Sonography in carpal tunnel syndrome with normal nerve conduction studies

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.

Real-Time Automated Segmentation of Median Nerve in Dynamic Ultrasonography Using Deep Learning

OBJECTIVE

The morphological dynamics of the median nerve across the level extracted from dynamic ultrasonography are valuable for the diagnosis and evaluation of carpal tunnel syndrome (CTS), but the data extraction requires tremendous labor to manually segment the nerve across the image sequence. Our aim was to provide visually real-time, automated median nerve segmentation and subsequent data extraction in dynamic ultrasonography.

METHODS

We proposed a deep-learning model modified from SOLOv2 and tailored for median nerve segmentation. Ensemble strategies combining several state-of-the-art models were also employed to examine whether the segmentation accuracy could be improved. Image data were acquired from nine normal participants and 59 patients with idiopathic CTS.

DISCUSSION

Our model outperformed several state-of-the-art models with respect to inference speed, whereas the segmentation accuracy was on a par with that achieved by these models. When evaluated on a single 1080Ti GPU card, our model achieved an intersection over union score of 0.855 and Dice coefficient of 0.922 at 28.9 frames/s. The ensemble models slightly improved segmentation accuracy.

CONCLUSION

Our model has great potential for use in the clinical setting, as the real-time, automated extraction of the morphological dynamics of the median nerve allows clinicians to diagnose and treat CTS as the images are acquired.

Comparison of Diagnostic Accuracy of Electrodiagnostic Testing and Ultrasonography for Carpal Tunnel Syndrome

BACKGROUND

Confirmatory methods such as electrodiagnostic testing (EDX) and ultrasonography (US) are currently used to support a clinical diagnosis of carpal tunnel syndrome (CTS). Scientific consensus long has preferred nerve conduction studies (NCS); however, recent studies have advocated for a diagnostic niche for ultrasound examination. This study seeks to compare diagnostic accuracies, sensitivity, and specificity between these 2 diagnostic tools.

METHODS

An institutional database was retrospectively analyzed to reveal 402 upper extremity cases (265 patients) with potential for CTS diagnosis. Demographics, NCS results, and US findings were determined for each patient case. Sensitivity and specificity values were determined for each diagnostic modality using Carpal Tunnel Syndrome 6 (CTS-6), a validated clinical CTS scoring system, as the reference standard. Demographic and diagnostic values were compared between positive and negative CTS groups using the 2-tailed t test and χ2 test.

RESULTS

Electrodiagnostic testing resulted in a sensitivity of 87% and a specificity of 27%, whereas US produced a sensitivity of 76% and a specificity of 51%. No statistical difference was found in CTS-6 scores between NCS-positive and NCS-negative patient hands, whereas CTS-6 scores were significantly greater in US-positive CTS cases than US-negative cases (15.2 and 13.1, respectively, P < .001).

CONCLUSIONS

Electrodiagnostic testing yields a greater sensitivity for CTS than US examination. However, US testing aligns more closely with CTS-6 scores and results in a greater specificity and positive predictive value. These findings suggest that US holds a non-trivial niche in CTS diagnosis and that EDX is not clearly preferable for all CTS diagnoses and cases.

Diacutaneous Fibrolysis Intervention in Patients with Mild to Moderate Carpal Tunnel Syndrome May Avoid Severe Cases in Elderly: A Randomized Controlled Trial

BACKGROUND

Carpal Tunnel Syndrome (CTS) mainly affects adults of working age. The prevalence of severe cases is higher in elderly patients (>65 years old). Clinical guidelines recommend conservative treatment as the best option in the initial stages of CTS to avoid severe cases. Diacutaneous Fibrolysis (DF) has demonstrated to improve nerve conduction studies and mechanosensitivity. The main purpose was to quantify changes in the cross-sectional area (CSA) of the median nerve, transversal carpal ligament (TCL) thickness, numbness intensity, and the subjective assessment of clinical change after DF treatment in patients with CTS.

