The diagnostic accuracy of high-resolution ultrasound in screening for carpal tunnel syndrome and grading its severity is moderated by age

Multimodal Deep Learning for Grading Carpal Tunnel Syndrome: A Multicenter Study in China

RATIONALE AND OBJECTIVES

Ultrasound (US)-based deep learning (DL) models for grading the severity of carpal tunnel syndrome (CTS) are scarce. We aimed to advance CTS grading by developing a joint-DL model integrating clinical information and multimodal US features.

MATERIALS AND METHODS

A retrospective dataset of CTS patients from three hospitals was randomly divided into the training (n=680) and internal validation (n=173) sets. An external validation set was prospectively recruited from another hospital (n=174). To further test the model's generalizability, cross-vendor testing was conducted at three additional hospitals utilizing different US systems in the external validation set 2 (n=224). An US-based model was developed to grade CTS severity utilizing multimodal sonographic features, including cross-sectional area [CSA], echogenicity, longitudinal nerve appearance, and intraneural vascularity. A joint-DL model (CTSGrader) was constructed integrating sonographic features and clinical information. Diagnostic performance of both models was verified based on electrophysiological results. In the validation sets, the better-performing model was compared to two junior and two senior radiologists. Additionally, the radiologists' diagnostic performance with artificial intelligence (AI) assistance was evaluated in external validation sets.

RESULTS

CTSGrader achieved areas under the curve (AUCs) of 0.951, 0.910, and 0.897 in the validation sets. The accuracies of CTSGrader were 0.849, 0.833, and 0.827, which were higher than those of US-based model (all p<.05). It outperformed two junior and one senior radiologists (all p<.05) and was equivalent to 1 senior radiologist (all p>.05). With its assistance, the accuracies of two junior and one senior radiologists were improved (all p<.05).

CONCLUSION

The joint-DL model (CTSGrader) developed in our study outperformed the single-modality model. The AI-aided strategy suggested its potential to support clinical decision-making for grading CTS severity.

Combination of morphological and multiparametric MR neurography enhances carpal tunnel syndrome diagnosis and evaluation

This study aimed to investigate the diagnostic and evaluative significance of combining median nerve (MN) morphological measurements with diffusion tensor imaging (DTI) and T2 mapping metrics for carpal tunnel syndrome (CTS). Morphological and multiparametric magnetic resonance neurography (MRN), along with clinical evaluation, were conducted on 33 CTS patients and 32 healthy controls. The MRN metrics included fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), radial diffusivity (RD), T2 value, cross-sectional area (CSA) and MN flattening ratio (MNFR) at both the pisiform bone and hamate bone levels. Differences in MRN metrics between the above two levels (Delta FA, Delta ADC, Delta AD, Delta RD and Delta T2) were calculated. T-tests, multivariable regression, and receiver operating characteristic (ROC) curve analyses were used to compare and classify patients with CTS and controls. The correlations between MRN metrics and clinical characteristics were analyzed. Comparisons were also made between MRN metrics in patients with and without significant symptom improvement after treatment. FA, AD, T2 value, and CSA at the pisiform bone level were identified as independent predictors of CTS. The combination of these metrics improved diagnostic performance (AUC 0.922, sensitivity 84.85% and specificity 90.62%). Delta ADC, Delta AD, and Delta T2 correlated with function Boston scores. The T2 value at hamate bone level, along with Delta AD and FA, correlated with visual analogue score (VAS). CSA and Delta T2 had higher AUCs for classifying patients with and without significant symptom improvement after treatment. These findings suggest that combining MN morphological and multiparametric MRN metrics can enhance the diagnostic performance of CTS and has the potential to provide an objective and quantitative basis for further study of the degree of entrapment and prognosis.

Point of care ultrasound combined with CTS-6 to diagnose idiopathic carpal tunnel syndrome

BACKGROUND

This study aimed to demonstrate the effectiveness of our new diagnostic chart using point of care ultrasound combined with CTS-6 for diagnosing idiopathic carpal tunnel syndrome.

METHODS

We conducted a retrospective analysis of the data of patients who visited our department and received point of care ultrasound combined with CTS-6 from 2020 to 2023. Data regarding age, sex, initial and final diagnosis, cross-sectional area of the median nerve, CTS-6 score, and electrodiagnostic severity were obtained and statistically analyzed.

RESULTS

Of the 177 wrists included in our study, 138 (78 %) were diagnosed with carpal tunnel syndrome, while 39 (22 %) were not (non-carpal tunnel syndrome). With our diagnostic method, 127 wrists (72 %) were diagnosed initially with carpal tunnel syndrome, 23 wrists (13 %) with non-carpal tunnel syndrome, and the rest 27 wrists (15 %) as borderline. Our initial diagnoses of carpal tunnel syndrome and non-carpal tunnel syndrome were maintained in all cases except for two. Cross-sectional area, CTS-6 score, and electrodiagnostic severity showed a positive correlation. A post hoc analysis showed that the new scoring system (CTS-6 score + 2 × cross-sectional area) with a cutoff value of 31.25 points showed a sensitivity as high as 95 % and a specificity of 100 %.

