Determination of Electrophysiologically Moderate and Severe Carpal Tunnel Syndrome: Ultrasonographic Measurement of Median Nerve at the Wrist

A "Clear" Carpal Tunnel Syndrome Diagnosis on Ultrasound Examination Does Not Predict Improved Outcomes When Compared With a "Borderline" Diagnosis

BACKGROUND

Nerve conduction studies (NCS) and ultrasound (US) remain imperfect compared with clinical diagnosis and/or diagnostic tools such as carpal tunnel syndrome-6 (CTS-6) for diagnosis of carpal tunne syndrome (CTS). One potential reason for the discrepancy between clinical diagnosis and testing is "borderline" case inclusion. This study aims to compare clinical outcomes after carpal tunnel release (CTR) between "borderline" and "clear" patients with CTS determined by NCS and US.

METHODS

This was a retrospective review of patients who underwent CTR. We collected NCS and US measurements of the median nerve cross-sectional area (MNCSA) at the carpal tunnel inlet, and the Boston Carpal Tunnel Questionnaire (BCTQ) scores comprised of the Symptom Severity Scale (SSS) and the Functional Status Scale (FSS). Ultrasound measurements defined patients as having "borderline" (MNCSA < 13 mm2) or "clear" (MNCSA ≥ 13 mm2) CTS.

RESULTS

The study included 94 unilateral patients with CTS. "Borderline" CTS was diagnosed in 58 patients (62%), and "clear" CTS was diagnosed in 36 patients (38%). No significant differences in BCTQ scores were found between groups. At greater than 6-month follow-up, the mean FSS was 1.44 and 1.45 for clear and borderline groups, respectively (P = .97) and the mean SSS was 1.47 and 1.51, respectively (P = .84). However, a significant difference between groups when comparing distal motor latency (DML) and distal sensory latency (DSL) existed. The mean DSL was 3.71 and 4.44 for the clear and borderline groups, respectively (P = .02). The mean DML was 4.59 and 5.36 (P = .048).

CONCLUSION

Categorizing CTS diagnosis into "borderline" and "clear" based on preoperative US and NCS testing did not correlate with BCTQ changes after CTR. It remains unclear whether the BCTQ is a valid postoperative assessment tool, despite its frequent use in literature.

[Analysis of the echographic parameters described in the study of carpal tunnel syndrome: A systematic review]

Carpal tunnel syndrome (CTS) is the most common entrapment mononeuropathy; the diagnosis is established by electrodiagnostic tests with until 34% of false positives/negatives. We present the following systematic review which objective is to analyze the most recent literature related to the ultrasound parameters described to study CTS. We selected studies that evaluated ultrasound parameters in patients with clinical suspicion following the Cochrane manual's recommendations. We include systematic reviews, meta-analyses, case-control studies and diagnostic tests, evaluating retrospective studies and bibliographic reviews with proper methodological quality. Articles published between 2005 and 2019. We included eight articles (two systematic reviews/meta-analyses, two case-control studies, one diagnostic test study, two literature reviews, and one retrospective). The parameters analyzed were cross-sectional area, wrist-forearm index, entry-exit index, thinning range, palmar bowing of the flexor retinaculum, and vascularity/mobility. Current evidence allows us to affirm that ultrasound is useful in screening for CTS.

Characteristics of diabetic and non-diabetic carpal tunnel syndrome in terms of clinical, electrophysiological, and Sonographic features: a cross-sectional study

BACKGROUND

Although diabetes is considered a major risk factor for carpal tunnel syndrome (CTS), the characteristics of diabetic CTS have not been fully understood.

OBJECTIVE

This study is aimed at evaluation of the clinical, electrophysiological, and ultrasonographic findings of non-diabetic and diabetic CTS.

METHODS

This retrospective, cross-sectional study included patients diagnosed with CTS. Patient age, sex, involved side, body mass index, clinical and electrophysiological findings, and median nerve cross-sectional area (CSA) were identified. Diabetes was identified through patient or guardian interviews, medical records, and medication history. Linear and binary logistic regression models were established to confirm the associations between the electrophysiological findings, median nerve CSA, and clinical outcomes. Covariates, such as age, sex, body mass index, diabetes, symptom duration, and thenar muscle weakness were adjusted.

