Value of Grayscale and Power Doppler High‐Resolution Ultrasound in Assessment of Patients with Clinically Suspected Carpal Tunnel Syndrome

Abstract

Objectives-To determine the value of grayscale and power Doppler ultrasound (PDUS) in the evaluation of carpal tunnel syndrome (CTS) in clinically suspected patients.Methods-Eighty-seven wrists of 61 patients with clinically suspected CTS and 57 wrists of 30 healthy control participants were included in our study. Median nerve (MN) cross-sectional area (CSA) measurements were performed at the tunnel inlet level (wCSA) and proximal pronator quadratus muscle level (fCSA). Two parameters were calculated: CSA absolute difference (ΔCSA), which was the difference between the two measurements; and CSA ratio (RCSA), calculated by dividing wCSA over fCSA. The MN at the wrist level was evaluated for hypervascularity with PDUS.Results-The mean wCSA, R-CSA, and ΔCSA values were significantly higher in patients (17 mm 2 , 2.45, and 9.9 mm 2 , respectively) than in control participants (8 mm 2 , 1.29, and 1.65 mm 2 ; (P < .0001). At their corresponding cutoff values, the wCSA yielded higher sensitivity (95%) and lower specificity (88%) compared to the RCSA and ΔCSA (89% and 93% sensitivity and 93% and 89% specificity). Power Doppler US was the most specific US parameter (100%) but the least sensitive (76%). A multivariate logistic regression model including the wCSA, RCSA, and PDUS yielded 97% diagnostic accuracy at their optimal cutoffs, which increased to 99% after eliminating age and body mass index confounding effects.Conclusions-The combination of MN swelling measurements and PDUS increases the diagnostic accuracy of US in patients with clinically suspected CTS.

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

“…We found the optimal cutoff for ∆CSA was ≥4 mm 2 for sensitivity of 95.2% and specificity of 93.8%‐95.3%, and the optimal WFR ≥1.4 for the sensitivity of 95.2% and specificity of 84.4%‐87.5% at all three locations. These findings are similar to those by Mhoon et al 22 and Gamil et al 9 Both ∆CSA and WFR had a higher diagnostic accuracy than CSA, likely because both ∆CSA and WFR minimize the influence of individual anthropomorphic variations. Because ∆CSA had the highest concordance, we focused on that measurement for our analysis of severity grading.…”

“…Ultrasound is rapid and noninvasive, causes no patient discomfort, and can provide detailed and dynamic anatomic information. Several ultrasound parameters have been proposed to have high diagnostic accuracy for CTS such as median nerve cross‐sectional area (CSA), the difference between the CSA measured at the distal forearm (CSA‐PQ) and that measured at the carpal tunnel (∆CSA), and the ratio between the CSA and CSA‐PQ (wrist‐forearm ratio or WFR) 9‐12 . However, there is significant methodological variability that makes it difficult to compare different studies leading to controversy over which measurement is superior and whether there is an ideal location of measurement within the carpal tunnel 10 .…”

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.…”

Systematic Review of the Use of Power Doppler Ultrasound in the Imaging of Peripheral Nerve Compression Neuropathy

“…Almost all control groups consisted of asymptomatic volunteers, predominantly women, although at least a few studies did not provide demographically matched cohorts. 24,29–31…”

“…29,30 Control Group Almost all control groups consisted of asymptomatic volunteers, predominantly women, although at least a few studies did not provide demographically matched cohorts. 24,[29][30][31] Comparator Clinical diagnosis was the reference standard in nine studies, 16,24,27,[31][32][33][38][39][40] and electrophysiologic diagnosis was the reference standard in the rest. Almost all studies compared power Doppler ultrasound with at least one other form of ultrasound, whereas some compared it to electrodiagnostic studies, 7,8,11,13,[20][21][22][23][25][26][27][29][30][31][32][33][34][35][36][37][38][39] magnetic resonance imaging, 25 patient-reported outcomes, 7,20,23,35 or other measures.…”