CONCLUSIONS

Our findings suggest that most suspected idiopathic carpal tunnel syndrome cases can be diagnosed correctly using the diagnostic chart. Although additional tools, including electrodiagnostic studies, may be needed for borderline cases, the use of point of care ultrasound combined with CTS-6 may be a recommendable first-line confirmatory test because point of care ultrasound and CTS-6 could be complementary tools, and this chart may be especially beneficial for atypical or outlier cases.

LEVEL OF EVIDENCE

Diagnostic III.

Exploring ultrasound and electromyography for carpal tunnel syndrome diagnosis: a comprehensive comparative study and implications for occupational medicine

Background

To assess the contribution of ultrasound in diagnosing occupational carpal tunnel syndrome (CTS), compare it with electromyography (EMG) results, and evaluate the ultrasound characteristics of CTS patients.

Methods

A nine-month cross-sectional study (January-September 2021) involved CTS patients and a control group, utilizing a structured form for data collection. EMG was performed on the patient group ('cases') and ultrasound examinations were conducted on both groups. Statistical analysis was performed using SPSS software.

Results

Among 44 cases and 30 controls, CTS patients (mean age 44.9 years) exhibited predominantly bilateral symptoms (90.9%). The optimal cross-sectional area (CSA) threshold for diagnosis was 10.3 mm2 (89% sensitivity, 84% specificity). Significant differences in ultrasound criteria were observed between patient and control groups, including the "notch sign" (p = 0.012), hypoechoic appearance (p = 0.016), and reduced median nerve mobility (p = 0.021). Quantitatively, CSA (13.7 mm2 vs. 7.4 mm2), flattening ratio (3.3 vs. 2.1), and retinaculum bulging (3.2 mm vs. 1.9 mm) significantly differed between cases and controls (p = 0.0019, 0.025, and 0.01, respectively). Positive Phalen tests correlated with higher CSA (p = 0.005) and retinacular bulging (p = 0.02). CSA correlated with EMG parameters, indicating slower conduction velocities, lower amplitudes, and longer latencies (p < 10^(-3), r = -0.56, -0.62, -0.36, and -0.68, respectively).

Conclusion

This study highlights ultrasound's diagnostic potential for CTS, particularly in occupational settings. Its non-invasiveness and reliability advocate for its integration into routine diagnostic protocols, supporting evidence-based management strategies. Further research is needed to explore long-term efficacy and broader applicability.

Association between electrodiagnosis and neuromuscular ultrasound in the diagnosis and assessment of severity of carpal tunnel syndrome

BACKGROUND

Neuromuscular ultrasound plays an increasing role in diagnosing carpal tunnel syndrome (CTS). There are limited data supporting the correlation between the electrodiagnostic studies and ultrasound measurements in CTS.

OBJECTIVE

To assess the association between different electrodiagnostic severities and ultrasound measurements of the median nerve in CTS.

DESIGN

A retrospective cohort study.

SETTING

An academic tertiary care center.

PATIENTS

Patients 18 years or older evaluated with upper limb electrodiagnostic studies and neuromuscular ultrasound.

MAIN OUTCOME MEASUREMENT

Ultrasound measurements of the median nerve cross-sectional area (CSA) at the wrist and the calculated wrist-to-forearm ratio (WFR) were compared with the electrodiagnostic severity (normal, mild, moderate, and severe). Mean analysis and analysis of variance test (α = 0.05) were performed to assess the association.

RESULTS

A total of 1359 limbs were identified. There was a statistically significant association between electrodiagnostic severity of CTS and median nerve CSA at the wrist (p < .001), as well as the WFR (p < .001). The mean median nerve CSA at the wrist and WFR were 7.01 ± 2.06 mm2 (95% CI: 6.80-7.20) and 1.24 ± 0.36 (95% CI: 1.16-1.24) in electrodiagnostically normal median nerves, 10.47 ± 2.82 mm2 (95% CI: 10.25-10.75) and 2.06 ± 0.67 (95% CI: 2.04-2.16) in electrodiagnostically mild CTS, 12.95 ± 4.74 mm2 (95% CI: 12.41-13.59) and 2.49 ± 1.04 (95% CI: 2.37, 2.63) in electrodiagnostically moderate CTS, and 14.69 ± 5.38 mm2 (95% CI: 13.95-15.44) and 2.71 ± 1.02 (95% CI: 2.56-2.84) in electrodiagnostically severe CTS, respectively.

CONCLUSION

This study suggests a direct association between electrodiagnostic severity and ultrasound measurements of the median nerve in patients with suspected CTS.

