Sympathetic nerves are nerves that control 'autonomous' functions of the body, that is functions that are not controlled consciously, such as heart rate, sweating and blood flow.
They run down the spine, following a separate path from the spinal cord, located instead to the front of the spine. Pain signals can run in these sympathetic nerves.
Sympathetic nerve blocks are generally used to treat neuropathic pain.
A sympathetic nerve block temporarily disables pain signals transmitted via the sympathetic nervous system via a local anaesthetic being injected directly into the nerves. It can be administered as a diagnostic tool to help characterise the pain, or it can be used to actually treat the pain.
In some cases, a sympathetic nerve block (or series of them) may give prolonged relief from pain.
The most commonly performed sympathetic blocks are stellate ganglion blocks for pain of the face or arm, or lumbar sympathetic block for the legs and some abdominal organs.
- Neuropathic pain.
- Complex regional pain syndrome.
- Chronic visceral pain.
- Hyperhidrosis (excess sweating).
- Some vascular insufficiency syndromes.
You should avoid undergoing any other medical procedures, such as for example dental treatment or a colonoscopy, within 48 hours (before or after) of a sympathetic nerve block. You should also not have anything to eat or drink prior to the procedure.
Please also let us know ahead of the procedure if…
- You are taking any antibiotics.
- You have a pacemaker or defibrillator.
- You have any allergies.
- You are diabetic.
- You are ill (in which case we may need to postpone the procedure).
You should not drive yourself to or from the appointment, or drive in the 24-hour period immediately after the procedure.
The procedure generally takes no longer than 15 minutes (although we recommend allowing around one hour for the appointment), and involves an injection to the front of the neck in the case of stellate ganglion block, or the side of the bony lumbar spine, in the case of lumbar sympathetic block.
You are asked to lie down on a special fluoroscope (real time X-ray) table, and an IV line is put in place in your arm or hand (in case light sedation is required).
The injection site is then cleaned and numbed with a local anaesthetic and a thin needle is inserted at the injection site and then guided (use the fluoroscope image) to the correct position.
Before the anaesthetic is injected, a small quantity of contrast dye is introduced to check that the anaesthetic will get to the target area.
Once the procedure is complete, you will need to spend around half an hour under observation before being able to go home. While under observation you will be asked to see if you can reproduce the pain you normally feel and let the doctor know if there has been any reduction in pain, and how much.
A sympathetic nerve block is a relatively low-risk procedure – however all medical treatment comes with some level of risk. Possible complications may include…
- Pain at injection site.
- Damage to adjacent anatomical structures.
- Allergic reaction to anaesthetic or contrast dye.