• Johann Lambeck, Eva M Kesenheimer, Barbara Kleinmann, and Matthias Reinhard.
• Department of Neurology and Neurophysiology, University Medical Center Freiburg, Freiburg, Germany.
• Pain Pract. 2021 Mar 1; 21 (3): 308-315.

BackgroundThe tourniquet ischemia test (IT) is a hitherto rarely used tool for the diagnostic work-up of patients with suspected complex regional pain syndrome (CRPS). This analysis aims to determine the sensitivity and specificity of this test, and elucidate factors that can influence the test result.MethodsConsecutive data on clinical presentation, results of the IT and other diagnostic tests, and clinical characteristics were analyzed from patients presenting at our autonomic laboratory between 2000 and 2011. IT results were compared with the final clinical diagnosis at discharge, and statistical analysis was performed to determine specificity, sensitivity, and positive and negative predictive values of the IT.ResultsA total of 78 patients were assessed. IT results were positive (≥50% reduction in pain during ischemia) in 26 cases and negative in 52 cases. CRPS was the final diagnosis in 45 cases, and in 33 cases, a different diagnosis was made. This results in a test sensitivity of 49% and a specificity of 88%, with a positive predictive value of 85% and a negative predictive value of 56%. Age, sex, the type and stage of CRPS, and the affected extremity did not influence the test result in a statistically significant manner. Specificity worsened to 76% if any pain reduction was rated as a positive test result.ConclusionsA positive tourniquet IT has a high positive predictive value for the diagnosis of CRPS. It is thus useful as a confirmatory assay in patients with suspected CRPS. Low sensitivity rules out its use as a screening test.SignificanceThis study retrospectively analyzed the clinical significance of the tourniquet IT that was routinely used in patients with suspected CRPS. It showed that a positive IT result is useful as a confirmatory assay in patients fulfilling the clinical criteria.© 2020 The Authors. Pain Practice published by Wiley Periodicals LLC on behalf of World Institute of Pain.

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