Complex regional pain syndrome: are the IASP diagnostic criteria valid andsufficiently comprehensive?

This is a multisite study examining the internal validity and comprehensive ness of the International Association for the Study of Pain (IASP) diagnost ic criteria for Complex Regional Pain Syndrome (CRPS). A standardized sign/ symptom checklist was used in patient evaluations to obtain data on CRPS-re lated signs and symptoms in a series of 123 patients meeting IASP criteria for CRPS, Principal components factor analysis (PCA) was used to detect sta tistical groupings of signs/symptoms (factors). CRPS signs and symptoms gro uped together statistically in a manner somewhat different than in current IASP/CRPS criteria. As in current criteria, a separate pain/sensation crite rion was supported. However, unlike in current criteria, PCA indicated that vasomotor symptoms form a factor distinct from a sudomotor/edema factor. C hanges in range of motion, motor dysfunction, and trophic changes, which ar e not included in the IASP criteria, formed a distinct fourth factor. Score s on the pain/sensation factor correlated positively with pain duration (P < 0.001), but there was a negative correlation between the sudomotor/edema factor scores and pain duration (P < 0.05). The motor/trophic factor predic ted positive responses to sympathetic block (P < 0.05). These results sugge st that the internal validity of the IASP/CRPS criteria could be improved b y separating vasomotor signs/symptoms (e.g. temperature and skin color asym metry) from those reflecting sudomotor dysfunction (e.g. sweating changes) and edema. Results also indicate motor and trophic changes may be an import ant and distinct component of CRPS which is not currently incorporated in t he IASP criteria. An experimental revision of CRPS diagnostic criteria for research purposes is proposed. Implications for diagnostic sensitivity and specificity are discussed. (C) 1999 International Association for the Study of Pain. Published by Elsevier Science B.V.