Newswise — Spinal cord stimulation should be considered earlier than a last resort for treating a rare but debilitating chronic pain condition known as complex regional pain syndrome (CRPS), according to a research analysis in Neuromodulation: Technology at the Neural Interface, the journal of the International Neuromodulation Society.

Members held an online discussion about the topic in July during one of the society’s periodic Expert Panels. The discussion July 7 – 21 was moderated by recognized leaders in research and treatment of CRPS. The interactive session took place shortly after the society’s 11th biennial World Congress Berlin in June, where some 1,400 delegates addressed the full range of neuromodulation therapies for chronic pain, movement disorder, and emerging indications.

Spinal cord stimulation (SCS) to treat chronic neuropathic pain of the trunk and limbs has been FDA-approved since 1989, and word about the option is growing among patients, referring physicians, and allied health professionals. CRPS patients such as Ed Levien of Bethesda, MD are trying to raise more awareness about treatment options for chronic pain. He only learned about SCS through another patient, 12 years after suffering an injury that triggered pain so severe he could not tolerate anything touching his affected arm.

Complex regional pain syndrome (CRPS) has been recognized since the U.S. Civil War. A physician noticed unusual symptoms in soldiers who had suffered nerve injury, and termed the condition causalgia – now known as CRPS Type II. Formerly called Reflex Sympathy Dystrophy, CRPS Type I is more common and does not have confirmed nerve damage as its cause.

CRPS occurs about 1 percent of the time after a fracture or injury, or sometimes due to no obvious cause. Long after the initial injury has healed, in CRPS, pain continues to worsen and may spread. The affected area may swell, undergo color or temperature changes, experience tremors or lack of coordination, and become hypersensitive to touch. If the condition does not reverse with early intervention and frequent follow-up, it can become extremely disabling and lead to muscle atrophy and loss of function. While some cases may go into remission, there is no definitive cure and the condition can be difficult to treat.

In SCS, a slender electrical lead is implanted under the skin of the back to deliver a mild electrical current to the spinal cord. If trial stimulation reduces chronic pain by at least 50 percent, a patient may opt to continue and have a pacemaker-like pulse generator implanted – usually under the skin of his chest, abdomen or buttock— to power the device. Patients receive a hand-held controller to switch between stimulation programs at home.

Levien said the effect of SCS was noticeable right away when his device was switched on, and full benefits felt within weeks. He credits SCS with giving him his life back – so he could move again, use his dominant arm, enjoy everyday activities and hobbies, and resume productive work. Prior to SCS, he said, on his worst days, the pain was so severe that even breathing was a chore. He spent more than one year in physical therapy and now works with a trainer at a gym, hoping to one day return to sports such as tennis. Interestingly, he said, he noticed he keeps reducing the power, and when he is working at the gym, he only feels arm strain on the side that does not receive SCS stimulation.

To facilitate functional rehabilitation in CRPS, according to an analysis in the March/April issue of Neuromodulation: Technology at the Neural Interface, SCS should be considered as soon as more conservative therapies have failed – after perhaps three months. “Because there is extensive evidence that SCS therapy is effective for the treatment of pain from CRPS and, when compared with medication management, is more cost effective, safer, and cost neutral over time,” write Lawrence Poree M.D., M.P.H., Ph.D., of the Pain Clinic of Monterey Bay, and co-authors, “it is clear to us . . . that SCS should be used before embarking on long-term opioid/medication management.”

INS Expert Panelist Dr. Marc Russo, who directs the Hunter Pain Clinic in New South Wales and Inpatient CRPS Management Program at Lindard Private Hospital in Newcastle, Australia, has treated more than 700 CRPS patients. He agrees there is no evidence to support opioid administration in CRPS, and in his experience, intrathecal opioids tend to make CRPS patients worse over the long term.

Several steps can be taken, however:

• With good evidence that a course of Vitamin C at 500 mg/day in adults for six weeks after wrist trauma helps to prevent development of CRPS, many doctors are now using that in patients after trauma or before peripheral limb surgery.

• For CRPS patients referred to SCS, a relatively long stimulation trial of 7 – 30 days, with assessment for both pain and functional outcomes, is advisable to capture an accurate response.

• Referring doctors who are among the first to assess patients need to improve their skills in diagnosing this complex condition, and rapid response referral networks established, so that CRPS can be treated early – rather than after several months – in multidisciplinary settings with pain specialists.

• Although treatment must be tailored to the patient, during the acute phase of CRPS, there is good evidence within the first six months for doctors to consider a six-week course of oral steroids, and also for a single IV treatment with bisphosphonate, a class of drugs with the potential to reduce pain associated with patchy bone demineralization.

• The use of sympathetic nerve blocks, intravenous regional anesthesia, ketamine infusions and traditional physical therapy also may help, although the evidence for these is less strong, or conflicting.

• Once CRPS has continued, there is evidence for use of SCS – with ongoing effectiveness aided by switching between some six different stimulation programs during a week – and possibly for intrathecal baclofen, an anti-spasm agent, to treat dystonia (involuntary flexing) that develops in about 20 percent of advanced cases of CRPS.

• Clinical studies show that the benefits of SCS in CRPS and chronic post-surgical back pain (failed back surgery syndrome) diminish the longer the treatment is delayed; a finding that encourages practitioners to weigh the advantages of considering an early SCS trial as an adjunctive CRPS treatment. Future availability of affordable SCS systems with a moderate battery capacity of two years could facilitate that.

• After two or more years of SCS without CRPS symptoms, the physician may choose to remove the system.

Since more than one mechanism goes awry in CRPS, it may be that neuromodulation effectively treats persistent effects of CRPS Type I because it is a multi-mechanism therapy, remarked Dr. Frank Huygen, professor of Pain Medicine and head of the Center for Pain Medicine at Erasmus University Medical Centre in Rotterdam. An internationally recognized CRPS researcher, he co-moderated the INS Expert Panel discussion and served on the INS scientific congress faculty. He suggested that SCS probably has a dual effect in CRPS by addressing neuropathic pain as well as helping normalize aberrant microcirculation that is associated with swelling, skin discoloration, temperature changes and related complaints.

While a number of medications and strategies can be employed to treat various facets of CRPS, Huygen added, his center routinely has CRPS patients undergo a program of active joint movement and muscle stretching to help reset changes in neural pathways caused by the condition.

“I think we really have to think about more centralizing CRPS treatment in special clinics, to increase numbers needed for research and secondly to look at more international collaborations,” he commented about when to offer SCS during treatment for CRPS. “The world is small enough . . . Why not an international attempt to resolve this important question and others?”

Journal Link: Neuromodulation: Technology at the Neural Interface, March/April 2013