RESULTS

Out of the 920 hands, 126 and 794 belonged to the diabetic and non-diabetic CTS groups, respectively. The patients were significantly older in the diabetic CTS group (P < 0.001). The rate of thenar weakness in the diabetic CTS group was also significantly higher than that in the non-diabetic CTS group (P = 0.009). The diabetic CTS group had a more severe electrodiagnostic grade (P = 0.001). The prolonged onset latency of the compound motor nerve action potential (CMAP) and median nerve CSA were well associated with the degree of clinical symptoms. Increased median nerve CSA was significantly associated with prolonged CMAP onset latency (β = 0.64; P = 0.012), prolonged transcarpal latency (β = 0.95; P = 0.044), and decreased CMAP amplitude (β = -0.17; P = 0.002) in the non-diabetic CTS group.

CONCLUSION

Diabetic CTS had more profound electrophysiological abnormalities. Distal motor latency and median nerve CSA were not only associated with each other, but also with clinical symptoms. Further studies are needed to investigate the pathophysiological mechanisms underlying diabetic CTS.

The role of ultrasound in determining the presence and severity of carpal tunnel syndrome in diabetic patients

Carpal tunnel syndrome (CTS) is seen in 5% of the population and 14%-30% in diabetics. Although electrophysiological tests are used as the gold standard method in the diagnosis, alternative methods are being studying. We aimed to investigate whether the measurement of median nerve cross-sectional area (CSA) by ultrasound is associated with the presence and severity of CTS. This prospective, cross-sectional observational study includes 128 randomly selected T2DM patients. Electrodiagnostic study was performed for all patients to diagnose CTS. Median nerve CSA were measured with ultrasound examination. The severity of the CTS was determined by Padua method. Among 128 diabetes mellitus (DM) patients, 54 (28%) had CTS and 53 (41%) had diabetic peripheral polyneuropathy. The mean duration of DM was 11.55 years. Median nerve CSAs of the patients were significantly higher in patients with CTS (CTS (-): 10.47 ± 2.67 vs CTS: (+) 12.37 ± 3.17; p < 0.001). Median nerve CSA cutoff value of >10 mm2 predicts the diagnosis of CTS. However, minimal, mild, and moderate CTS groups had similar CSA according to Padua classification (p > 0.05 for all). CSA measurement with ultrasonography can be used as an effective method in diagnosing severe CTS disease. However, median nerve CSA values should not be used to reveal the severity of CTS, in order not to miss the demonstration of minimal, mild, and moderate groups, as well as being an indicator of only the severe CTS group.

Ultrasound Measurements of the Median Nerve at the Distal Wrist Crease Correlate With Electrodiagnostic Studies

Background: Carpal tunnel syndrome (CTS) is the most common nerve entrapment neuropathy and is commonly evaluated using electrodiagnostic studies (EDSs). Ultrasound (US) has emerged as a potentially easier and more comfortable alternative to EDSs. The purpose of this study is to evaluate whether measurements of the cross-sectional area (CSA) of the median nerve via US correlate with the severity rating of CTS based on EDSs. Methods: A retrospective review of patients aged 18 years or older who underwent US and EDSs of the median nerve for CTS was performed. Sensory nerve action potential, distal motor latency, and compound muscle action potential were measured, and severity was graded on American Association of Neuromuscular and Electrodiagnostic Medicine guidelines. Cross-sectional area of the median nerve was measured via US at the wrist crease. Results: There was a significant association between increasing CSA and increasing EDS severity (P < .0001). The mean CSA for normal, mild, moderate, and severe CTS was 7.48 ± 2.00, 10.36 ± 2.53, 12.01 ± 3.64, and 14.34 ± 4.77 mm2, respectively. The area under the curve demonstrated the ability of median nerve CSA to discriminate between normal and abnormal EDSs with an optimal cutoff CSA of ≥10 mm2, as well as, the ability to discriminate between mild CTS and moderate to severe CTS at a cutoff CSA of greater than or equal to 12 mm2. Conclusions: The results of this study show that US measurements of the median nerve at the distal wrist crease discriminate between normal and abnormal EDSs, and between mild CTS and moderate to severe CTS.

