Background: The scratch collapse test (SCT) is a clinical examination maneuver 
that has been previously reported as a reliable and reproducible test to 
diagnose carpal tunnel syndrome (CTS). The initial study by Cheng et al in 2008 
showed a simple test with high sensitivity. However, subsequent attempts to 
reproduce those findings have resulted in lower accuracy. Our goal was to 
evaluate the use of the SCT for patients presenting with symptoms of pain, 
numbness, or weakness in an upper extremity. Methods: Forty patients were 
referred to the electrodiagnostic (EDX) lab for evaluation of an upper 
extremity. One blinded examiner who was familiar with the maneuver performed the 
SCT on all 40 patients. Another physician or technician performed the nerve 
conduction study and electromyography. Patient history and accompanying physical 
examination findings were not revealed to the SCT examiner. Results: The 
relationship between the SCT performed by a blinded examiner and the EDX 
performed by blinded examiners was nonsignificant (P = .676) and showed a 
sensitivity of 0.48, specificity of 0.59, positive predictive value of 0.61, and 
negative predictive value of 0.45. Conclusion: Based on this study and previous 
findings by other authors, we would advise against the use of the SCT in CTS for 
important patient-care decisions, such as surgical decision-making, until future 
research is done. It is possible that the SCT, in combination with other 
physical examination maneuvers, could increase diagnostic accuracy and enhance 
patient management.