Sympathetic blockade
There are numerous ways to chemically or surgically block transmission of nerve impulses in the sympathetic nervous system. The most common is the use of a local anesthetic, ideally injected by a well-trained medical specialist under fluoroscopic guidance into the region of the stellate ganglion in the neck or the lumbar sympathetic chain in the low back. These blocks may provide temporary relief of CRPS pain and related symptoms. Response to the blocks traditionally was thought to be an important piece of information for diagnosing CRPS; however, there are many reasons why the blocks may fail, including:

• Inadequate technique on the part of the health care provider that fails to achieve a complete block.

• Absence of SMP in any given patient or at any given stage of the disease.

• Reliance on the patient’s report of pain relief, which may be influenced by multiple psychosocial factors.

• Poor record keeping by the doctor.

There are other techniques that can achieve sympathetic blockade, including injection into other areas of the body or applications of new technology, such as radiofrequency (RF) probes, and the use of a wide variety of other injected drugs. Depending on where you live, such techniques may not be available in your area. This fact has created difficulty in gathering meaningful treatment outcome data about sympathetic blockade and is one of the reasons why there remains confusion in the medical and insurance communities about the place for sympathetic blockade in the evaluation and treatment of CRPS.

One area of great concern is the place for permanent blocks in parts of the sympathetic nervous system. Permanent blocks can be achieved by the injection of chemicals, such as alcohol or phenol, by improper use of RF technology, or by surgical cutting of sympathetic nerves or ganglions. Many patients who have had these procedures get temporary relief of pain, only to be replaced months later by recurrence of pain (called “deafferentation�?pain) that is just as bad or worse than the original pain. For this reason permanent blocks (also known as “neuroablative�?procedures) are generally best limited to end-of-life care, when the patient’s life is expected to end before the appearance of such deafferentation pain.

Somatosensory blocks
At times, damage to other parts of the nervous system, particularly nerves in the head, neck, face and extremities, may cause pain. Blockade of these nerves may provide a clinician with information about whether or not SIP (sympathetically independent pain) is present and can help direct medical treatment. An example is a patient who has CRPS in association with carpal tunnel syndrome caused by compression of the median nerve in the wrist. All the rules about blocks, including the dangers of neuroablative procedures, apply to somatosensory as well as sympathetic nerve blockade.

Surgical nerve decompression
Surgical relief of compressed nerves may provide pain relief in patients with CRPS II. Most experts believe that any surgical procedures in an area of the body affected by CRPS, including those done on or around somatosensory nerves, also require the use of regional sympathetic blockade because CRPS may get worse if such blockade is not part of the surgical plan.

Regional anesthesia blockade
There are a variety of ways to produce regional anesthesia of somatosensory nerves and/or regional sympathetic blockade, including the injection of drugs and/or local anesthetics into veins or into the epidural space of the spine and the use of radiofrequency (RF) or surgical interruption of nerves. These techniques are often used when simpler procedures have failed to produce any lasting relief of symptoms, and should only be done by very qualified specialists (almost always anesthesiologists with special training in pain management). The long-term value of these techniques is unknown and there is considerable differences in availability depending on where you live and in types of procedures used. Neuroablative (permanent) blocks are generally discouraged except in end-of-life care, as discussed above.

Continuous infusion blocks
Something to consider when temporary blocks fail is the continuous infusion of local anesthetics into various parts of the body. This includes areas where nerves may be found together in “nerve plexuses�?or in the epidural space of the spine. There is some evidence for the usefulness of these techniques, but they are usually available only in highly specialized pain treatment centers. When available, they are generally preferred before trying even riskier techniques (to be discussed below).

Neurolytic (neuroablative) blocks
This refers to permanent blocks in portions of the somatosensory or sympathetic nerve system, and has already been discussed in previous sections. Surgical interruption of sympathetic nerves (sympathectomy) was once very popular, but has now fallen out of favor. It is generally agreed that all neurolytic procedures should be limited to end-of-life care; however, it still continues to be a method of treatment in many parts of the world. This may be because of the sense of desperation that CRPS patients may bring to their physicians and the lack of knowledge about poor long-term outcomes with these procedures.

Spinal cord stimulation (SCS)
SCS is one of the more promising techniques available for the treatment of CRPS. Once felt to be only a “last resort�?in treatment (and still considered so by many insurance companies), newer information suggests that when performed by an experienced and specially trained surgeon, SCS can be of considerable help in CRPS. Outcomes vary with the skill and experience of the medical team, and great care should be taken in choosing a practitioner who offers this therapy. SCS is generally first offered on a temporary basis and, if successful, is then used on a more permanent basis through surgery. Risks include equipment failure, infection, and injury to the spinal cord. The long-term (over years) outcomes of SCS await further studies from multiple specialty centers.

Peripheral nerve stimulation (PNS)
Peripheral nerve stimulators have been placed near the spinal cord or further away in the limbs, usually when severe pain is present in the territory (or distribution) of a somatosensory nerve. This may or may not be accompanied by signs of CRPS in more distant areas. PNS is a highly specialized area that is available in few parts of the country and there is limited information about its usefulness.

Intrathecal drug delivery (ITDD)
A variety of drugs have been injected into different parts of the spinal canal for the treatment of severe pain, including pain related to cancer and CRPS. Only morphine is approved by the U.S. Food and Drug Administration for this purpose, but numerous other drugs have been used “off label.�?The technique is most often used in patients who have had good responses to the use of morphine-like drugs (opioids) taken by mouth, who can no longer use them because of intolerable side effects that can develop as tolerance to the pain-relieving effects of the drug occurs and progressively higher doses are required to get the same pain relief. Most specialists believe ITDD to be a truly “last resort�?treatment for CRPS, when all other techniques have failed, because of the high rate of complications, high maintenance costs and general unavailability in the medical community.