A new diagnostic morphological parameter for the Carpal tunnel syndrome: The palmaris longus tendon cross-sectional area

Carpal tunnel syndrome (CTS) is correlated with increased intracarpal canal pressure (ICP). The effect of palmaris longus tendon (PLT) loading on ICP is documented in previous researches. PLT loading induces the greatest absolute increase in ICP. Therefore, to analyze the connection between the PLT and CTS, we newly made the measurement of the PLT cross-sectional area (PLTCSA). We assumed that PLTCSA is a reliable diagnostic parameter in the CTS. PLTCSA measurement data were acquired from 21 patients with CTS, and from 21 normal subjects who underwent wrist magnetic resonance imaging (W-MRI). We measured the PLTCSA at the level of pisiform on W-MRI. The PLTCSA was measured on the outlining of PLT. The two different cutoff values in the analysis were determined using receiver operating characteristic (ROC) analysis. The mean PLTCSA was 2.34 ± 0.82 mm(2) in the normal group and 3.97 ± 1.18 mm(2) in the CTS group. ROC curve analysis concluded that the best cutoff point for the PLTCSA was 2.81 mm(2), with 76.2% sensitivity, 71.4% specificity, and area under the curve of 0.88 (95% CI, 0.78‐0.98). PLTCSA is a sensitive, new, objective morphological parameter for evaluating CTS.