The relationship between ultrasound and electrodiagnostic findings in relation of the severity of carpal tunnel syndrome

INTRODUCTION

Carpal tunnel syndrome is the most common compression neuropathy. Grading the severity of carpal tunnel syndrome is an important factor in deciding on the type of treatment. This study aims to determine the relationships between the findings of the electrodiagnosis and ultrasonography methods based on the severity of carpal tunnel syndrome.

METHODS

In this prospective clinical study, 50 patients (96 wrists) who were referred to the Physical Medicine and Rehabilitation Department of the Shohada Tajrish Hospital, Tehran, Iran (from March 2021 to November 2022) were studied. All patients with a history and clinical examination related to CTS underwent electrodiagnosis studies. Based on the results of electrodiagnosis, patients were divided into three groups: mild, moderate, and severe. All eligible patients underwent ultrasound at the cross-section of the wrist (at the level of the pisiform bone, the entrance of the canal) and the middle of the forearm.

RESULTS

In this study, the cross-sectional area of the median nerve was measured in 96 wrists of 50 patients with a mean age of 51.78 ± 9.80 years. The mean CSA of the median nerve in the mild, moderate, and severe groups was reported as 0.12 ± 0.03, 0.14 ± 0.02, and 0.21 ± 0.06, respectively. The mean WFR in different groups of CTS was reported as 1.85 ± 0.56, 1.93 ± 0.56, and 2.45 ± 0.49, respectively. A significant relationship between ultrasound findings, including CSA-inlet and WFR, and electrodiagnosis findings was presented (P value < 0.05).

CONCLUSION

Based on our findings, there is a statistically significant relationship between the sonographic findings, including the mean CSA-inlet and WFR, and the severity of CTS based on the electrodiagnosis study. Our findings revealed that as disease severity increases, sonographic parameters also increase significantly.

Diagnostic meta-analysis of the efficacy of ultrasonography for diagnosing carpal tunnel syndrome: A comparison between Asian and non-Asian populations

BACKGROUND

Ultrasonography is used to diagnose carpal tunnel syndrome (CTS) according to various criteria. This diagnostic meta-analysis aimed to evaluate the efficacy of ultrasonography for diagnosing CTS, focusing on the cross-sectional area (CSA) of the median nerve (MN) at the inlet of the carpal tunnel and regional variations in diagnostic thresholds between Asian and non-Asian populations.

METHODS

A comprehensive literature search was conducted using PubMed, Embase, and the Cochrane Library. The risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). Patient demographic data, diagnostic "gold standards", CSA cutoff values, and diagnostic results were extracted. Meta-analysis was performed to determine the sensitivity, specificity, and optimal CSA cutoff values.

RESULTS

For the 25 included studies, a combined sensitivity of 88% and specificity of 84% for CSA measurements at the carpal tunnel inlet were obtained. The Asian group had a sensitivity of 84% and specificity of 86%, while the non-Asian group had a sensitivity of 91% and specificity of 82%. The mean CSA in the Asian group was significantly lower than that in the non-Asian group (12.93 mm2 and 14.77 mm2, respectively; p = 0.042). For the Asian group, the summary receiver operating characteristic curve had an area under the curve (AUC) of 0.92 with an optimal cutoff of 10.5 mm2; for the non-Asian group, an AUC of 0.94 was obtained with a cutoff of 11.5 mm2.

CONCLUSION

Ultrasonography is a reliable diagnostic method for CTS, with distinct optimal cutoff values observed between Asian and non-Asian populations. Therefore, population-specific diagnostic criteria for CTS are recommended.

Application of radiomics model based on ultrasound image features in the prediction of carpal tunnel syndrome severity

OBJECTIVE

The aim of our study is to develop and validate a radiomics model based on ultrasound image features for predicting carpal tunnel syndrome (CTS) severity.

METHODS

This retrospective study included 237 CTS hands (106 for mild symptom, 68 for moderate symptom and 63 for severe symptom). There were no statistically significant differences among the three groups in terms of age, gender, race, etc. The data set was randomly divided into a training set and a test set in a ratio of 7:3. Firstly, a senior musculoskeletal ultrasound expert measures the cross-sectional area of median nerve (MN) at the scaphoid-pisiform level. Subsequently, a recursive feature elimination (RFE) method was used to identify the most discriminative radiomic features of each MN at the entrance of the carpal tunnel. Eventually, a random forest model was employed to classify the selected features for prediction. To evaluate the performance of the model, the confusion matrix, receiver operating characteristic (ROC) curves, and F1 values were calculated and plotted correspondingly.

RESULTS

The prediction capability of the radiomics model was significantly better than that of ultrasound measurements when 10 robust features were selected. The training set performed perfect classification with 100% accuracy for all participants, while the testing set performed accurate classification of severity for 76.39% of participants with F1 values of 80.00, 63.40, and 84.80 for predicting mild, moderate, and severe CTS, respectively. Comparably, the F1 values for mild, moderate, and severe CTS predicted based on the MN cross-sectional area were 76.46, 57.78, and 64.00, respectively..

