As anyone with Complex Regional Pain Syndrome (formerly called Reflex Sympathetic Dystrophy or causalgia) knows, it's very difficult to find any kind of treatment that is effective in relieving the intense pain.
However, a new study published in the Annals of Internal Medicine may have unlocked a key to reducing the pain of CRPS and possibly even other chronic pain conditions.
Researchers at the University of Liverpool noted evidence of immune activaton in the affected limb, peripheral blood, and cerebrospinal fluid of CRPS patients.
From this they theorized that modulating the immune system may result in reduced pain.
To test their hypothesis, the scientists conducted a randomized, placebo-controlled, double-blind study to ealuate the efficacy of treating CRPS patients with intravenous immunoglobin (IVIG).
They found that low-dose IVIG reduced the pain intensity by 30 percent or more for approximately half of the participants.
This study involved 13 patients who had had CRPS for six to 30 months.
All of the participants were required to have previously tried acetaminophen, nonsteroidal anti-inflammatory medications, opioid pain relievers, tricyclic antidepressants, gabapentin or pregabalin, and physiotherapy with unsatisfactory results.
Prior to beginning the study, all of the patients reported a consistent pain intensity of five or higher (on the traditional 0 - 10 pain scale).
Participants were divided into two groups.
One group received the intravenous immunoglobin and the other received a placebo of intravenous saline.
Then, following a 28-day washout period, each group received another IV containing the opposite solution.
The dosage of immunoglobin was 0.25 g/kg per day for two consecutive days.
Patients kept pain diaries, recording their pain levels daily during the study period.
Following the IVIG treatments, pain scores were reduced by an average of 1.55 points.
Five patients reported pain scores at least two points lower and three of them said their pain was reduced by more than 50 percent.
The pain relief lasted for an average of five weeks.
There were no serious adverse reactions reported.
Andreas Goebel, MD, PhD, lead researcher and Senior Lecturer in Pain Medicine, explains: "In CRPS, the real effect of this treatment in clinic may turn out to be even greater than what we have already seen, because IVIG can be given in higher doses, and repeated treatment may have additional effects. IVIG is normally repeated every four weeks and we are working to develop ways which would allow patients to administer the treatment in their own home.
"The discovery is expected to have a real impact on the treatment of other unexplained chronic pain conditions; if one pain condition can be effectively treated with an immune drug, then it is possible that other types will also respond."
Goebel , A, et al. (2010). Intravenous immunoglobulin treatment of the complex regional pain syndrome: a randomized trial. Annals of Internal Medicine, 152(3), 152-158.