The sympathetic nervous system helps control many functions in your body (blood pressure, sweating, peripheral blood flow) and is usually not involved in pain sensation. However, in some pain conditions, such as Complex Regional Pain Syndrome (CRPS) or Reflex Sympathetic Dystrophy (RSD), the sympathetic nerves become activated in an abnormal way and begin to transmit pain. Blocking these sympathetic nerves can improve pain and a positive response is also useful in helping to provide a diagnosis for the pain. Sympathetic blocks are done with either x-ray or ultrasound guidance, and all involve the injection of local anesthetic around bundles of nerves. The blocks may be done initially in a series of three over a 6 week period, but in some patients may be repeated several times per year. Sympathetic blocks can be done at five different levels of the spine, depending on the area and type of pain involved:
- Stellate Ganglion Block: the Stellate Ganglion is a bundle of sympathetic nerves that lies roughly at the C7 level, or at the base of the neck. This block may be recommended if there is nerve pain in one or both arms that is difficult to treat with other methods.
- Lumbar Sympathetic Block: the lumbar sympathetic plexus is located at roughly the L3 level. Painful conditions in one or both legs, to include CRPS and some peripheral vascular disease, may respond to blockade of this plexus with local anesthetic.
- Superior Hypogastric Plexus Block: located at the L5 level, the hypogastric plexus receives pain signals from most pelvic organs. This block may be recommended if you have pelvic or low-abdominal pain.
- Ganglion Impar Block: the lowest collection of sympathetic nerves is found in the Ganglion Impar, which lies near the junction of your sacrum and coccyx. Blocks at this level may be helpful if you have coccydynia, or tail-bone pain.
How long does a sympathetic block take?
Sympathetic blocks usually take no more than 30 minutes.
How will I feel afterwards?
Relief from sympathetic blocks is usually noticed with 15 minutes of your procedure. You may also note rapid improvement in blood flow to the area, with increase in temperature and decreased sensitivity.
How long will the relief last?
Relief is variable and you may require a series of injections over several weeks to provide lasting results.