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.

Ultrasonography for the diagnosis of carpal tunnel syndrome: an umbrella review

BACKGROUND

Numerous sonographic modalities and parameters have been used to diagnose carpal tunnel syndrome (CTS), with varying accuracy. Our umbrella review aimed to summarize the evidence from systematic reviews and meta-analyses regarding the use of ultrasound imaging to diagnose CTS.

METHODS

Systematic reviews and meta-analyses meeting the inclusion criteria were searched in PubMed, Embase, Medline, Web of Science, and Cochrane databases from inception to March 2022. Critical appraisal, data extraction, and synthesis were performed in accordance with the criteria for conducting an umbrella review.

RESULTS

Sixteen reviews were included. Three reviews were classified as high quality, one as moderate, four as low, and eight as critically low. The cross-sectional area (CSA) of the median nerve at the carpal tunnel inlet demonstrated the best reliability and diagnostic accuracy among multiple parameters. A cutoff CSA value of 9-10.5 mm2 gave the highest diagnostic performance in the general population. The degree of CSA enlargement was correlated with CTS severity. Sonoelastography and Doppler ultrasound might provide additional insights into CTS evaluation as median nerve stiffness and vascularity at the wrist were increased in these patients.

CONCLUSIONS

Sonography is a reliable tool to diagnose CTS, with inlet CSA being the most robust parameter. Sonoelastography and Doppler ultrasound can serve as auxiliary tools to confirm CTS diagnoses. Further studies are needed to expand the use of sonography for diagnosing CTS, especially in the presence of concomitant neuromuscular disease(s).

The role of diagnostic ultrasound in the examination of carpal tunnel syndrome: an update and systematic review

BACKGROUND

Diagnostic ultrasound is becoming more available and has potential for identifying carpal tunnel syndrome (CTS), but there is a lack of consensus on optimal measurement parameters and interpretation.

PURPOSE

The purpose of this systematic review was to analyze and summarize recent published data evaluating measurement properties of diagnostic ultrasound for use in individuals with CTS.

METHODS

Five databases were searched to identify studies reporting on diagnostic measurement in individuals ≥18 years of age. Thirty-four studies underwent critical appraisal using Center for Evidence Based Medicine guidelines for diagnostic study accuracy. Each team member independently reviewed and scored the studies and consensus was reached through discussion.

RESULTS

Seventeen studies evaluating 21 unique nerve or tunnel measurements and 9 measurement ratios were included. Measurements of median nerve cross sectional area (CSA) taken at the carpal tunnel inlet consistently demonstrated good to excellent interrater reliability (ICC=0.83-0.93) and good intrarater reliability (r>0.81). All studies supported inlet CSA in differentiating between individuals with and without CTS. Carpal tunnel inlet CSA measurements demonstrated a moderate correlation to the Padua severity classification (r = 0.71), but this varied between studies. Diagnostic accuracy of CSA measured at the carpal tunnel inlet using diagnostic cutoff values ranging from 8.5 mm² to 12.6 mm² resulted in a range sensitivity (63%-96.9%) and specificity (67.9%-100%).

CONCLUSION

The US measurement most supported was the median nerve CSA measured at the carpal tunnel inlet. There was no evidence supporting the routine use of diagnostic US for individuals with suspected CTS, and no additional evidence to support replacement of electrodiagnostic studies by US. More research is needed to determine use of US for classifying CTS severity or as a differential diagnostic tool for conditions that mimic CTS.

LEVEL OF EVIDENCE

N/A.

Difference and ratio of the cross-sectional area of median nerve at the carpal tunnel and the pronator quadratus muscle in diagnosing carpal tunnel syndrome: a cross-sectional study

Background

At present, the most commonly used diagnostic method of carpal tunnel syndrome (CTS) is based on clinical manifestations and electrophysiology, but the electrophysiology is not cheap, invasive, and lacks the presentation of peripheral nerve conditions, which is exactly the advantage of ultrasound (US). The purpose of this study was to evaluate the accuracy and effectiveness of US in the diagnosis of CTS by calculating the cross-sectional area (CSA) at the carpal tunnel and proximally at the level of the pronator quadratus muscle., and to find an appropriate index that can be used to achieve the diagnosis in a more cost-effective manner.

