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Systematic review of intravenous regional sympathectomy for reflex sympathetic dystrophy

Chronic non-malignant pain is often difficult to treat, and performing randomised controlled trials (RCTs) in persons with these pains raises many practical and ethical problems. A major difficulty is the high placebo response rates often found by RCTs - which is why placebo-controlled trials are necessary in these conditions.

Over 120 years ago a syndrome of persistent burning pain and trophic changes called causalgia was noted in the limbs of soldiers after gunshot wounds. The term reflex sympathetic dystrophy (RSD) is now used to describe a number of chronic pain conditions associated with altered activity of the sympathetic nervous system. RSD may be the extreme end of a spectrum of conditions associated with damage to nerves after trauma.

The clinical reality is a "funny pain" in a "funny looking" limb. The diagnosis suggests that a disordered nervous system causes the pain - but it may be that the pain causes a disordered nervous system.

How common is RSD?

The incidence of RSD among patients in a tertiary referral centre is about 2 - 5%. In the general population the incidence is of the order of 10 per million population.

How is RSD treated?

A common treatment is intravenous regional sympathetic blockade (IRSB). This involved injecting a high concentration of a drug known to block the sympathetic nervous system (guanethidine in the original report) into a limb isolated with a tourniquet.

Does ISRB work?

There have been few RCTs. Those that have been done have been collected into a systematic review together with a new RCT [1]. There were seven controlled trials with guanethidine, reserpine, bretylium, droperidol or ketanserin. Sample sizes ranged from six to 21 patients.

Five of the seven RCTs in the systematic review failed to show a significant analgesic difference between the ISRB and control groups. The new RCT in the paper was stopped early because of a significant incidence of severe adverse effects. The analysis did not show any analgesic effect of IRSB.

Should IRSB be bought by purchasers?

Almost certainly not. This is a complicated subject with many nuances, but the collected evidence indicates that the procedure is without significant analgesic effect but with potentially dangerous adverse effects.

That does not mean that there is not a research agenda. Patients with RSD have few effective treatment options, and it may be that there are elements in the procedure - perhaps the tourniquet itself in some patients - which could provide relief. We need to know what they are.

Reference:

1: AR Jadad, D Carroll, CJ Glynn, HJ McQuay. Intravenous regional sympathetic blockade for pain relief in reflex sympathetic dystrophy: a systematic review and a randomised, double-blind crossover study. Journal of Pain and Symptom Management 1995 10: 13-20.



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