Treatment of Reflex Sympathetic Dystrophy

Interventional Procedures for Reflex Sympathetic Dystrophy

Interventional therapies have been commonly used in the treatment of reflex sympathetic dystrophy (RSD) even though there was little scientific evidence of their efficacy. The basic premise of most interventional treatments is the involvement of the sympathetic nervous system in RSD, a premise which has come under increasing scrutiny in the face of new evidence of more global involvement.

The role of interventional treatment in RSD is that of an adjunct therapy performed in order to provide pain relief to enable the patient to actively participate in functional rehabilitation. The decision to undergo interventional therapy should be considered carefully regarding the level of need, timing, and whether it will be more effective for pain relief than other therapies which had been undertaken and failed.

Interventional procedures include:

• Nerve block
• Sympathectomy
• Spinal Cord/Peripheral Nerve Stimulation
• Implantable Spinal Pumps

You can read more about various interventional procedures by clicking on the following link: http://www.ncbi.nlm.nih.gov/pubmed/16772798

Nerve Block

A nerve blockade is a procedure usually performed by a pain management specialist (anesthesiologist) and its objective is to interrupt the flow of pain signals along the sympathetic nerve in the region of RSD pain. If successful, the anesthetic temporarily blocks the local sympathetic nervous system and thus reduces or eliminates pain.

Based on clinical experience, some doctors recommend a nerve block in the presence of any of the following conditions:

• Burning pain
• Allodynia (pain in response to innocuous stimuli such as a feather touch or breeze on the limb)
• Temperature changes in the affected limb
• Color changes in the affected limb
• If pain is limiting functional rehabilitation early in the treatment process with physical therapy or occupational therapy despite medication

There are three types of nerve blocks - two that target the sympathetic nervous system and one that targets the local nerves in the affected limb. These include:

• Stellate ganglion block - the anesthetic is injected around the sympathetic nerves in the cervical spine area to interrupt pain signals to the upper body and arm.

• Lumbar sympathetic block - the anesthetic is injected around the sympathetic nerves in the lumbar region and targets interruption of nerve signals causing lower body/leg pain.

• Bier block - also called Intravenous Regional Anesthesia block (IVRA). With this procedure, blood is drained from the limb either by gravity (holding the limb up) or pressure. A blood pressure cuff is then inflated at the upper arm or leg and an anesthetic is injected intravenously into a blood vessel in the hand or foot. The inflated cuff prevents the anesthetic from flowing out of the limb and into the body. The patient may feel a burning sensation and numbness as the anesthetic diffuses from the blood vessels into nearby nerves. The procedure ends by slowly deflating the pressure cuff allowing the small amount of residual anesthetic to slowly flow out of the limb through the veins into the body where it is resorbed. The numbness eventually wears off. Pain relief is temporary and may last days, weeks, or months. When the effect wears off, the procedure can be repeated. The main complication of the Bier block is that if the pressure cuff is released too quickly, before a sufficient amount of anesthetic has been absorbed into the arm, too much anesthetic is introduced into the body and can reach toxic levels.

Until recently, sympathetic nerve block played an important role in the diagnosis and treatment of RSD. If a sympathetic nerve block was performed on a patient and there was relief from pain, the diagnosis of RSD was confirmed. Currently, however, since there is ongoing debate over the exclusive role of the sympathetic nervous system in RSD, it plays a less prominent role now in RSD, although it is still performed often. There are few rigorous studies on any of these nerve blocks in RSD and data is unclear regarding long-term efficacy.

If the sympathetic nerve block is effective, it usually provides immediate, although temporary, pain relief and also increases the patient's level of comfort and function. This provides the patient with a window of opportunity for more intense efforts to restore function with increased physical therapy. In addition, this procedure does not interfere with motor activity so the patient can remain mobile and active after nerve block administration. Recurrence of pain after the initial nerve block occurs in many patients and subsequent sympathetic nerve blocks or stronger measures are required.

Despite popular opinion, there is little evidence-based information regarding the best timing for administering nerve blocks, the number that should be administered, or its long-term efficacy. In any event, nerve blockade should always be accompanied by aggressive physical rehabilitation. Because a variety of complications can occur following a nerve block, it is prudent for patients to select a pain management specialist, such as an anesthesiologist, who is experienced with this technique.

Potential complications that may result from sympathetic nerve blocks include:

• Nerve injury
• Bleeding - nerve blocks are usually contraindicated in patients who are taking anticoagulant medications
• Allergic reactions - nerve blocks with local anesthetics are contraindicated in patients who are allergic to these medications
• Psychological reactions - anxiety and fear related to apprehension about the nerve block procedure

There are no universally accepted guidelines regarding the choice of anesthetic for the blockade, which patients benefit the most from the blockade, and which type of nerve block is most effective. The most commonly used anesthetic is lidocaine.

