Quantitative evaluation of very acute stage of complex regional pain syndrome after stroke using three-phase bone scintigraphy

Abstract

Three-phase bone scintigraphy (TPBS) is an objective diagnostic test for complex regional pain syndrome (CRPS). The diagnostic importance of an increased uptake on the delayed phase has been proven in early CRPS, but that of the vascular and blood pool phases has not. The purpose of this study is to improve the diagnostic strength of the very acute stage of CRPS after stroke through a combined quantitative evaluation of each TPBS phase. Quantitative TPBS analysis was performed in 26 post-stroke hemiplegic patients with very acute stage of CRPS and in 12 controls with no CRPS after brain lesion. Regions of interest (hands without fingers--carpal bones, metacarpal bones and metacarpopharyngeal joints) were selected and the count ratios of the affected to unaffected sides were calculated. The maximum values of control in each phase were used as the criteria of positive findings of each TPBS phase. Eleven patients in the vascular phase, 13 in the blood pool phase and 17 in the delayed phase had a higher assumption than the maximum values and a sensitivity of 42.3%, 50% and 65.4%, respectively. Twenty-one of 26 patients were interpreted as abnormal when at least one phase showed a positive finding. As a result, increased sensitivity of 80.8% and identical specificity of 100% were achieved. These findings suggest that the combination of quantitative evaluation of each TPBS phase can improve the diagnostic strength of the very acute stage of CRPS after stroke.