Objectives: Joint and bone alterations are seldom mentioned in the diagnostic criteria for complex regional pain syndrome (CRPS) even though they are important for long-term outcome. Altered periarticular bone metabolism can be detected by 3-phase bone scintigraphy (TPBS). Although frequently examining the diagnostic efficacy of TPBS is debatable.
Methods: In all, 78 TPBS (45 CRPS/33 control group) were evaluated qualitatively and quantitatively. Sensitivity and specificity of the qualitative blinded reviewer analysis (n=57) compared with quantitative region of interest (ROI)-based analysis over the metacarpophalangeal, proximal, and distal interphalangeal joints (n=74) were evaluated. Patients' sex, age, duration of CRPS, inciting event, extent of joint alteration, and handedness were included as covariables.
Results: Qualitative blinded reviewer TPBS analysis had a high specificity (83%-100%). However, sensitivity was 31% to 50%. Interrater reliability was moderate (kappa score 0.56). Using the ROI-based evaluation, the highest sensitivity (69%) and specificity (75%) (ROI score > or =1.32) was shown for phase 3, whereas sensitivity of phases 1 and 2 rapidly declined to 50%. Duration of CRPS until TPBS was the only variable with significant impact on ROI scores of phase 3 (F=23.7; P=0.000; R=0.42). ROI scores declined with increasing duration of CRPS.
Discussion: In conclusion, TPBS is a highly specific tool for diagnosing CRPS of the upper limb. ROI evaluation of phase 3 within the first 5 months after onset of CRPS is an appropriate additional diagnostic tool to confirm or exclude CRPS of the upper extremity.