Pseudodystrophy. A conversion disorder mimicking reflex sympathetic dystrophy.

The authors suggest some criteria by which pseudodystrophy and reflex sympathetic dystrophy, although sharing some similar clinical features, can be distinguished as two different conditions, each requiring its own approach and management. The most important distinction is found on bone scintigraphy. In reflex sympathetic dystrophy the bone scan shows a typical increased tracer uptake (at least during stages I and II); in pseudodystrophy there is a normal or decreased tracer uptake in the affected region. Moreover the vascularization is increased in reflex sympathetic dystrophy stage I, whereas in pseudodystrophy hypovascularization is found from the beginning. The clinical features, as well as the results of technical investigations, psychological evaluation and treatment of 4 patients with pseudodystrophy are presented. The importance of distinguishing this condition from reflex sympathetic dystrophy is stressed.