Sympathectomy

Sympathectomy is a procedure that is intended to destroy the collection of sympathetic nerve cells (sympathetic ganglion) along the spinal cord and to suppress or block the sympathetically-maintained pain in the affected area. Because a sympathectomy is a procedure that carries significant risks (which will be discussed below) and the outcome may vary from patient to patient, the decision to undergo this procedure should be carefully assessed. Patients who are offered a surgical sympathectomy as a treatment option for their RSD pain should carefully find out about the surgeon's experience and success rate with this procedure before undergoing the procedure.

Patients are considered as potential candidates for sympathectomy only if response to a sympathetic nerve block shows that the source of the RSD pain is sympathetically-maintained pain. If the source of the RSD pain is determined to be sympathetically-independent pain (i.e., no reduction of pain is noted after a nerve block), a sympathectomy is not a viable treatment option.

There are 2 types of sympathectomy:

• Chemical sympathectomy
• Surgical sympathectomy

Chemical Sympathectomy

During a chemical sympathectomy, a neurolytic agent (a chemical that destroys nerve cells) is injected into the sympathetic ganglion at a specific site to block sympathetically-maintained pain. Phenol and ethanol are the two most frequently used neurolytic agents for chemical sympathectomy.

Potential complications of chemical sympathectomy include:

• Post sympathectomy pain
• Paralysis
• Neuritis - inflammation of a nerve due to irritation from the phenol or ethanol

Surgical Sympathectomy

A surgical sympathectomy involves cutting and cauterizing (sealing) the nerves of the sympathetic ganglion at a specific location along the spinal cord. There are various techniques that may be used to perform a surgical sympathectomy, including video-assisted surgery, open surgery, or radiofrequency sympathectomy.

Following a surgical sympathectomy, the patient may experience complete pain relief, partial pain relief, or no pain relief. In general, many patients experience complete or partial pain relief for several months following a surgical sympathectomy but only about 15% to 30% experience long-term relief lasting two years or longer.

In a study published in 2002 in the Journal of Vascular Surgery, researchers from the University of South Florida College of Medicine reported that approximately 90% of patients with RSD in their study who underwent surgical sympathectomy reported at least a 50% reduction in pain intensity, although the level of pain reduction deteriorated over time. Ten percent of the patients in this study were considered treatment failures. A significant subset of the total patients regretted having undergone the procedure due to subsequent reported high levels of disability. Overall patient satisfaction was 77%.

You can read more about this study by clicking on the following link: http://www.ncbi.nlm.nih.gov/pubmed/11854724

Potential complications of surgical sympathectomy include:

• Post-sympathectomy pain - pain associated with the surgical procedure which has been reported to occur in about 40% of patients
• Compensatory hyperhidrosis - excessive sweating of the face, trunk, or legs
• Recurrence of RSD pain
• Pneumothorax - accidental injury to the lung (for upper body RSD)
• Horner's syndrome - a syndrome caused by injury to the sympathetic nerves of the face which includes a constricted pupil, drooping eyelids, and facial dryness
• Reduced blood pressure when standing (postural hypotension)

Generally, there is debate about this procedure in the medical community for several reasons, including:

• Significant complications
• Procedure does not sufficiently enhance the effectiveness of physical or occupational therapy
• Lack of well designed randomized controlled clinical trials proving efficacy of this procedure
• Key role of the sympathetic nervous system in RSD is being increasingly challenged

Spinal Cord Stimulation

Another treatment option for patients with RSD is the use of electrical nerve stimulators that apply a small amount of electrical current to the nerves to overcome the sensation of pain. This type of treatment is known as spinal cord stimulation (SCS).

A spinal cord stimulator is a device that consists of a power source, leads (wires), and an external controller. A small wire, called a lead, is surgically implanted into the epidural space of the spinal column and is connected to a power source and an external unit controlled by the patient. When the patient initiates the flow of electrical current from the external unit, low-level electrical impulses are transmitted through the lead wire to the spinal cord to interrupt and block pain. Spinal cord stimulation affects the entire central nervous system. Peripheral nerve stimulators (PNS) are similar to spinal cord stimulators with the difference being that the electrodes are placed outside the central nervous system and they target only the peripheral nervous system.

In most cases, before a spinal cord stimulator is implanted permanently, a temporary stimulator is implanted for a trial period of several days to determine if the patient will experience a reduction in the level of pain. If good pain control is achieved during the trial period, the next step is the surgical implantation of a permanent spinal cord stimulator. Patients with implanted device often describe the sensation of the electrical current from the SCS as a "tingling" feeling, however, these sensations are far less bothersome compared to the pain associated with RSD.

There is no consensus regarding the timing of the initiation of SCS in the rehabilitation process of RSD. In 2002, an expert panel at the Cleveland Clinic Foundation published treatment guidelines in Pain Practice. In the guidelines, the panel recommended that interventional therapies such as SCS should be considered at early stages of therapy for some cases of RSD if it will help with advancing rehabilitation. It cannot be argued that the patient should have tried all conservative therapies before considering SCS and they should not have to wait as long as previously thought before being offered SCS as an option. In short, SCS should no longer be considered a last-resort treatment modality.