Methods

Forty-three wrists from 35 symptomatic CTS patients and 23 wrists from 18 asymptomatic volunteers were evaluated. Diagnosis in the CTS group was based on the American Academy of Neurology clinical diagnostic criteria. The ultrasonic probe was placed at the carpal tunnel and the distal 1/3 of the pronator muscle respectively, and the carpal tunnel cross-sectional area (CSAC) and the proximal cross-sectional area (CSAP) was calculated, with a further calculation of their difference (ΔCSA) and ratio (R-CSA).

Results

There was a significant difference between the 2 groups regarding mean ± standard deviation (SD) of CSAC, CSAP, ΔCSA, and R-CSA (P<0.01). The cutoff value of 12.14 mm² for CSAC had a sensitivity and specificity of 90.7% and 100%, respectively; the cutoff value of 1.235 mm² for R-CSA had a sensitivity and specificity of 97.67% and 95.65%, respectively; and the cutoff value of 2.035 mm² for ΔCSA had a sensitivity and specificity of 100% and 100%, respectively. Therefore, US was found to be an effective method for the diagnosis of CTS. Receiver operating characteristic curve (ROC) analysis of all patients showed area under the curve (AUC) was 0.9778 for CSAC, 0.9949 for R-CSA and 1.000 for ΔCSA.

Conclusions

US can provide reference values for the diagnosis of CTS. CSAC, ΔCSA, and R-CSA can be used for CTS diagnosis and evaluation. The ROC curve analysis showed that among the 3 values, ΔCSA was the most useful in the diagnosis of patients with CTS. ΔCSA is considered a valid diagnostic value for CTS, as its threshold of 2.04 mm² showed the highest sensitivity and specificity.

Cross-sectional Area Ratio of Median-to-Ulnar and Median-to-Superficial Radial Nerve at the Wrist for Diagnosis of Carpal Tunnel Syndrome

Objectives:

This study aimed to evaluate the diagnostic properties for carpal tunnel syndrome (CTS) of the median-to-ulnar cross-sectional area ratio (MUR) and the median-to-superficial radial cross-sectional area ratio (MRR).

Methods:

A case–control study was conducted. A physiatrist, blinded to the CTS status of the subjects, assessed the cross-sectional area of the median nerve (CSA-m), MUR, and MRR at the distal wrist crease for the CTS and control groups. The relationship of CSA-m, MUR, and MRR with CTS severity was tested using Spearman’s correlation. The overall diagnostic accuracy was determined using the area under the receiver operating characteristic curve (AUC). The cut-off values to diagnose CTS were chosen to achieve similar values for sensitivity and specificity.

Results:

There were 32 hands in the CTS group and 33 hands in the control group. The correlations of CSA-m, MUR, and MRR with CTS severity were 0.66, 0.56, and 0.34, respectively. The AUCs of CSA-m, MUR, and MRR were 0.86 (95%CI: 0.77–0.95), 0.79 (0.69–0.90), and 0.69 (0.56–0.82), respectively. The cut-off values of CSA-m, MUR, and MRR were 12 mm² (sensitivity, 81.3%; specificity, 81.8%), 2.6 (sensitivity, 68.8%; specificity, 69.7%), and 10 (sensitivity, 65.6%; specificity, 63.6%), respectively.

Conclusions

: MUR and MRR had acceptable diagnostic abilities but did not show superiority over CSA-m for CTS diagnosis.

Role of Ultrasonography in Severe Distal Median Nerve Neuropathy

PURPOSE

Electrodiagnostic studies do not differentiate severe lesions of the median nerve in the distal forearm from those within the carpal tunnel when compound muscle action potential over the abductor pollicis brevis and sensory nerve action potential are absent; needle electromyography showing denervation confined to the abductor pollicis brevis is presumed to suggest localization to the carpal tunnel, although the lesion may be in the forearm. Under these circumstances, the patient may undergo carpal tunnel release without benefit. This retrospective study looked at patients with clinical picture of severe carpal tunnel syndrome who had no compound muscle action potential or sensory nerve action potential on median nerve stimulation; the goal was to determine how often ultrasonic imaging pointed to a location other than the carpal tunnel.