CONCLUSION

This radiomics model based on ultrasound images has certain value in distinguishing the severity of CTS, and was slightly superior to using only MN cross-sectional area for judgment. Although its diagnostic efficacy was still inferior to that of neuroelectrophysiology. However, this method was non-invasive and did not require additional costs, and could provide additional information for clinical physicians to develop diagnosis and treatment plans.

The Diagnostic Utility of Ultrasound and Electrodiagnostic Studies in The Young and Old

Purpose

Carpal tunnel syndrome is the most common compressive neuropathy. The diagnostic parameters currently used for the general adult population may not be valid in elderly or younger cohorts. The purpose of this study is to determine the diagnostic accuracy of nerve conduction studies (NCS) and ultrasound (US) in different age groups utilizing the 6-item Carpal tunnel syndrome (CTS) symptoms scale (CTS-6) as the reference standard.

Methods

A retrospective database of patients who underwent US and NCS as part of the diagnostic work-up for suspected peripheral nerve compression was reviewed. Subjects were separated into three groups based on the median age of carpal tunnel syndrome patients (55 years of age) and two standard deviations (standard deviation 13.5 years) above and below the median. The young group was 28 years of age or less, the middle group was 29-71 years of age, and the old group was 72 years of age or greater. CTS-6 and Boston Carpal Tunnel Syndrome Questionnaire scores were recorded. Using CTS-6 as a reference standard, the sensitivity and specificity were calculated for NCS and US.

Results

A total of 295 hands were included in the analysis with 23 hands in the young group and 24 hands in the old group. NCS showed 31% sensitivity and 100% specificity in the young group compared to 54% sensitivity and 90% specificity for US. NCS showed 94% sensitivity and 25% specificity in the old group compared to 81% sensitivity and 38% specificity for US. Overall accuracy for US and NCS was 66% for both tests when looking at all age groups. The accuracy in the young group was 70% for US and 61% for NCS, whereas the accuracy in the old group was 67% for US and 71% for NCS.

Conclusions

US has comparable sensitivity and specificity to NCS in patients two or more standard deviations above or below the mean age for presentation of CTS. US may be more accurate in younger patients, although NCS limits the number of false positive tests. There remains a substantial amount of inaccuracy for both tests when using a validated clinical diagnostic tool (CTS-6) as the reference standard.

Type of study/level of Evidence

Diagnostic IV.

The Application of Ultrasound Image-Based Radiomics in the Diagnosis of Mild Carpal Tunnel Syndrome

OBJECTIVES

The ultrasound diagnosis of mild carpal tunnel syndrome (CTS) is challenging. Radiomics can identify image information that the human eye cannot recognize. The purpose of our study was to explore the value of ultrasound image-based radiomics in the diagnosis of mild CTS.

METHODS

This retrospective study included 126 wrists in the CTS group and 88 wrists in the control group. The radiomics features were extracted from the cross-sectional ultrasound images at the entrance of median nerve carpal tunnel, and the modeling was based on robust features. Two radiologists with different experiences diagnosed CTS according to two guidelines. The area under receiver (AUC) operating characteristic curve, sensitivity, specificity, and accuracy were used to evaluate the diagnostic efficacy of the two radiologists and the radiomics model.

RESULTS

According to guideline one, the AUC values of the two radiologists for CTS were 0.72 and 0.67, respectively; according to guideline two, the AUC were 0.73 and 0.68, respectively. The radiomics model achieved the best accuracy when 16 important robust features were selected. The AUC values of training set and test set were 0.92 and 0.90, respectively.

CONCLUSIONS

The radiomics label based on ultrasound images had excellent diagnostic efficacy for mild CTS. It is expected to help radiologists to identify early CTS patients as soon as possible, especially for inexperienced doctors.

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

Lack of a reliable reference standard for carpal tunnel syndrome (CTS) diagnosis could impact the diagnostic test characteristics. This systematic review sought to evaluate differences in the accuracy of CTS diagnostic modalities based on the reference standard used.

Methods

A systematic review was performed following PRISMA guidelines to investigate diagnostic modalities used in CTS. A literature search of Embase, PubMed, and Cochrane Reviews was conducted for the years of 2010-2021 for primary data, and 113 studies met final inclusion criteria. Studies were stratified based on the reference standard utilized and diagnostic modality assessed, and the weighted means of the sensitivities and specificities were calculated.

Results

Thirty-five studies used clinical diagnosis alone as a reference standard, and 78 studies used electrodiagnostic study (EDS). The specificity for MRI and ultrasound (US) were substantially lower when EDS was used as the reference standard. MRI was the test most affected by the reference standard used, showing increased sensitivity when using EDS as the reference compared to clinical diagnosis (77.1% versus 60.9%) and decreased specificity (87.6% versus 99.2%). Regardless of the reference standard used, all tests had anticipated false-positive and/or false-negative rates of at least 10%.

