validity of current electrodiagnostictechniques in the diagnosis of carpal tunnel syndrome

background : determining the validity of current median sensory nerve conduction techniques for diagnosis of carpal tunnel syndrome (cts). methods: 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. results: 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. conclusions : 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.