METHODS

a double-blind, randomized, placebo-controlled trial was designed. A number of 44 patients (60 wrists) with CTS were randomized to the DF group or the sham group. CSA and TCL thickness variables were registered by ultrasound. Clinical variables were assessed by the visual analogue scale and GROC scale. SPSS version 24.0 for MAC was used for statistical analysis. The group by time interaction between groups was analyzed using two-way repeated measures analysis of variance.

RESULTS

The DF group reduced CSA with a mean of 0.45 mm² (IC 95% 0.05 to 0.86) and TCL thickness with a mean reduction of 0.4 mm (IC 95% 0.6 to 2.1) compared to the sham group (p < 0.01, p < 0,03, respectively). Additionally, the DF group decreased the numbness intensity with a mean reduction of 3.47 (IC 95% 2.50 to 4.44, p < 0.01) and showed a statistically significant improvement on the GROC scale (p < 0.01).

CONCLUSIONS

DF treatment may significantly reduce CSA and TCL thickness, numbness intensity, and improved clinical perspective. DF applied in patients with mild to moderate CTS may prevent the progression of the disease as they age.

Sonographic Diagnosis of Carpal Tunnel Syndrome

Diagnostic ultrasound in the diagnosis of carpal tunnel syndrome is firmly established. Preoperative evaluation is based on quantitative parameters such as measurement of the pathologically enlarged cross-sectional area of the nerve. The value of postoperative ultrasound lies in the visualization of the anatomy and the conclusions that can be drawn from it. It focuses on the semiquantitative sonographic parameters of nerve compression. Nerve lesions and persistent strictures can be visualized and clearly localized. In recurrent disease, the primary focus is to dynamically exclude postoperative scarring, which results in a reduction of nerve gliding.

Neuromuscular Ultrasound: Indications in the Electrodiagnostic Laboratory

ABSTRACT

Accurate assessment of neuromuscular disorders is critical to facilitate timely treatment and achieve the best outcomes. Historically, electrodiagnostic studies have filled this role, but recently, neuromuscular ultrasound is being used in the electrodiagnostic laboratory. This review discusses the uses of neuromuscular ultrasound in the electrodiagnostic laboratory that have strong evidence, emphasizing those that could be adopted in a typical electrodiagnostic laboratory with a reasonable level of equipment and training. The evidence currently supports using neuromuscular ultrasound to diagnose carpal tunnel syndrome and ulnar neuropathies at the elbow and as a supplementary test when electrodiagnostic studies are suspected to be falsely negative or in axonal nonlocalizing lesions. Neuromuscular ultrasound can identify the causes of focal mononeuropathies, which can change treatment in specific cases. It is sensitive at identifying fasciculations and providing complementary evidence of autoimmune demyelinating polyneuropathies. It is particularly helpful in assessing nerves after trauma. Neuromuscular ultrasound is likely to prove even more useful in the electrodiagnostic laboratory as the technology continues to advance.

Automated Segmentation of Median Nerve in Dynamic Sonography Using Deep Learning: Evaluation of Model Performance

There is an emerging trend to employ dynamic sonography in the diagnosis of entrapment neuropathy, which exhibits aberrant spatiotemporal characteristics of the entrapped nerve when adjacent tissues move. However, the manual tracking of the entrapped nerve in consecutive images demands tons of human labors and impedes its popularity clinically. Here we evaluated the performance of automated median nerve segmentation in dynamic sonography using a variety of deep learning models pretrained with ImageNet, including DeepLabV3+, U-Net, FPN, and Mask-R-CNN. Dynamic ultrasound images of the median nerve at across wrist level were acquired from 52 subjects diagnosed as carpal tunnel syndrome when they moved their fingers. The videos of 16 subjects exhibiting diverse appearance and that of the remaining 36 subjects were used for model test and training, respectively. The centroid, circularity, perimeter, and cross section area of the median nerve in individual frame were automatically determined from the inferred nerve. The model performance was evaluated by the score of intersection over union (IoU) between the annotated and model-predicted data. We found that both DeepLabV3+ and Mask R-CNN predicted median nerve the best with averaged IOU scores close to 0.83, which indicates the feasibility of automated median nerve segmentation in dynamic sonography using deep learning.