Conclusions

Testing characteristics vary greatly based on the choice of reference standard, with the sensitivity of MRI most affected. Regardless of reference standard used, EDS, US, and MRI each had false-positive and/or false-negative rates too great to be appropriate for use as a screening examination.

Pathophysiology, Diagnosis, Treatment, and Genetics of Carpal Tunnel Syndrome: A Review

Carpal tunnel syndrome (CTS) is a common peripheral canalicular nerve entrapment syndrome in the upper extremities. The compression of or injury to the median nerve at the wrist as it passes through a space-limited osteofibrous carpal canal can cause CTS, resulting in hand pain and impaired function. The present paper reviews the literature on the prevalence, pathology, diagnosis, treatment, and risk factors of CTS in conjunction with the role of genetic factors in CTS etiology. CTS diagnosis is primarily linked with clinical symptoms; still, it is simplified by sophisticated approaches such as magnetic resonance imaging and ultrasonography. CTS symptoms can be ameliorated through conservative and surgical strategies. The exact CTS pathophysiology needs clarification. Genetic predispositions to CTS are augmented by various variants within genes; however, CTS etiology could include risk factors such as wrist movements, injury, and specific conditions (e.g., age, body mass index, sex, and cardiovascular conditions). The high prevalence of CTS diminishes the quality of life of its sufferers and imposes costs on health systems, hence the significance of research and clinical trials to elucidate CTS pathogenesis and develop novel therapeutic targets.

Median nerve ultrasound cross sectional area and wrist-to-forearm ratio in relation to carpal tunnel syndrome related axonal damage and patient age

Objective

Primary objective was to retrospectively examine the effects of patient age and carpal tunnel syndrome (CTS) related axon loss on median nerve (MN) high resolution ultrasound (HRUS) in younger and older patients. HRUS parameters evaluated in this study were MN cross sectional area at the wrist (CSA) and wrist-to-forearm ratio (WFR).

Methods

The material comprised 467 wrists of 329 patients. The patients were categorized into younger (<65 years) and older (≥65 years) groups. Patients with moderate to extreme CTS were included in the study. Axon loss of the MN was assessed by needle EMG and graded by the interference pattern (IP) density. The association between axon loss and CSA and WFR was studied.

Results

The older patients had smaller mean CSA and WFR values compared to the younger patients. CSA correlated positively to the CTS severity only in the younger group. However, WFR correlated positively to CTS severity in both groups. In both age groups, CSA and WFR correlated positively with IP reduction.

Conclusions

Our study complemented recent findings on the effects of patient age on the CSA of the MN. However, although the MN CSA did not correlate with the CTS severity in older patients, the CSA increased in respect to the amount of axon loss. Also, as a new result, we presented the positive association of WFR with CTS severity among older patients.

Significance

Our study supports the recently speculated need for different MN CSA and WFR cut-off values for younger and older patients in assessing the severity of CTS. With older patients, WFR may be a more reliable parameter to assess the CTS severity than the CSA. CTS related axonal damage of the MN is associated to additional nerve enlargement at the carpal tunnel intel site.

Image analysis can reliably quantify median nerve echogenicity and texture changes in patients with carpal tunnel syndrome

OBJECTIVE

To study the ability of image analysis measures to quantify echotexture changes of median nerve in order to provide a complementary diagnostic tool in CTS.

METHODS

Image analysis measures (gray level co-occurrence matrix (GLCM), brightness, hypoechoic area percentage using max entropy and mean threshold) were calculated in normalized images of 39 (19 younger and 20 older than 65y) healthy controls and 95 CTS patients (37 younger and 58 older than 65y).

RESULTS

Image analysis measures were equivalent or superior (older patients) to subjective visual analysis. In younger patients, GLCM measures showed equivalent diagnostic accuracy with cross sectional area (CSA) (Area Under Curve (AUC for inverse different moment = 0.97). In older patients all image analysis measures showed similar diagnostic accuracy to CSA (AUC for brightness = 0.88). Moreover, they had abnormal values in many older patients with normal CSA values.

CONCLUSIONS

Image analysis reliably quantifies median nerve echotexture alterations in CTS and offers similar diagnostic accuracy to CSA measurement.

SIGNIFICANCE

Image analysis may offer added value to existing measures in the evaluation of CTS, especially in older patients. Its clinical implementation would require incorporation of mathematically simple software code for online nerve image analysis in ultrasound machines.

Shear wave elastography is a valuable tool for diagnosing and grading carpal tunnel syndrome

OBJECTIVE

To quantify the shear velocity and stiffness of the median nerve (MN) with shear wave elastography (SWE) at the carpal tunnel entrance and determine whether SWE is useful for diagnosing and staging carpal tunnel syndrome (CTS).

