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Sciatica

What is sciatica?

Sciatica is a type of neuralgia (nerve pain). The sciatic nerve is a huge nerve (about the size of an adult's small finger) that controls the function of the leg, especially the foot. It passes from the spine into the buttock, then into the back of the thigh and leg.

What causes sciatica?

It is caused by pressure, usually from a prolapsed disc, on the nerve roots from the lower back that form the sciatic nerve. This problem is often called a 'slipped disc', but it is not a good term because the disc is big and only part of it bulges to cause pressure.

Sciatica can be caused also by the nerve roots being trapped in the tunnel at the side of the spine through which they pass. This pinching effect causes the nerve to become irritated and swollen. The tunnel is made smaller by surrounding arthritis or a flattened disc space. This problem is quite common in elderly people.

A rare cause is a haemorrhage around the nerves in people who are taking blood-thinning tablets.

What are the symptoms?

The patient usually feels a burning pain or a deep aching pain in the buttock, the thigh, the calf and the outer border of the leg, ankle and foot. Sciatica is not a pain covering the whole leg like a stocking. It commonly causes a pain around the outer part of the leg into the ankle. The pain may vary from very severe to mild. A 'pins and needles' sensation or numbness may be felt in the lower leg and the foot.

The pain is usually made worse if you sneeze, cough, strain at the toilet or lift something.

What are the risks?

Fortunately most cases of sciatica gradually get better in about 6 weeks. Sometimes the pressure on the nerve is so great that the leg, especially the foot, becomes weak and floppy. In such cases, an operation is required to relieve the pressure.

Rarely a disc prolapse will cause severe weakness and numbness in the legs, and lack o control of the bladder or bowels. This is very serious and needs urgent attention.

What is the treatment?

Rest

When the pain is acute, it is most important to rest lying down for 2 or 3 days. You should do nothing but rest on a firm mattress or on the floor, getting up only to go to the toilet.

After the acute phase, you should take things gently to allow the problem to settle. Avoid lifting, bending your back and sitting in soft chairs for long periods.

Medication

Your doctor will prescribe some tablets for your pain and perhaps some tablets to relieve inflammation around the nerve.

Exercises

These are very good if you can manage them, and swimming is one of the best. Your doctor will advise you.

Other treatments

Your doctor could advise traction, gentle mobilisation of your lower back or epidural injections to accelerate healing. Some people find electrical stimulation and acupuncture helpful.

Copyright 1995: John Murtagh, Professor of General Practice
Monash University, Melbourne, Australia