bone scanning should be performed because of the possible coexistence of asymptomatic AVN, as commonly occurs in organ transplant patients; radiophosphate imaging facilitates a total body search. Asymptomatic lesions are known to resolve without ever producing changes on the plain radiograph.

Reflex sympathetic dystrophy

There is a broad group of clinical conditions in which pain and autonomic dysfunction are closely related. Similarities between transient osteoporosis of the hip, regional migratory osteoporosis and reflex sympathetic dystrophy (RSD) attest to this observation, and they may represent different aspects of a single syndrome. RSD can follow trauma, surgical treatment, nonsurgical treatment or occur for no obvious reason. It is known under many descriptive names, reflecting the predominant signs, symptomatology and location as in causalgia, acute atrophy of bone, Sudeck's atrophy, peripheral acute trophoneurosis, posttraumatic angiospasm, posttraumatic edema, shoulder-hand syndrome, reflex algodystrophy and algoneurodystrophy. Signs and symptoms include pain, hyperesthesia, swelling, stiffness, hyperhidrosis and discoloration of the skin ranging from red to grayish blue, or a mixture of the two extremes. In the absence of remission, dermal atrophy and contractions may occur.

In adults, the three-phase radiophosphate portrayal in the acute stage is that of increased perfusion, blood pool activity, and uptake in the delayed static images, best appreciated in juxtaarticular bone. All three phases must be diffusely increased to all portions of the wrist and hand or the entire foot (Fig. 9). Plain radiographs depict mineral depletion, but its appearance is often antedated by the radionuclide abnormalities. With clinical remission, the enhanced perfusion and blood pool activity are the first to recede toward normal while uptake on the delayed image is the last to normalize. If the disorder proceeds to an atrophic fibrous stage, each of the phases

Figure 9. Acute reflex sympathetic dystrophy. Three-phase bone study showing perfusion, blood pool (1 minute) and delayed image (3 hours). There is increased activity in all phases on the right side.
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