en Physical Medecine& Rehabilitaion Physical Medecine& Rehabilitaion Original Research Original Research <p> <strong> Background </strong>: Determining the validity of current median sensory nerve conduction techniques for diagnosis of carpal tunnel syndrome (CTS). </p><p> <strong> Methods: </strong>Eighty five patients with clinical diagnosis of CTS were compared with the same number of healthy people. The validity of electrodiagnostic tests were compared in a case-control manner. These electrodiagnostictechniques included long-segment, short-segment, 2-segment and relative slowing studies as well as disto-proximal ratio. Receiver Operating Characteristic (ROC) curve employed for comparison, determining the optimal cut-off points for each test. Validity was evaluated with likelihood ratio. </p><p> <strong> Results: </strong>Likelihood ratio (LHR) for Radial-median sensory latency difference was ∞, while LHR for ulnar-median sensory latency difference was 16.9. Sensitivity of Two-segment method was 98.8% and mixed palm-wrist median Nerve Conduction Velocity (NCV) study showed a sensitivity and specificity of 97.6%, 83.5% respectively<strong>.</strong> </p><p> <strong> Conclusions </strong>: Radial-median latency difference study (optimal cut-off point ≥0.5) and study of wrist-segment NCV (optimal cut-off point <50.45) were the most valuable techniques in diagnosis of CTS, respectively. Median-ulnar latency difference study and disto-proximal ratio study had more diagnostic implication than long and short (mixed) segment technique in this regard. </p><p>  <strong></strong></p> Carpal Tunnel Syndrome,Electrodiagnosis, ROC curve. 276 282 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1-675&slc_lang=en&sid=1 Bina Eftekharsadat binasadat@yahoo.com 200319475328460012837 200319475328460012837 No Physical Medicine and Rehabilitation Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. Tannaz Ahadi tannaz.ahadi@yahoo.com 200319475328460012838 200319475328460012838 Yes Physical Medicine and Rehabilitation Department, Iran University of Medical Sciences, Tehran, Iran. Gholam Reza Raissi grezaraissi@yahoo.com 200319475328460012839 200319475328460012839 No Physical Medicine and Rehabilitation Department, Iran University of Medical Sciences, Tehran, Iran. Saied Kazem Shakoory sk0531ir@yahoo.com 200319475328460012840 200319475328460012840 No Physical Medicine and Rehabilitation Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. Seyed Mohammad Fereshtehnejad smf681@yahoo.com 200319475328460012841 200319475328460012841 No Firoozgar Clinical Research Development Center (FCRDC), Iran University of Medical Sciences, Tehran, Iran.