Reflex sympathetic dystrophy (Sudeck's osteodystrophy)

Reflex sympathetic dystrophy:

A constellation of changes involving the sympathetic nervous system, which has been known under many names (causalgia, Sudeck's osteodystrophy, posttraumatic osteoporosis, algodystrophy, shoulder hand syndrome). This syndrome can be precipitated by any neurally related visceral, musculoskeletal, neurologic or vascular condition. Frequently, however, a cause is not identifiable. Trauma, cerebrovascular disorders, degenerative disease of the cervical spine, discal herniation, postinfectious states, calcific tendinitis, vasculitis and neoplasm have all been associated with reflex sympathetic dystrophy.
Various theories have been advanced to explain the pathogenesis; the most widely held explanation involves the existence of an "internuncial pool." In this theory an injury or lesion is assumed to produce painful impulses that travel via afferent pathways to the spinal cord, where a series of reflexes are initiated that spread via the interconnecting pool of neurons. The lateral and anterior tracts are stimulated, which provokes efferent pathways to the peripheral nerves, producing the local findings of reflex sympathetic dystrophy.

Patients may exhibit variable symptoms and signs, often in the shoulder and hand. Stiffness, pain, tenderness and weakness may be associated with swelling, vasomotor changes, hyperaesthesia and disability. Glenohumeral joint periarthritis may be accompanied by a shoulder hand syndrome.

Radiographically, soft tissue swelling and regional osteoporosis are the most important features (Fig.1). Metaphyseal bone resorption leads to periarticular osteoporosis; subperiosteal bone resorption resembles that seen in patients with hyperparathyroidism; intracortical bone resorption produces excessive striation or tunnelling in cortices; endosteal bone resorption causes initial scalloping of the endosteal surface, with subsequent widening of the medullary canal; and subchondral and juxta-articular erosion may lead to small periarticular erosions. The extensive involvement and the severity of the bone resorption may lead to the radiographic appearance of rapid and severe osteopenia. However, the preservation of the joint space in this syndrome cannot be overemphasized as a characteristic feature of reflex sympathetic dystrophy

Scintigraphy of the bones and joints also shows increased accumulation of radionuclide agents in joints and bones, which may be related to an increased blood flow. Although the disease is bilateral, the abnormalities are much more marked on one side than on the other. Some patients reveal a segmental pattern affecting only a portion of an extremity.