METHODS

Patients with clinical picture of severe carpal tunnel syndrome with no sensory nerve action potential and no compound muscle action potential over the abductor pollicis brevis and second lumbrical underwent ultrasonic imaging; criteria for localization to the carpal tunnel included significant increase in the cross-sectional area of the median nerve at the carpal tunnel inlet and increase in the wrist/forearm cross-sectional area ratio.

RESULTS

In 42 of 46 cases, entrapment at the carpal tunnel was confirmed by ultrasonography; in four patients, other causes were located proximal to the carpal tunnel.

CONCLUSIONS

Ultrasonic imaging is useful not only for confirming entrapment of the median nerve at the carpal tunnel in patients with nonlocalizing electrodiagnostic studies but also in detecting pathology in the forearm, which may mimic severe carpal tunnel syndrome.

Estimating the most accurate sonographic measurement in the diagnosis of carpal tunnel syndrome: Which is the best?

Objectives

This study aims to identify the most accurate method or ultrasonographic measurement for the diagnosis of carpal tunnel syndrome (CTS).

Patients and methods

Between October 2010 and April 2011, a total of 160 hands of 87 patients (4 males, 83 females; mean age 54.5 years; range, 26 to 84 years) with clinically and electrodiagnostically proven CTS and 80 hands of 40 controls (3 males, 37 females; mean age 53.7 years; range, 32 to 77 years) were evaluated by sonographic examination. The diameters and cross-sectional areas (CSA) of the median nerve and longitudinal diameters of the median nerve were measured at the inlet, proximal carpal tunnel, and outlet of the carpal tunnel. Volar bulging and thickness of the retinaculum were also measured.

Results

The most optimal combination for the diagnosis of CTS was proximal CSA, volar bulging, and the proximal transverse diameter. The combination of proximal CSA with volar bulging increased the sensitivity and specificity of sonographic measurements.

Conclusion

Based on our study results, ultrasonography can be used as a practical modality to distinguish CTS patients from asymptomatic controls.

Sonographic reference values of median nerve cross-sectional area: a protocol for a systematic review and meta-analysis

BACKGROUND

Median nerve cross-sectional area (CSA) is the primary sonographic parameter for assessing and diagnosing median nerve pathology, such as carpal tunnel syndrome. However, variability in the sensitivity of diagnostic thresholds exists, which may be due to a lack of standardized normative reference values. Current estimates of normal median nerve CSA stem largely from small studies using a local pool of healthy controls. A systematic review and meta-analysis will be conducted to identify all available data for median nerve CSA in healthy, asymptomatic individuals to create a comprehensive set of normative reference values.

METHODS

Articles that include sonographic measures of median nerve CSA will be identified through a rigorous search of published evidence, a hand search through tables of contents of key journals, and the gray literature, including ClinicalTrials.gov and conference abstracts. Each abstract and full text will be reviewed by multiple raters to identify studies from 2000 to present that include original data. Any study that provides median nerve CSA values from healthy individuals will be included (e.g., reference value study, control participants in a diagnostic study). Studies will be assessed for quality using a modified version of the National Institute of Health Study Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies, with primary focus on the use of a detailed and acceptable image acquisition and analysis protocol. Using data from included studies, reference values will be calculated for median nerve CSA by anatomical regions, including the distal forearm, wrist, and carpal tunnel at the level of the pisiform. Reference values will be stratified by gender, ethnicity, and age based upon the specificity of the data provided by the included articles.

DISCUSSION

A comprehensive set of normative reference values of median nerve CSA will reduce variability across studies, allowing future research to more accurately evaluate and establish diagnostic thresholds. Additionally, normative values can serve as a reference for evaluating treatment outcomes and provide a means to investigate and understand minor nuances in CSA changes that may be indicative of preclinical stages of median nerve pathology.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO 2016 CRD42016037286.