Oral phentolamine mesylate in the treatment of complex regional pain syndrome.

Complex Regional Pain Syndrome (previously known as reflex sympathetic dystrophy, RSD) is a condition presenting with burning, nondermatomal pain associated with hyperhidrosis, intermittent oedema and discolouration and with evidence of mechanical and thermal allodynia. Conventional treatment is with sympathetic blockade produced by local anaesthetic injection around the appropriate sympathetic ganglia or by the use of agents depleting the sympathetic nerve endings ofnoradrenaline (eg intravenous regional sympathetic block with guanethidine). In a relatively small percentage of cases treatment is not effective. Phentolamine mesylate has been shown to be useful in diagnosing pains with a sympathetic component' but to date this has not been used for treatment by the oral route for this condition.