SENSITIVITY AND SPECIFICITY OF VIBROMETRY FOR DETECTION OF CARPAL-TUNNEL SYNDROME

A cross-sectional study was performed to assess the utility of vibrota ctile thresholds (VTs) obtained before and after a 10-minute period of wrist flexion as a method for detection of carpal tunnel syndrome (CT S) among adult subjects. Subjects with hand discomfort were recruited from patients referred to a university-based electromyography laborato ry. Asymtomatic subjects were recruited from among office and technica l staff at a professional school. In addition, to electrophysiologic e valuation (EP), all subjects were offered VT measurement of the index and small fingers, bilaterally, before and after a 10-minute; period o f wrist flexion. A total of 144 subjects were recruited and three hand -condition groups were established: 57 hands had symptoms and EP resul ts compatible with CTS (Group 1), 58 hands had symptoms compatible wit h CTS and normal EP results (Group 2), and 123 hands had no symptoms a nd normal EP results (Group 3). Group 1 was considered the ''disease-p ositive'' group, and Groups 2 and 3 were both considered ''disease-neg ative'' groups. Analyses were performed separately for dominant and no ndominant hands, and results were pooled when appropriate. Outcomes of interest were the VTs obtained from the index and small fingers befor e and after 10 minutes of maximal voluntary wrist flexion as well as v ariables calculated from them. Significant differences in mean VT were observed between the three hand-condition groups for most of the outc omes evaluated. At any given level of specificity, the sensitivity of vibrometry performed after 10 minutes of wrist flexion was approximate ly two times that obtained before wrist flexion for detection of elect rophysiologically confirmed CTS. At specificities of 70 and 80%, the b est sensitivity observed among vibrometry outcomes obtained after wris t flexion were 61 and 57%, whereas the best sensitivities observed amo ng vibrometry outcomes obtained before wrist flexion were 35 and 28%.