Complex regional pain syndrome (formerly called reflex sympathetic dystrophy) is a rare disorder of the extremities characterized by autonomic and vasomotor instability.

The cardinal symptoms and signs are pain localized to an arm or leg, swelling of the involved extremity, disturbances of color and temperature in the affected limb, dystrophic changes in the overlying skin and nails, and limited range of motion.

Strikingly, the findings are not limited to the distribution of a single peripheral nerve.

Most cases are preceded by surgery or direct physical trauma, often of a relatively minor nature, to the soft tissues, bone, or nerve.

Early mobilization after injury or surgery reduces the likelihood of developing the syndrome.

Any extremity can be involved, but the syndrome most commonly occurs in the hand and is associated with ipsilateral restriction of shoulder motion (“shoulder-hand” syndrome).

This syndrome proceeds through phases: pain, swelling, and skin color and temperature changes develop early and, if untreated, lead to atrophy and dystrophy.

The swelling in complex regional pain syndrome is diffuse (“catcher’s mitt hand”) and not restricted to joints.

Pain is often burning in quality, intense, and often greatly worsened by minimal stimuli such as light touch.

The shoulder-hand variant of this disorder sometimes complicates MI or injuries to the neck or shoulder.

Complex regional pain syndrome may occur after a knee injury or after arthroscopic knee surgery.

There are no systemic symptoms.

In the early phases of the syndrome, bone scans are sensitive, showing diffuse increased uptake in the affected extremity; radiographs eventually reveal severe generalized osteopenia.

This syndrome should be differentiated from other rheumatoid arthritis, thoracic outlet obstruction, and mononeuritis multiplex, among others.

Early treatment offers the best prognosis for recovery.

For mild cases, NSAIDs (e.g., naproxen 250–500 mg bid po) can be effective.

For more severe cases associated with edema, prednisone, 30–60 mg/day orally for 2 weeks and then tapered over 2 weeks, can be effective.

Pain management is important and allows for effective physical therapy, which is critical to restore function.

Some patients may benefit from antidepressant agents (e.g., nortriptyline initiated at a dosage of 10 mg po at bedtime and gradually increased to 40–75 mg at bedtime) or anticonvulsants (e.g., gabapentin 300 mg tid po).

Bisphosphonates, calcitonin, regional nerve blocks, and dorsal-column stimulation have also been reported to be helpful.

Vitamin C supplementation (1 g po od) may have a role in preventing the development of complex regional pain syndrome following surgical procedures known to be a risk factor (e.g., total knee replacement, foot or ankle surgery).

The prognosis partly depends on the stage in which the lesions are encountered and the extent and severity of associated organic disease.

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