Spinal cord stimulation should be considered earlier, rather than a last resort for treating a rare but debilitating chronic pain condition known as complex regional pain syndrome, 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 was moderated by recognised leaders in research and treatment of complex pain. 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 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.
Complex regional pain syndrome has been recognised since the US Civil War. A physician noticed unusual symptoms in soldiers who had suffered nerve injury, and termed the condition causalgia—now known as complex regional pain syndrome type II. Formerly called reflex sympathy dystrophy, complex regional pain syndrome type I is more common and does not have confirmed nerve damage as its cause.
Complex regional pain syndrome occurs about 1% of the time after a fracture or injury, or sometimes due to no obvious cause. Long after the initial injury has healed, in complex regional pain syndrome, pain continues to worsen and may spread. The affected area may swell, undergo colour 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 spinal cord stimulation, 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%, a patient may opt to continue and have a pacemaker-like pulse generator—usually under the skin of his chest, abdomen or buttock—to power the device. Patients receive a hand-held controller to switch between stimulation programmes at home.
To facilitate functional rehabilitation in complex regional pain syndrome, according to an analysis in the March/April issue of Neuromodulation: Technology at the Neural Interface, spinal cord stimulation should be considered as soon as more conservative therapies have failed—after perhaps three months. “Because there is extensive evidence that spinal cord stimulation therapy is effective for the treatment of pain from complex regional pain syndrome and, when compared with medication management, is more cost effective, safer, and cost neutral over time,” Lawrence Poree, Pain Clinic of Monterey Bay, and co-authors wrote, “it is clear to us…that spinal cord stimulation should be used before embarking on long-term opioid/medication management.”
International Neuromodulation Society panelist Marc Russo, who directs the Hunter Pain Clinic in New South Wales and Inpatient Complex Regional Pain Syndrome Management Program at Lindard Private Hospital in Newcastle, Australia, has treated more than 700 complex regional pain syndrome patients. He agrees that there is no evidence to support opioid administration in complex regional pain syndrome, 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 complex regional pain syndrome, many doctors are now using that in patients after trauma or before peripheral limb surgery.
• For complex regional pain syndrome patients referred to spinal cord stimulation, a relatively long stimulation trial of seven to 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 complex regional pain syndrome 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 complex regional pain syndrome, 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 intravenous treatment with bisphosphonate, a class of drugs with the potential to reduce pain associated with patchy bone demineralisation.
• The use of sympathetic nerve blocks, intravenous regional anaesthesia, ketamine infusions and traditional physical therapy also may help, although the evidence for these is less strong, or conflicting.
• Once complex regional pain syndrome has continued, there is evidence for use of spinal cord stimulation—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% of advanced cases of complex regional pain syndrome.
• Clinical studies show that the benefits of spinal cord stimulation in complex regional pain syndrome 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 spinal cord stimulation trial as an adjunctive complex regional pain syndrome treatment. Future availability of affordable spinal cord stimulation systems with a moderate battery capacity of two years could facilitate that.
• After two or more years of spinal cord stimulation without complex regional pain syndrome symptoms, the physician may choose to remove the system.
Since more than one mechanism goes awry in complex regional pain syndrome, it may be that neuromodulation effectively treats persistent effects of complex regional pain syndrome type I because it is a multimechanism therapy, remarked Frank Huygen, professor of Pain Medicine, and head of the Center for Pain Medicine, Erasmus University Medical Centre, Rotterdam, The Netherlands. An internationally recognised complex regional pain syndrome researcher, he co moderated the International Neuromodulation Society expert panel discussion and served on the International Neuromodulation Society scientific congress faculty. He suggested that spinal cord stimulation probably has a dual effect in complex regional pain syndrome by addressing neuropathic pain as well as helping normalise aberrant microcirculation that is associated with swelling, skin discolouration, temperature changes and related complaints.
While a number of medications and strategies can be employed to treat various facets of complex regional pain syndrome, Huygen added, his centre routinely has complex regional pain syndrome patients undergo a programme 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 centralising complex regional pain syndrome treatment in special clinics, to increase numbers needed for research and secondly to look at more international collaborations,” he commented about when to offer spinal cord stimulation during treatment for complex regional pain syndrome. “The world is small enough…why not an international attempt to resolve this important question and others?”