MATERIALS AND METHODS

The study included 58 patients (79 wrists) with clinical and electroneuromyographic diagnoses of CTS and 55 healthy controls (63 wrists). MN shear velocity and stiffness were measured by SWE on the axial plane in both groups. The differences between CTS patients and controls and between different grades of CTS based on electrodiagnostic tests were studied using Student's t test and ANOVA with ROC analysis.

RESULTS

The mean MN shear velocity and stiffness were significantly greater in CTS patients (2.5 ± 0.37 m/s and 19.4 ± 5.8 kPa) than in controls (1.91 ± 0.24 m/s and 11.1 ± 3.0 kPa) (p < 0.001) and greater in the severe CTS group (2.69 ± 0.39 m/s and 22.4 ± 7.1 kPa) than in the mild CTS group (2.37 ± 0.35 m/s and 17.3 ± 4,8 kPa). The cutoff value for the shear velocity was 2.13 m/s, with 86% and 82% sensitivity and specificity, respectively, and the cutoff value for stiffness was 13.6 kPa, with 87% and 82% sensitivity and specificity.

CONCLUSION

MN shear velocity and stiffness are significantly higher in CTS patients. SWE can be used to diagnose CTS and distinguish between patients with mild and severe disease.

Ultrasonography for the diagnosis of carpal tunnel syndrome: correlation of clinical symptoms, cross-sectional areas and electroneuromyography

This study evaluates the usefulness of ultrasonography in diagnosing carpal tunnel syndrome (CTS). The cross-sectional area of the median nerve was measured at the forearm and its entry into the carpal tunnel and compared with clinical symptoms and electroneuromyography. A total of 124 patients were examined, 77 patients with clinically confirmed CTS and 47 controls. A significant correlation was found between the ultrasonography cross-sectional area values at entry points into the carpal tunnel and electroneuromyography. The highest sensitivity (87%) and specificity (91%) for different cut-off values (8.5-12.5 mm²) of the cross-sectional area was for 11.5 mm². The use of ultrasonography may provide a quick and reliable differential diagnostic tool for the primary diagnosis of CTS in patients with classical symptoms.Level of evidence: II.

Sonographic evaluation of the abductor pollicis brevis muscle reflects muscle strength recovery after carpal tunnel release

PURPOSE

This study aimed to examine the associations between sonographic measurements of the abductor pollicis brevis (APB), grip and pinch strength, and distal motor latency (DML) in patients with carpal tunnel syndrome (CTS) before and after surgery.

METHODS

We prospectively studied patients (46 hands) who underwent 1 year of postoperative follow-up after endoscopic carpal tunnel release. The patients underwent ultrasound (US) scans, grip and pinch strength assessment, a nerve conduction study, and patient-reported outcome measures (Carpal Tunnel Syndrome Instrument and Michigan Hand Outcomes Questionnaire) before and 1 year after surgery. The standardized response mean was calculated to compare the sensitivity of clinical changes in these measurements.

RESULTS

US measurements (thickness of the APB and the cross-sectional area of the APB) and muscle strength (grip strength, key pinch, and tip pinch) were greater, and DML was reduced after surgery compared with those before surgery (all P < 0.05). Patient-reported outcome measures also showed clinical improvement 1 year after surgery (P < 0.05). US measurements of the APB were significantly correlated with grip and pinch strength (all P < 0.05), but not with DML, before surgery and 1 year after surgery. The standardized response mean showed a large responsiveness for US measurements of the APB and patient-reported outcome measures.

CONCLUSION

US evaluation of the APB after CTS can complement the evaluation of grip and pinch strength in the clinical setting. Postoperative recovery of the APB leads to improved motor dysfunction in CTS. Therefore, US measurement of the APB could be a useful tool for evaluating motor function.

Application of digital infrared thermography for carpal tunnel syndrome evaluation

We investigated the thermographic findings of carpal tunnel syndrome (CTS). We enrolled 304 hands with electrodiagnostically identified CTS and 88 control hands. CTS hands were assigned to duration groups (D1, < 3 months; D2, 3‒6 months; D3, 6‒12 months; D4, ≥ 12 months) and severity groups (S1, very mild; S2, mild; S3, moderate; S4, severe). The temperature difference between the median and ulnar nerve territories (ΔM-U territories) decreased as CTS duration and severity increased. Significant differences in ΔM-U territories between the D1 and D3, D1 and D4, D2 and D4, and S1 and S4 groups (P = 0.003, 0.001, 0.001, and < 0.001, respectively) were observed. Thermal anisometry increased as CTS duration and severity increased. Significant differences in thermal anisometry between the D1 and D4 as well as the D2 and D4 groups (P = 0.005 and 0.04, respectively) were noted. Thermal anisometry was higher in the S4 group than in the S1, S2, and S3 groups (P = 0.009, < 0.001, and 0.003, respectively). As CTS progresses, skin temperature tends to decrease and thermal variation tends to increase in the median nerve-innervated area. Thermographic findings reflect the physiological changes of the entrapped median nerve.

