Assessing Diagnostic and Severity Grading Accuracy of Ultrasound Measurements for Carpal Tunnel Syndrome Compared to Electrodiagnostics

Abstract

Background The combined sensory index (CSI) is the most sensitive electrodiagnostic criteria for carpal tunnel syndrome (CTS), and the CSI and Bland criteria have been shown to predict surgical treatment outcomes. The proposed ultrasound measurements have not been assessed against the CSI for diagnostic accuracy and grading of CTS severity. Objective To investigate the use of ultrasound evaluations for both diagnosis and assessment of severity grading of CTS in comparison to electrodiagnostic assessment. Design All patients underwent an electrodiagnostic evaluation using the CSI and Bland severity grading. Each patient underwent an ultrasound evaluation including cross‐sectional area (CSA), the change in CSA from the forearm to the tunnel (∆CSA), and the wrist‐forearm ratio (WFR). These measurements were assessed for diagnostic and severity grading accuracy using the CSI as the gold standard. Setting Tertiary academic center. Participants All patients referred for electrodiagnostic evaluation for CTS were eligible for the study. Only those with idiopathic CTS were included and those with prior CTS treatment were also excluded. Ninety‐five patients were included in the study. Interventions Not applicable. Main Outcome Measures The primary study outcome measure was concordance between CSI diagnosis and severity categories and the ultrasound measurements. Both outcomes were also assessed using Bland criteria. Results Optimal cut‐points for diagnosis of CTS were found to be CSA ≥12 mm2, ∆CSA ≥4 mm2, WFR ≥1.4. Using these cut‐points, C‐statistics comparing diagnosis of CTS using ultrasound measurements versus using the CSI ranged from 0.893‐0.966. When looking at CSI severity grading compared to ∆CSA, however, the C‐statistics were 0.640‐0.661 with substantial overlap between severity groups. Conclusions Although ultrasound measurements had high diagnostic accuracy for CTS based on the CSI criteria, ultrasound measurements were unable to adequately distinguish between CSI severity groups among patients with CTS.

Effect of Wrist Dorsiflexion/Palmar Flexion on Median Nerve Deviation and Cross-Sectional Area in Patients with Carpal Tunnel Syndrome

“…In addition, we found that wrist movement also affected the median nerve position shift, and in patients with carpal tunnel syndrome, such position shift was also significantly reduced. This may be because carpal tunnel syndrome is often accompanied by chronic inflammatory hyperplasia of the synovium of the transverse carpal ligament and tendons, which can adhere to the perineurium, resulting in reduced movement and morphological changes of the median nerve [12]. This study found that compared with the control group, there were significant differences in the distance and crosssectional area between the proximal and distal ends of the median nerve in the mild, moderate, and severe groups.…”

“…In addition, we found that wrist movement also affected the median nerve position shift, and in patients with carpal tunnel syndrome, such position shift was also significantly reduced. This may be because carpal tunnel syndrome is often accompanied by chronic inflammatory hyperplasia of the synovium of the transverse carpal ligament and tendons, which can adhere to the perineurium, resulting in reduced movement and morphological changes of the median nerve [ 12 ].…”

The Impact of Reference Standard on Diagnostic Testing Characteristics for Carpal Tunnel Syndrome: A Systematic Review

“…The diagnostic tests evaluated and their weighted mean sensitivity and specificity are outlined in Tables 2 and 3. 16-128 Although studies utilizing “clinical diagnosis” as a reference standard were treated as a unified subset, many studies 16-128 were found to utilize different definitions of clinical diagnosis. An outline of the utilized definitions for “clinical diagnosis” is presented in Supplemental Digital Content 1.…”

The Impact of Rheumatoid Arthritis (RA) in Median Nerve Area in the Wrist Joint: A Case-Control Study

“…USG had high diagnostic accuracy for CTS based on CSI criteria. However, it is unable to distinguish between CSI severity groups [ 6 ]. However, other reviews reported that USG is a reliable imaging modality to diagnose CTS [ 7 ].…”