You are in: eMedicine Specialties > Radiology > MUSCULOSKELETAL Reflex Sympathetic DystrophyArticle Last Updated: Aug 26, 2005AUTHOR AND EDITOR INFORMATIONSection 1 of 10
  Author: Lawrence E Holder, MD, Clinical Professor, Department of Radiology, University of Florida, Shands Jacksonville Medical Center Lawrence E Holder is a member of the following medical societies: American College of Nuclear Physicians, American College of Radiology, American Medical Association, Association of University Radiologists, MedChi, Radiological Society of North America, and Society of Nuclear Medicine Editors: Leon Lenchik, MD, Director, Densitometry Minifellowship, Assistant Professor, Department of Radiology, Wake Forest University Medical Center; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Wilfred CG Peh, MD, MBBS, FRCP(Glasg), FRCP(Edin), FRCR, MHSM, Clinical Professor, Faculty of Medicine, National University of Singapore; Senior Consultant Radiologist, Programme Office, Singapore Health Services; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; Felix S Chew, MD, MBA, EdM, Professor, Department of Radiology, Vice Chairman for Radiology Informatics, Section Head of Musculoskeletal Radiology, University of Washington Author and Editor Disclosure Synonyms and related keywords: complex regional pain syndrome type I, CRPS-I, sympathetically mediated pain syndrome, SMPS, causalgia, algodystrophy, algodynia, Sudek's atrophy, Sudek atrophy, shoulder-hand syndrome, RSD INTRODUCTIONSection 2 of 10
  BackgroundReflex sympathetic dystrophy (RSD) is an incompletely understood response of the body to an external stimulus, resulting in pain that usually is nonanatomic and disproportionate to the inciting event or expected healing response. As early as the 1930s and 1940s, a short circuit in the reflex arc between somatic afferent sensory fibers and autonomic sympathetic efferents was postulated to explain overall increased sympathetic stimulation. Currently, no specific pathologic, histologic, or biochemical markers of this condition exist. Although controversy continues regarding the term, definition, and process of diagnosis, the presence of sympathetically maintained pain is accepted as an etiology for, or at least as a significant component of, many regional pain problems. PathophysiologySymptomatically, RSD is a condition of the extremities. RSD is known and accepted best when it affects the upper extremity, predominantly in a regional distribution involving the distal forearm, wrist, and hand, and occasionally the arm and shoulder. No pathophysiologic mechanism has been established. Efferent sympathetic nervous system overactivity and/or abnormal activity involving spinal internuncial neurons, peripheral nociceptors, and/or mechanoreceptors have been postulated. Many biomechanical factors have been considered, beginning with tissue injury as an initial inciting event, with substance P, histamine, and prostaglandins all possibly involved. Other possible etiologies include vasodilatation, shunting, and regional hypoxia associated with nociceptor stimulation, as well as the role of alpha-adrenergic receptors in maintaining and controlling thermoregulatory modulation. Segmental involvement of 1,2, or 3 rays in the hand has been reported infrequently, according to Kline and Holder, and bilateral involvement is rare to nonexistent. In the lower extremity (most often foot and ankle), a less well-defined clinical pattern also is associated with a similar spectrum of pathophysiologic speculations. In the knee, potentially sympathetically related postoperative and posttraumatic signs and symptoms have been ascribed to RSD or other neuroregulatory processes but with less accepted clinical or diagnostic standards of reference. More recently, the term complex regional pain syndrome (CRPS) has been introduced to encompass a variety of chronic pain syndromes, with RSD labeled as type I. All sympathetically maintained pain syndromes (SMPS) may not be RSD. FrequencyUnited StatesThe incidence of RSD following trauma is difficult to estimate, since the literature is replete with studies in which clinical criteria for the diagnosis of RSD vary dramatically, with many often equating unexplained pain to RSD. For example, upper extremity RSD, as understood and treated by hand surgeons, is described differently than lower extremity RSD diagnosed by rheumatologists or hip RSD described by obstetricians. Some authors suggest that 8-10% of patients with fracture develop RSD, but in the author's experience, the frequency is much lower. Mortality/MorbidityMost RSD patients recover completely over