Diagnosis of Carpal Tunnel Syndrome using Shear Wave Elastography and High-frequency Ultrasound Imaging

OBJECTIVES

The performance of ultrasound features from shear wave elastography (SWE) and high-frequency ultrasound imaging was evaluated independently and in combination to diagnose carpal tunnel syndrome (CTS).

MATERIALS AND METHODS

Twenty-five subjects were imaged in a sitting position with an arm extended and palm facing up. SWE of the medial nerve (MN) was acquired at the wrist level (site 1) and proximal to the pronator quadratus muscle (site 2). Cross-sectional area (CSA) and vascularity of the MN were assessed at the wrist using a 24 MHz probe. Color and power Doppler imaging (CDI and PDI), monochrome and color-coded Superb Microvascular Imaging (SMI) were performed for vascularity assessments. The diagnosis and severity of CTS was determined by clinical and electrodiagnostic tests. Diagnostic performance of the ultrasound features was assessed by t-tests, ANOVAs, and ROC analysis.

RESULTS

The study included 20 control hands and 27 hands with CTS. All ultrasound features except for the stiffness ratio were significantly different between the CTS and control wrists (p<0.04). The stiffness of MN at site 1 showed a higher accuracy than at site 2. The combination of CSA and MN stiffness from site 2 showed an overall accuracy of 95% with a specificity and sensitivity of 100% and 93%, respectively. The CSA, MN stiffness from site 2, and CDI combination improved the accuracy to 96% with specificity and sensitivity of 100% and 93%, respectively. However, no ultrasound features (independently or in combination) differentiated all stages of CTS severity.

CONCLUSIONS

SWE with high-frequency ultrasound imaging showed potential for the diagnosis of CTS.

Sonographic pattern of median nerve enlargement in Hansen's neuropathy

OBJECTIVES

Median nerve enlargement in leprosy seems to be more proximal than in carpal tunnel syndrome (CTS), but this feature has not been studied systematically. The aim of the study was to compare the sites of median nerve enlargement in patients with leprosy with that of patients with CTS.

MATERIALS AND METHODS

Transverse sections of the median nerve were recorded from wrist to the mid-forearm (at distal wrist crease and at 2-cm: M1, 4-cm: M2, 6-cm: M3, 8-cm: M4 and 10-cm: M5, proximal to the distal wrist crease in the forearm) in patients with leprosy, CTS and healthy subjects using high-resolution ultrasound.

RESULTS

Twenty-six patients each with leprosy and CTS were compared with healthy controls. Patients with leprosy included 6 (23.1%), 7 (26.9%), 7 (26.9%) and 6 (23.1%) patients with borderline tuberculoid, borderline-borderline, borderline lepromatous and lepromatous leprosy, respectively. Cross-sectional area (CSA) of median nerve was increased in all patients with leprosy as compared to healthy controls at all points of measurement. CSA was higher among patients with leprosy as compared to CTS at all points except at the wrist. In patients with leprosy, the maximal enlargement was noted 2-cm (M1) proximal to the wrist crease with gradual tapering of the CSA proximally (p < .05). In contrast, in patients with CTS the median nerve was maximally enlarged at the distal wrist crease (p<.05).

CONCLUSIONS

Median nerve enlargement 2-cm proximal to the distal wrist crease distinguishes leprosy from CTS. This important discriminating sign can be used at point-of-care to identify patients with leprosy.

The Neurophysiological Severity of Carpal Tunnel Syndrome Cannot Be Predicted by Median Nerve Cross-Sectional Area and Wrist-to-Forearm Ratio

PURPOSE

The median nerve cross-sectional area at the wrist (CSA) and the wrist-to-forearm ratio of the cross-sectional areas (WFR) are ultrasound parameters used in the diagnosis and grading of carpal tunnel syndrome. This study aimed to determine the diagnostic accuracy of the CSA and WFR as well as to compare their diagnostic value.

METHODS

A retrospective evaluation was conducted of a cohort of 218 patients who had undergone nerve conduction studies (NCSs) and an ultrasound of the median nerve. The examined wrists were classified into an NCS negative and three NCS positive (mild, moderate, and severe) categories. The CSA and WFR were compared across the categories.

RESULTS

The CSA and WFR were significantly smaller in the NCS negative category than in the NCS positive categories. The WFR was significantly smaller in the mild category than in the moderate category. The CSA could not be used to differentiate across the NCS positive categories.

CONCLUSIONS

The CSA and WFR are satisfactorily reliable in detecting carpal tunnel syndrome, but they cannot be considered as surrogate indicators of electrophysiological severity.

Reduction in median nerve cross-sectional area at the forearm correlates with axon loss in carpal tunnel syndrome

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The median nerve CSA at the forearm is smaller when CTS is involved with axon loss.

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WFR of the median nerve is highest when CTS causes slight axon loss.

