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Acute Pain | Chronic Pain | General

Intravenous regional sympathetic blockade (IRSB) for reflex sympathetic dystrophy (Complex Regional Pain Syndrome)

Clinical bottom line:

There is no evidence from existing trials that guanethidine used in intravenous regional sympathetic blockade reduces the pain associated with reflex sympathetic dystrophy. Based on a small number of patients, there is weak evidence that ketanserin and bretylium may provide some relief.

Reflex sympathetic dystrophy or Complex Regional Pain Syndrome (CPRS) describes the constellation of chronic pain conditions associated with hyperactivity of the sympathetic nervous system. Pain is usually constant, severe and unresponsive to conventional analgesics. Intravenous regional sympathetic blockade (IRSB) is an intervention where a drug known to block the sympathetic nervous system is given in high local concentration in the painful limb isolated with a tourniquet.

Systematic review

Jadad, A. R, Carroll, D, Glynn, C. J, McQuay, H. J. Intravenous regional sympathetic blockade for pain relief in reflex sympathetic dystrophy: a systematic review and a randomized, double-blind crossover study. Journal of Pain and Symptom Management. 1995; 10(1): 13-20.

Inclusion criteria were trials of patients with chronic pain associated with reflex sympathetic dystrophy; randomised and/or double-blind; administration of an IRSB to at least one of the treatment groups.

Data pooling was not possible. Original trial findings were used as outcomes.


Eight trials were included. Most used guanethidine as the active substance, but reserpine, bretylium, droperidol and ketanserin were used as alternatives. Active controls were bupivacaine, lignocaine or stellate ganglion block.

Two of eight trials (17 patients in total) showed some advantage of IRSB over control. One trial compared ketanserin with placebo, and the other compared bretylium with lignocaine.

Adverse effects

In at least one trial a number of patients suffered from hypotension. Results from other trials were not reported.