time. Uncommonly, the syndrome progresses to the point of incapacitation and a "claw hand" is observed. SexIn the upper extremity, the author's experience demonstrates a clear female preponderance, especially in patients presenting to the orthopedic surgeon. AgePatients younger than 50 years predominate. In the upper extremity, orthopedic surgeons see children only rarely. Rheumatologists, who generally use less strict criteria for diagnosis, report a slightly higher frequency of involvement in children. Similarly, pediatricians report a moderate frequency of lower extremity neurovascular or neuroregulatory disease in children that has been termed RSD. In these children, a bone scan pattern often reveals marked decreased tracer uptake on delayed images compared to increased uptake in adults; therefore, this may represent a different condition, such as pseudodystrophy. AnatomyRSD involving the hand, wrist, shoulder, ankle, and foot has been established, with diffuse involvement of adjacent carpals or tarsals, metacarpals or metatarsals, phalanges, and, frequently, the distal forearm or leg. Rarely, segmental involvement of 1, 2, or 3 rays of the hand is observed. Involvement of the knee, although described, is less well documented and along with focal pain conditions in the hip (often interchangeably termed RSD or transient osteoporosis) may be a different process. Clinical DetailsRadiologists and orthopedic surgeons usually agree to define RSD (as stated by Schutzer) as an "excessive or exaggerated response to an injury of an extremity, manifested by four somewhat constant characteristics: (1) intense or unduly prolonged pain, (2) vasomotor disturbances, (3) delayed functional recovery, and (4) various associated trophic changes." The key feature is pain, which often is the initial presenting symptom. Various clinical schemas have been proposed that relate stages of disease to signs and symptoms and the time elapsed since the inciting event. One example of staging by Rosenthal and Wortmann is as follows:
Preferred ExaminationRadiologic examination Radionuclide bone imaging (RNBI) is the only generally accepted imaging technique to provide objective and relatively specific evidence of RSD in the upper and lower extremities, predominantly the hands and feet. Delayed bone imaging has been reported to be up to 100% sensitive for the variant of sympathetically maintained pain termed RSD by hand and foot surgeons. Plain radiography is only 60% sensitive and not specific; when positive, radiographs often show only osteoporosis, occasionally in combination with soft tissue swelling or diffuse soft tissue atrophy. No consistent findings have been found in the occasional study done with other imaging modalities, and none are suggested for diagnosis. Nonimaging diagnostic testing Pain in response to mild cooling stimuli: A drop of acetone or ethyl chloride spray provoking severe pain suggests SMPS rather than a sympathetically independent pain syndrome (SIPS). Phentolamine test: The blocking of alpha-adrenergic receptors by intravenous phentolamine compared to a placebo helps classify patients as SMPS versus SIPS. Limitations of TechniquesPatients are observed who present with acute or subacute pain and vasomotor or neuroregulatory signs or symptoms and who do not demonstrate the classic diffuse increased uptake on delayed RNBI. The relationship of these patients to those with abnormal RNBI remains unexplained. DIFFERENTIALSSection 3 of 10
[Reiter Syndrome, Musculoskeletal] Abdominal Aortic Aneurysm, Diagnosis Osteoarthritis, Primary Osteomyelitis, Acute Pyogenic Osteomyelitis, Chronic Rheumatoid Arthritis, Hands
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| Media file 1: Reflex sympathetic dystrophy of the hand. Delayed image palmar view reveals increased tracer diffusely involving the entire right wrist, metacarpals, and phalanges, with juxta-articular accentuation. Relatively less increased uptake is observed distally, but all areas are involved. The dot of increased activity distal to the third ray is a hot marker indicating the right side. | |
 | View Full Size Image | Media type: Photo |
| Media file 2: Reflex sympathetic dystrophy of the foot. Delayed image plantar view reveals increased tracer uptake diffusely involving the lowermost right leg, ankle, tarsals, metatarsals, and phalanges. Uptake is less distally than proximally, but all areas are involved. The dot of increased activity distal to fifth toe is a hot marker indicating the right side. | |
 | View Full Size Image | Media type: Photo |
Reflex Sympathetic Dystrophy excerpt
Article Last Updated: Aug 26, 2005
