Reflex Sympathetic DystrophyDz

ICD-9 Code: 733.7.

Synonyms: Shoulder-hand syndrome, Sudeck’s atrophy, algodystrophy, causalgia.

Definition: Reflex sympathetic dystrophy is diffuse persistent pain, usually in an extremity, often associated with vasomotor disturbances, trophic changes, and limitation or immobility of joints. Causalgia, a different syndrome, refers to a traumatized peripheral nerve with resultant pain along the distribution of that nerve.

Etiology: Many diseases have been associated with reflex sympathetic dystrophy: trauma, fractures (especially Colles fracture), hemiplegia (prevalence of reflex sympathetic dystrophy 12%–21%), arterial thrombosis, peripheral nerve injury (3%), acute coronary artery disease (5%–20%), painful rotator cuff lesions, herpes zoster with postherpetic neuralgia, and spinal cord disorders. It is idiopathic in 25% of cases. Pathogenesis is obscure. Reflex sympathetic dystrophy may be a disorder of pain signaling and regulation as well as a persisting neural injury generating pain signals with reflex neurologic mechanisms involved. It has been proposed that primary afferent nociceptor neurons develop a1-adrenoreceptors, making them responsive to norepinephrine released by sympathetic nerve terminals. This may in part explain the reduction in pain by a1-antagonists. Central mechanisms of neuronal hyperresponsivity may also be a factor, especially at later stages of this syndrome.

Pathology: Skin and subcutaneous tissue are usually normal. Affected bone is hyperemic with patchy osteoporosis. There may be synovial proliferation and inflammation.

Demographics: In adults, there is a slight female predominance. It is reported to occur at all ages, most commonly between 40 and 60 years. In children, 80% of patients are female, often with lower extremity involvement.

Cardinal Findings: Three overlapping stages have been recognized in reflex sympathetic dystrophy, although the validity and usefulness of this approach has been questioned. The acute stage lasts 3 to 6 months and is characterized by intense limb pain, tenderness, swelling, and vasomotor disturbances (cyanosis or erythema, hyperhidrosis). The dystrophic (or subacute) stage lasts 6 to 12 months, during which acute symptoms resolve (often incompletely) while atrophic changes in the skin evolve and chronic aching or burning pain persists. Skin becomes dry and may be edematous or develop a brawny thickening. In the atrophic stage, skin and subcutaneous atrophy and contractures predominate.

—Site: Reflex sympathetic dystrophy is usually unilateral and affects the upper extremity more so than the lower extremity. It may involve the entire hand or foot. It may be bilateral in 25% of cases.

—Pain: Pain is often constant, burning, and severe early on. Chronic aching pain or myofascial limb pain may be present.

—Appearance: There are swelling, trophic skin changes, signs of vasomotor (Raynaud’s phenomenon, temperature variation), and sudomotor (sweating) instability. Pitting or nonpitting edema is usually present.

—Tenderness: Exquisite tenderness occurs, especially in periarticular tissues. Allodynia (pain induced by light touch) and hyperpathia (persistent pain after light pressure) are characteristic.

—Neurologic changes: Tremor, incoordination, weakness, or sensory changes may occur.

Uncommon Findings: Nail changes and segmental involvement (one to two digital rays of the hand or foot) or involvement of knee, hip, portions of bone, or the femoral head can be seen.

Diagnostic Tests: Common lab tests (CBC, chemistry, ESR) are not useful.

Imaging: Plain radiography shows patchy or mottled osteopenia; however, this is neither sensitive nor specific. Late cases have a ground-glass appearance. Cortical breaks and crumbling erosion may also be noted. Scintigraphy is the most useful objective test. Three-phase bone scan shows asymmetry in all three phases, increased or decreased blood flow, pool, and uptake phases.

Keys to Diagnosis: Look for pain and swelling in a distal extremity with trophic skin changes and vasomotor instability, often with a history of trauma (especially fracture), myocardial infarction, hemiplegic stroke, or peripheral nerve injury.

Therapy: Early diagnosis or prevention is important, especially in high-risk individuals (trauma, myocardial infarction, hemiplegia). Treat the underlying problem, if one is identified. Once a diagnosis of reflex sympathetic dystrophy is established, initiate therapy early: analgesia, local heat, ice, physical therapy, and stress-loading and desensitization programs. Pharmacologic maneuvers include sympathetic blockade, followed by sympathectomy in those who respond (70%–80% improve). Oral a1-antagonists (phenoxybenzamine, prazosin, terazosin, doxazosin) may be useful. Systemic corticosteroids (e.g., prednisone 20–60 mg/day for 4–6 weeks) may be useful in patients with “hot” bone scans, especially early in the disease. Treatment with calcitonin and topical ketamine has been studied. Recalcitrant disease may require chronic pain management. Rarely, amputation has been resorted to; even this measure may leave the patient with phantom limb pain.

Prognosis: Overall, 50% of patients still have significant pain or disability after 2 years.

BIBLIOGRAPHY

Schwartzman RJ, Popescu A. Reflex sympathetic dystrophy. Curr Rheumatol Rep 2002; 4:165–169. PMID:11890882