Objective evaluation of the ``scratch collapse test'' for the diagnosis of carpal tunnel syndrome

Abstract

PurposeEvaluate the Scratch Collapse Test in an objective way, by replacing the subjective evaluation made by the physician with an objective evaluation measure, made with a digital dynamometer. MethodsObservational study carried out, in 90 patients divided into three groups of 30 patients, taking into account the electromyographic study of the median nerve in the carpal tunnel (no alteration, moderate, severe).The external rotation of the shoulder was measured in four different situations (no scratch, scratch over the carpal tunnel, scratch in the dorsum of the wrist and scratch in the shoulder). ResultsThere were no statistical differences in the result of the strength in any of the four different situations in patients without carpal tunnel of with moderate carpal tunnel syndrome. However, there were statistical differences between the basal measurement (without scratching) and the measurement after tunnel scratching in patients with severe carpal tunnel syndrome. But this statistical difference was only 0.08 kg in the average measure, and this difference is clinically undetectable and far for producing a real collapse of the external rotation of the shoulder. ConclusionThe Scratch Collapse Test is not a valid diagnostic exam for carpal tunnel syndrome if the strength is measured in an objective manner.