Abstract and Introduction
Complex regional pain syndrome (CRPS) is a severely painful condition that presents with a constellation of symptoms. The understanding of the pathophysiology of CRPS has evolved over time, as have the diagnostic criteria. Our primary objective was to identify screening and diagnostic tools for CRPS and summarize their feasibility, measurement properties, and study quality. A secondary objective was to identify screening and diagnostic tools used for CRPS in pediatric populations (0–21 years of age). A systematic review of English articles in electronic databases (PsycINFO, MEDLINE, Embase, CINAHL, CENTRAL, and Web of Science) was conducted with the aid of a librarian in November 2018 and updated in July 2020. Studies were included if the tool was a screening or diagnostic tool, the tool included self-report or physical examination, and the primary objective of the study was to evaluate the measurement properties or feasibility of use. For each study, data were extracted for quality indicators using the QUADAS-2 tool. No screening tools were identified. Four diagnostic tools were identified: the Veldman criteria, International Association for the Study of Pain criteria, Budapest Criteria, and Budapest Research Criteria. There are no diagnostic tools validated for use in pediatric CRPS. Because there are no extant screening tools for CRPS, all people with suspected disease should undergo rapid diagnostic assessment by a clinician. For adults, the Budapest Criteria are the preferred diagnostic tool. Future research is recommended to develop a diagnostic tool for pediatric populations and screening tools for both pediatric and adults.
Complex regional pain syndrome (CRPS) is a severely painful condition typically in the distal region of a limb. It most commonly occurs after a trauma, for which the pain is disproportionate to the extent of trauma and tissue damage. Further to pain, an array of symptoms are usually present including abnormalities in sensation, trophic changes, vasomotor, motor, and autonomic dysfunction. There are 2 types of CRPS: CRPS-1, which refers to CRPS in the absence of nerve damage, and CRPS-2 with related nerve damage. The pathophysiology is not fully understood, although a constellation of factors have been proposed including neurogenic inflammation, maladaptive plasticity, and sensitization of nociceptors.
Terminology and diagnostic criteria for CRPS have evolved. During the American Civil War, causalgia was used to describe burning pain after nerve injury in wounded soldiers, associated with allodynia, color, and trophic changes.[23,24] It was later described as reflex sympathetic dystrophy in 1943. Other terms included shoulder-hand syndrome, algodystrophy, and Sudeck atrophy, to describe similar physiological phenomena. In 1993, the International Association for the Study of Pain (IASP) revised their taxonomy and introduced the term CRPS.
The incidence of CRPS has been reportedly 5.5–25.2 cases per 100,000 person years in the United States and the Netherlands, respectively. Females are 3 times more likely to be diagnosed with CRPS, with cases most common in women of age 61 to 70 years. The upper extremity is more frequently affected than the lower extremity, and nearly half report a fracture as the inciting trauma. In children and adolescents, CRPS is rare, although the exact incidence remains unknown. Pediatric CRPS affects predominately females (85%) and most often in the lower extremity (71%).
A systematic review in 2014 revealed mixed results to explain the prognosis of CRPS. The authors concluded that some symptoms (pain, swelling, discoloration, and temperature changes) resolve between 6 and 13 months after symptom onset, whereas other symptoms (function and motor changes) tend to be chronic in nature (>1 year). Authors speculate that perhaps early interventions may be correlated with earlier symptom resolution. Some studies suggest CRPS is milder in children with a more favorable prognosis; however, this is not well understood.[8,18,22]
Complex regional pain syndrome is highly complex and given the large number of potential signs and symptoms, it can be challenging to diagnose. There is no gold standard radiological, laboratory, genetic, or electrical diagnostic test for CRPS. Over time, several clinical tools specifying signs and symptoms have been developed; however, they vary in their description of the disease. Having clear diagnostic criteria would allow clinicians to identify the disease accurately and initiate appropriate treatments. A screening tool would further allow clinicians to expedite access to treatments and referrals to specialists. From a research lens, a consensus on diagnostic criteria would aid in defining study populations, allowing comparisons between studies.
The primary objective was to identify and summarize the measurement properties and feasibility of screening and diagnostic tools for CRPS in all ages. A secondary objective was to identify and summarize screening and diagnostic tools used for CRPS in children and adolescents up to 21 years of age.