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Lumbar Chemical Sympathectomy

We hope the information on this page will be helpful to you. If you have any questions please ask a member of the Pain Relief Clinic nursing staff who will be happy to help you.

The procedure that you have had done to you is known as a Lumbar Chemical Sympathectomy Injection. A long-acting local anaesthetic called phenol is injected under X-ray control on to the sympathetic nerves which modify the state of the blood vessels in your leg and affect the feeling indirectly i.e. numbing these nerves does not actually numb the leg but can alleviate pain travelling in other nerves which carry pain. By improving blood flow into the leg, pain can also be reduced. Using local anaesthetic only, the result may be temporary. The increased warmth in your leg may only last a few weeks, although pain relief can last much longer than this.


When is it used?

This injection is done for a variety of conditions, often for poor circulation in the legs, but also for certain other chronic back and leg pains.

As a rule, after-effects are very mild. Soon after the injection there may be a feeling of numbness in parts of the leg on that side. This is very temporary and is due to the local anaesthetic used to make the injection bearable. As the injection results in more blood flowing into the limb, there is often a feeling of light-headedness and dizziness on standing for up to a day or so afterwards. You should sit or lie down if you have these symptoms. A good fluid intake is advisable. The decision to give one or both types of treatment is dependent on the type of disease. The doctor will have discussed the need for this treatment with you.


A good result will produce an artificial ‘blush’ in the leg as the blood vessels open up. The limb will feel warmer than the other leg. If the injection is done for a painful condition, there should hopefully be a lessening of the pain when this happens, but it may take several days. As there is more blood flowing into the limb as a result, there is often some swelling due to accumulated fluid. If this occurs, you should elevate your leg when sitting for prolonged periods. This effect lessens as you increase your mobility.


There might be some temporary soreness in the back due to the needle insertion. Simple pain killers are sufficient to tide you over this. However, about one in six patients unfortunately get a burning tingling pain at the top of the thigh in front, typically starting after a week and this can last for 4 to 6 weeks. This is known as ‘postsympathectomy neuralgia’. It always goes away on its own and the best you can do is to take painkillers while it lasts.

If possible, you should go to bed or at least lie down when you return home. The following day you can return to normal activities.


Please contact the clinic (01604) 545065 about 4 weeks afterwards to report the result to us. If this injection is done for the relief of poor circulation and you were referred by a surgeon, then he will be seeing you in his outpatients in due course.


After the injection you must not drive a motor vehicle for the remainder of the day.


Useful Websites


Other Information

Northampton General Hospital operates a smoke-free policy. This means that smoking is not allowed anywhere on the Trust site, this includes all buildings, grounds and car parks.

Leaflets, information, advice and support on giving up smoking and on nicotine replacement therapy are available from the local Stop Smoking helpline on 0845 6013116, the free national helpline on 0300 123 1044, email: and pharmacies.

Car parking at Northampton General Hospital is extremely limited and it is essential to arrive early, allowing ample time for parking. You may find it more convenient to be dropped off and collected.

This information can be provided in other languages and formats upon request including Braille, audio cassette and CD. Please contact (01604) 523442 or the Patient Advice & Liaison Service (PALS) on (01604) 545784, email:



Updated February 2021

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