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Axon loss of the median nerve in CTS hampers the diagnostic value of wCSA and WFR.

Objective

To explore the relationship between axon loss and measured cross-sectional areas of the median nerve (MN) in severe carpal tunnel syndrome (CTS).

Methods

In this retrospective study of 158 examined wrists, we compared axon loss to the ultrasound parameters MN cross-sectional area at the wrist (wCSA), MN cross-sectional area at the forearm (fCSA) and wrist-to-forearm ratio (WFR), in patients with moderate to extreme CTS. Axon loss was evaluated by needle electromyography (EMG) of the abductor pollicis brevis muscle (spontaneous activity and reduction of interference pattern).

Results

Both the spontaneous activity and interference pattern reduction correlated negatively to fCSA (r = −0.189, p = 0.035; r = −0.210, p = 0.019; respectively). In moderate CTS, both the spontaneous activity and interference pattern reduction correlated positively to WFR (r = 0.231, p = 0.048; r = 0.232, p = 0.047; respectively). The WFR was highest when slight spontaneous activity was detected. Neither wCSA nor WFR correlated with axon loss in severe and extreme CTS.

Conclusions

The fCSA is smaller when axon loss in CTS is more prominent. The WFR is highest when CTS is associated with slight axon loss of the MN.

Significance

CTS might cause retrograde axonal atrophy detected as small fCSA. Prominent axon loss in CTS may reduce the diagnostic value of WFR.

Quantitative Models for Prediction of Cumulative Trauma Disorders Applied to the Maquiladora Industry

Temperature gradient changes on the surface of the skin or in the middle of the body are signs of a disease. The aim of this study is to develop quantitative models for the prediction of cumulative trauma disorders (CTDs) arising from highly repetitive activities, considering risk factors, such as age, gender, body mass index (BMI), blood pressure (BP), respiratory rate (RR), and heart rate, to prevent injuries in manufacturing factory operators. This research involved 19 individuals from the area of sanding and 14 individuals from the area of tolex in manufacturing factories who had their vital signs and somatometry taken, as well as thermal images of their hands in the dorsal and palmar areas; an evaluation by the OCRA method was also applied. Factors such as BP and heart rate were determined to significantly influence the injuries, but no strong association with BMI was found. Quadratic regression models were developed, the estimates of which were adequately adjusted to the variable (R² and R² adjusted > 0.70). When integrating the factors of the OCRA method to the generated models, a better fit was obtained (R² and adjusted R² > 0.80). In conclusion, the participants who present levels out of the normal range in at least one of the factors have high probabilities of developing injuries in their wrists.

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

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.

Cross-sectional area reference values of the median nerve at the palm using ultrasound

BACKGROUND

The most common neuromuscular ultrasound abnormality in carpal tunnel syndrome is enlargement of the median nerve near the distal wrist crease, but sometimes the median nerve enlarges in the palm, just distal to the transverse carpal ligament. This study was conducted to devise a protocol for measuring the median nerve in the palm and to generate reference values for nerve cross-sectional area at this site.

METHODS

A systematic protocol was developed, 30 healthy individuals underwent ultrasound of the median nerve in the palm bilaterally, and cross-sectional area was recorded.

RESULTS

The mean cross-sectional area of the median nerve at the palm was between 11.4 mm² (95% confidence interval [CI] [10.4,12.4]) and 11.6 mm² (95%CI [10.6,12.6]).

CONCLUSIONS

The median nerve can be measured just distal to the hook of the hamate in the palm, and the mean cross-sectional area at this site is slightly larger than it is at the distal wrist crease.

A Review of Carpal Tunnel Syndrome and Its Association with Age, Body Mass Index, Cardiovascular Risk Factors, Hand Dominance, and Sex

Carpal tunnel syndrome (CTS) is one of the most common compressive, canalicular neuropathies of the upper extremities, causing hand pain and impaired function. CTS results from compression or injury of the median nerve at the wrist within the confines of the carpal tunnel. Parameters such as age, sex, and body mass index (BMI) could be risk factors for CTS. This research work aimed to review the existing literature regarding the relationship between CTS and possible risk factors, such as age, sex, BMI, dominant hand, abdominal circumference, respiratory rate, blood pressure, and cardiac rate to determine which ones are the most influential, and therefore, take them into account in subsequent applied research in the manufacturing industry. We performed a literature search in the PubMed, EBSCO, and ScienceDirect databases using the following keywords: carpal tunnel syndrome AND (age OR sex OR BMI OR handedness OR abdominal circumference OR respiratory rate OR blood pressure OR cardiac rate). We chose 72 articles by analyzing the literature found based on selection criteria. We concluded that CTS is associated with age, female sex, and high BMI. Trends and future challenges have been proposed to delve into the relationship between risk factors and CTS, such as correlation studies on pain reduction, analysis of weight changes to predict the severity of this pathology, and its influence on clinical treatments.