Injecting local anaesthetic around this nerve junction blocks the pain messages, causing the pain to be reduced.
An anti-inflammatory steroid may be injected with the local anaesthetic. If required, only a small amount of steroid is needed and it will not cause any of the side effects sometimes associated with taking steroid tablets. They are not the same kind of steroids that athletes may take.
Blocking the sympathetic nerves also causes the blood vessels in the legs to dilate, meaning they become wider. This will improve the blood supply in patients that are having pain because of poor circulation.
What has gone wrong?
Your sympathetic nerves have started sending pain messages. It is not at all clear why this happens. It is known that by blocking the activity of the sympathetic nerves the pain can be reduced.
Often the pain is related to poor circulation. When the blood vessels to the legs are narrowed or diseased, this pain can happen. The block helps by dilating the blood vessels in the legs, which improves blood circulation.
The aim of the procedure is to reduce the signals sent by the sympathetic nerves, which in turn reduces the pain. The procedure will also improve the circulation of the legs and may improve pain caused by ischaemia, which is a poor blood supply.
Your pain should be reduced and you should be able to move around more easily. If successful, this treatment can reduce the need for tablet medications.
Are there any alternatives?
By the time that you consider having a lumbar sympathetic block you should have already tried other more simple treatments. These include rest, both painkilling and anti-inflammatory tablets, and physiotherapy with exercise.
You may have also tried a transcutaneous electrical nerve stimulation (TENS) machine for the pain. This works by sending soothing pulses across the surface of the skin and along the nerve fibres. The pulses prevent pain signals from reaching the brain. They also stimulate your body to produce higher levels of its own natural painkillers, called endorphins.
Sometimes, even the strongest painkillers, like morphine, will have been tried.
What if you do nothing?
If you do nothing there are several things that may happen:
With time and rest the pain may settle on its own
The pain and difficulty in performing daily activities may remain the same
The pain may increase and spread
Your posture may get worse, making activities and even sleeping more difficult
If the pain is due to poor circulation, other treatments and maybe even operations may be needed
Who should have it done?
The following groups of patients should have the procedure done:
Patients with pain in the leg or lower back that has failed to respond to standard treatments
Patients with pain in the leg or lower back with symptoms suggesting that the sympathetic nerves are involved
Patients with poor blood circulation in the legs
Who should not have it done?
Each patient must make the final decision on whether to proceed or not. If you are unhappy about the procedure for any reason you should not continue.
There are specific medical situations when a lumbar sympathetic block should not be done and they are as follows:
When a patient is on medication that prevents blood from clotting, such as warfarin. This would lead to more bleeding than normal. It may be possible to stop the medication a few days before the procedure. This will need to be discussed with your doctor
When a patient is suffering from an illness that prevents blood from clotting, such as haemophilia. This would also lead to more bleeding than normal
When there is infection of the skin over the site where the needle needs to be put in. This could lead to infection in the deeper tissues
Author: Dr Sean White FRCA. Consultant in pain and anaesthesia.
© Dumas Ltd 2006