For more information about the report of this expert panel, please click on the following link: http://www.ncbi.nlm.nih.gov/pubmed/17134466

Spinal cord stimulators enable patients suffering from chronic RSD pain a means of better controlling their pain. Patients are usually able to resume their normal activities both at home and at work and also participate in recreational activities since the unit is portable. Although SCS is not a cure for chronic RSD pain, in many cases it can reduce the level of intensity of the pain and make it more manageable.

There are reports that many patients who undergo this procedure report a 50-70% reduction in pain or at least enough to become functional at work or lead an active life. A meta-analysis of the efficacy of spinal cord stimulation for RSD showed that it reduces pain, improves quality of life, enables some patients to return to work, and reduces the amount of medication taken by some patients.

To read more about this interesting finding, please click on the following link: http://www.ncbi.nlm.nih.gov/pubmed/16647590

Though some patients report successful control of pain in studies involving SCS compared to placebo groups, there is currently no absolute proof of efficacy. There is some indication that SCS may be effective in patients who have already undergone surgical sympathectomy. In addition, there are indications that a patient's positive response to a prior sympathetic nerve block may predict a good response to SCS. Spinal cord stimulation seems to produce analgesia without any reduction of sympathetic function.

Patients with RSD who may be considered as candidates for SCS include:

• Patients not making significant progress in rehabilitation with conservative therapy who will be able to exercise more effectively and participate in a more intensive rehabilitation protocol with increased control over pain
• Patients who are psychologically stable and have realistic expectations regarding further treatment and prognosis
• Patients who have had a favorable response to sympathetic nerve blocks but need more intense pain relief

If the patient is deemed a candidate for SCS, it is important to perform the procedure in a timely manner since waiting too long may diminish the success of the treatment.

Potential risks and complications associated with surgical implantation of the spinal cord stimulator include:

• Infection
• Headache
• Bleeding
• Spinal cord injury
• Failure to relieve pain
• Pain at the site of the implant
• Hardware malfunction

Contraindications to the use of SCS include:

• Patients with implantable devices such as a pacemaker or defibrillator
• Patients undergoing radiation therapy
• Patients who are exposed to detection equipment devices including anti-theft devices, security devices, and aircraft communication systems

Patients who have an implanted SCS device should not drive or operate heavy equipment while the device is activated. They should also carry special identification papers through security systems (such as airports) since the system can activate metal detectors.

Since being introduced in the 1960s, spinal cord stimulation fell out of favor but with recent advances in technology, it is being re-evaluated for its efficacy in treating chronic pain. Data is limited but there is evidence of efficacy of spinal cord stimulation. In 2000, a study was published in the New England Journal of Medicine and reported that a group of patients with RSD who had been treated with SCS and physical therapy experienced significant reduction of pain and increased quality of life compared to a group that was given physical therapy alone. Functional outcome in terms of day to day use of the affected limb, however, was no better than the group who had received physical therapy alone.

To read more about this please click on the following link: http://www.ncbi.nlm.nih.gov/pubmed/10965008

Spinal cord stimulation has been approved by the US Food and Drug Administration (FDA) as a treatment for RSD. The FDA approved the ANS Renew and the Medtronics Mattrix systems for SCS delivery.

Implantable Spinal Pumps

Implantable spinal pumps provide a way of delivering drugs intrathecally, the administration of drugs directly into the spinal fluid. Medications are delivered within the intrathecal space (the space surrounding the spinal cord) by either injection through a needle or via a catheter that is connected to a pump. Doses can be programmed to be delivered continuously at a particular rate which can be increased or decreased, or on a schedule controlled by the patient. Medications can be opioid or non-opioid but morphine is the "gold standard" drug used in the implantable spinal pump. If the patient cannot tolerate morphine, other drugs such as baclofen or ziconitide may be tried. Long-term experience with the morphine pump in patients with chronic pain, including those with RSD, indicates few advantages over oral morphine administration. In fact, many patients with implantable morphine pumps also require oral morphine supplementation to control their pain. The implantation of a morphine pump is also associated with potential complications including:

• Infection
• Bleeding
• Spinal fluid leaks
• Injury to the spinal cord
• Malfunction of the pump

Side effects of morphine include:

• Nausea/vomiting
• Urine retention
• Itching
• Constipation
• Confusion
• Sexual dysfunction

Implantable spinal pumps are considered a last resort therapy and should be only considered if the patient doesn't respond to spinal cord stimulation or has multiple pain sites. Before a patient can be considered for intrathecal medication, it is important to evaluate several factors such as:

• If the patient has had any adverse response to any systemic medications
• If the patient is motivated to pursue functional rehabilitation when they experience symptom relief from the implantable pump
• If the patient is psychologically stable and can control their medications in an appropriate manner
• If the patient understands the risks and benefits of this therapy
• How the patient has responded to all previous treatments

Implantable spinal pump is contraindicated in the following conditions:

• If the patient is intolerant to the medications used in the pump
• If the patient has an infection
• If the patient has problems with blood clotting