low sensitivity of fwave in the electrodiagnosis of carpal tunnel syndrome objective previous studies showed fwave inversion finv as a sensitive method in the electrodiagnosis of early stage of carpal tunnel syndrome cts this study aimed at evaluating the sensitivity and specificity of fwave and nerve conduction velocity ncv testing in ctsmethods we consecutively enrolled 244 cases and 108 controls fwaves analysis included fwave minimum and mean latencies fwave persistence and chronodispersion meanfcmap amplitude ratio finv specificity and sensitivity of fwaves parameters were calculated in the whole sample of cts patients and by grouping the patients according to cts severity multivariate logistic regression was also performed using finv as a dependent variableresults in the whole sample the sensitivity of fmeaninv and of medianulnar ncv comparative testing was 508 and 937 respectively finv sensitivity dropped to 8 in cts early stage finv could be predicted only by distal motor latency of the median nerve the sensitivity of all fwave parameters increased only in the most severe stages of ctsconclusions this study does not confirm the electrodiagnostic usefulness of finv in early stage of cts all fwave parameters including finv are much less sensitive than conventional ncv in cts electrodiagnosis fwave does not add further useful information specifically related to cts