Complex Regional Pain Syndrome I (CRPS I): Prospective study and laboratory evaluation

Objective: To relate clinical features to autonomic laboratory indices used in the diagnosis of Complex Regional Pain Syndrome type I (CRPS I) (reflex sympathetic dystrophy) to generate improved diagnostic criteria. Description: CRPS I is a chronic pain syndrome, characterized by diffuse li mb pain with allodynia and prominent vasomotor and sudomotor dysfunction. Methods: We conducted a prospective study on 102 patients referred for poss ible CRPS I. These patients completed a structured questionnaire and underw ent neurologic examination, with special attention to the evaluation of cli nical features of vasomotor, sudomotor, motor, and sensory, including pain, dysfunction. All patients were tested using a standard autonomic protocol that compared side-to-side skin temperature, resting sweat output, and quan titative sudomotor axon reflex test (QSART) measurements. Composite autonom ic clinical (CRPS-Sx) and laboratory (CRPS-LAB) scores were defined. The cl inical (subjective and objective) and the laboratory data were analyzed usi ng Pearson's correlation analysis and Bonferroni's probability value to ass ess concordance and their value in correctly diagnosing CRPS I. Results: All cases occurred after limb injury. One-third of cases did not f ulfill our criteria of CRPS I. Highly significant correlations (p < .001) w ere found among certain clusters of symptoms and signs that shared unifying pathophysiologies. CRPS-Sx correlated with CRPS-LAB (p = .035). The indice s that correlated most reliably with clinical data and with each other were RSO, QSART, and skin temperature reductions. Conclusion: Clinical and autonomic laboratory probability scores correlate in an internally consistent manner. Both CRPS-Sx and CRPS-LAB are sensitive and reliable tools to formulate a correct diagnosis of CRPS I and can be c ombined to provide an improved set of diagnostic criteria for CRPS I.