biostudies-literatureUnknown12(11)Falsetti P<h4>Background</h4>There is little consensus on ultrasound (US) normative values of cross-sectional area of median nerve (MN-CSA) in carpal tunnel syndrome (CTS) because of its dependency on anthropometric parameters. We aim to propose a novel anthropometric-independent US parameter: MN-CSA/flexor radialis carpi CSA (FCR-CSA) ratio ("Nerve Tendon Ratio", NTR), in the diagnosis of clinically and electrodiagnostic (EDS)-defined CTS.<h4>Methods</h4>74 wrists of 49 patients with clinically defined CTS underwent EDS (scored by the 1-5 Padua Scale of electrophysiological severity, PS) and US of carpal tunnel with measurement of MN-CSA (at the carpal tunnel inlet), FCR-CSA (over scaphoid tubercle) and its ratio (NTR, expressed as a percentage). US normality values and intra-operator agreement were assessed in 33 healthy volunteers.<h4>Results</h4>In controls, the mean MN-CSA was 5.81 mm², NTR 64.2%. In 74 clinical CTS, the mean MN-CSA was 12.1 mm², NTR 117%. In severe CTS (PS &gt; 3), the mean MN-CSA was 15.9 mm², NTR 148%. In CTS, both MN-CSA and NTR correlated with sensitive conduction velocity (SCV) (<i>p</i> &lt; 0.001), distal motor latency (DML) (<i>p</i> &lt; 0.001) and PS (<i>p</i> &lt; 0.001), with a slight superiority of NTR vs. MN-CSA when controlled for height, wrist circumference and weight. In CTS filtered for anthropometric extremes, only NTR maintained a correlation with SCV (<i>p</i> = 0.023), DML (<i>p</i> = 0.016) and PS (<i>p</i> = 0.009). Diagnostic cut-offs were obtained with a binomial regression analysis. In those patients with a clinical diagnosis of CTS, the cut-off of MN-CSA (AUROC: 0.983) was 8 mm² (9 mm² with highest positive predictive value, PPV), while for NTR (AUROC: 0.987), the cut-off was 83% (100% with highest PPV). In patients with EDS findings of severe CTS (PS &gt; 3), the MN-CSA (AUROC: 0.876) cut-off was 12.3 mm² (15.3 mm² with highest PPV), while for NTR (AUROC: 0.858) it was 116.2% (146.0% with highest PPV).<h4>Conclusions</h4>NTR can be simply and quickly calculated, and it can be used in anthropometric extremes.Diagnostics (Basel, Switzerland)2621https://www.ebi.ac.uk/biostudies/studies/S-EPMC9689936biostudies-literatureA Novel Ultrasonographic Anthropometric-Independent Measurement of Median Nerve Swelling in Carpal Tunnel Syndrome: The "Nerve/Tendon Ratio" (NTR).PMC9689936Conticini EGentileschi SCantarini LAcciai CFrediani BGinanneschi FBardelli MD'Alessandro RFalsetti PD'Alessandro MBaldi CD'Ignazio EAl Khayyat SGfalseA Novel Ultrasonographic Anthropometric-Independent Measurement of Median Nerve Swelling in Carpal Tunnel Syndrome: The "Nerve/Tendon Ratio" (NTR).<h4>Background</h4>There is little consensus on ultrasound (US) normative values of cross-sectional area of median nerve (MN-CSA) in carpal tunnel syndrome (CTS) because of its dependency on anthropometric parameters. We aim to propose a novel anthropometric-independent US parameter: MN-CSA/flexor radialis carpi CSA (FCR-CSA) ratio ("Nerve Tendon Ratio", NTR), in the diagnosis of clinically and electrodiagnostic (EDS)-defined CTS.<h4>Methods</h4>74 wrists of 49 patients with clinically defined CTS underwent EDS (scored by the 1-5 Padua Scale of electrophysiological severity, PS) and US of carpal tunnel with measurement of MN-CSA (at the carpal tunnel inlet), FCR-CSA (over scaphoid tubercle) and its ratio (NTR, expressed as a percentage). US normality values and intra-operator agreement were assessed in 33 healthy volunteers.<h4>Results</h4>In controls, the mean MN-CSA was 5.81 mm², NTR 64.2%. In 74 clinical CTS, the mean MN-CSA was 12.1 mm², NTR 117%. In severe CTS (PS &gt; 3), the mean MN-CSA was 15.9 mm², NTR 148%. In CTS, both MN-CSA and NTR correlated with sensitive conduction velocity (SCV) (<i>p</i> &lt; 0.001), distal motor latency (DML) (<i>p</i> &lt; 0.001) and PS (<i>p</i> &lt; 0.001), with a slight superiority of NTR vs. MN-CSA when controlled for height, wrist circumference and weight. In CTS filtered for anthropometric extremes, only NTR maintained a correlation with SCV (<i>p</i> = 0.023), DML (<i>p</i> = 0.016) and PS (<i>p</i> = 0.009). Diagnostic cut-offs were obtained with a binomial regression analysis. In those patients with a clinical diagnosis of CTS, the cut-off of MN-CSA (AUROC: 0.983) was 8 mm² (9 mm² with highest positive predictive value, PPV), while for NTR (AUROC: 0.987), the cut-off was 83% (100% with highest PPV). In patients with EDS findings of severe CTS (PS &gt; 3), the MN-CSA (AUROC: 0.876) cut-off was 12.3 mm² (15.3 mm² with highest PPV), while for NTR (AUROC: 0.858) it was 116.2% (146.0% with highest PPV).<h4>Conclusions</h4>NTR can be simply and quickly calculated, and it can be used in anthropometric extremes.2022-01-01T00:00:00Z2022 Oct2025-04-19T16:10:24.735Z2025-02-19T01:56:43.27ZS-EPMC96899363635946510.3390/diagnostics12112621