fuse a vertebra that has slipped out of place by using a metal or plastic cage between the vertebra, supported with metal rods and screws. Spinal fusion surgery is not straightforward, and is not normally the first procedure that a spinal surgeon will recommend.
• Laminectomy – a procedure often used to treat spinal stenosis, where a section of vertebrae called the lamina is removed, allowing more room for the spinal nerves to exit the spine

Many people have a positive result from surgery but, as with all surgical procedures, spinal surgery carries risks. Potential complications range from the relatively minor, such as an infection at the operation site, to the more serious, such as permanent damage to the spinal nerves.

If the opinion of a spinal surgeon is needed, Dr Allfree will be able to arrange a referral.

Before choosing spinal surgery, your surgeon will discuss the relative risks and benefits with you.

Preventing sciatica

There are some steps you can take to minimise your risk of a slipped disc or back injury that could lead to sciatica. This includes:

• better posture and lifting techniques at work
• stretching before and after exercise
• simple, regular exercises to improve flexibility