Diagnosis Accuracy of Carpal Tunnel Syndrome in Diabetic Neuropathy

Background and objectives: Carpal tunnel syndrome (CTS) is a common pathology, but sometimes the diagnosis is delayed in patients with diabetic neuropathy (DN). The aim of the study is twofold: first, to compare the accuracy of ultrasound (US) with that of electroneurography (ENG) in the diagnosis of CTS associated with DN, using the clinical diagnosis as a reference standard, and second, to investigate the correlation between morphological US parameters and electrodiagnosis (EDX) measurements in patients with CTS and DN. Materials and Methods: This study included patients with DN. They were divided into two groups: Control (patients without CTS) and Cases (patients with CTS). We performed US and ENG in both hands, totaling 56 wrists, with 28 wrists in each group. Results: We found that the difference in the sensory distal latencies between the median and the ulnar nerves (ring finger) exhibited the highest diagnostic accuracy of all the US and ENG parameters, areas under the receiver operating characteristic (AUC) = 0.99 (95% CI 0.97–1), and it was significantly different from the best US diagnostic method. The wrist cross-sectional area (CSA) had the most accurate US diagnosis, while the wrist-to-forearm ratio had the worst AUC. Moreover, in the group of CTS and DN patients, the wrist CSA enlargement was statistically directly proportional to the median compound muscle action potential (CMAP) distal latency and inversely proportional to the antidromic median nerve conduction study (NCS) and the orthodromic median palm–wrist NCS. Conclusions: Both examinations can be used with confidence in the diagnosis of CTS overlapping with DN, but the EDX examination seems to be more accurate. Furthermore, we found a positive correlation between the US and EDX parameters.

Median nerve ultrasound in carpal tunnel syndrome with normal electrodiagnostic tests

INTRODUCTION

To evaluate the ultrasound findings of the median nerve in patients with clinical assigned carpal tunnel syndrome but normal nerve conduction studies.

METHODS

This prospective, cross-sectional study involved 41 patients (51 hands) with clinically assigned CTS and normal nerve conduction studies and 20 healthy controls (30 hands). Ultrasonography was performed in all participants, and cross-sectional area (CSA), hypoechogenicity, and mobility of the median nerve were evaluated. All patients were assessed with Boston Carpal Tunnel Questionnaire (BCTQ).

RESULTS

CSA of the median nerve in the wrist was significantly higher in the patient group when compared to the control group. Echogenicity and mobility were significantly decreased in the patient group. Ultrasound abnormalities were positively correlated with clinical features. A significant correlation was observed among sensory loss, provocative tests, body mass index, BCTQ, and high CSA.

CONCLUSION

US can help the clinicians with the diagnosis of carpal tunnel syndrome in patients with clinical symptoms but negative nerve conduction study results.

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.

Sensitivity of high-resolution ultrasonography in clinically diagnosed carpal tunnel syndrome patients with hand pain and normal nerve conduction studies

Background

Suspecting carpal tunnel syndrome (CTS) in patients with hand pain is usual. Considering the variable rate of false-negative results in nerve conduction study (NCS), as a frequent reference confirmatory standard test, we aimed to evaluate the diagnostic accuracy of neuromuscular ultrasound in patients with clinical evidence of CTS and normal NCS.

Methods

It was a diagnostic accuracy study conducted in the outpatient clinic of Rofaydeh Hospital, Tehran, Iran, between July 2012 and December 2016; it recruited clinically diagnosed CTS patients and a control group. All participants underwent comprehensive clinical examination, NCS, and high-resolution ultrasonography of the median nerve.

Results

Two hundred and fifty patients with clinical evidence of CTS met the inclusion criteria, of whom 103 (27.1%) had normal NCS and underwent an ultrasound examination. A cutoff point of 9.4 mm² (mean + 2 standard deviation) for median nerve cross-sectional area at the carpal tunnel inlet from the control group was set to detect 73% abnormality in the case group.

Conclusion

Ultrasonography had a sensitivity rate of 73% in patients with clinical CTS and negative NCS, increasing the overall diagnostic sensitivity for clinically suspected CTS in the electrodiagnostic lab setting to 92%. The study highlights the complementary role of ultraso-nography in diagnosing CTS in conjunction with NCS.

[Not Available]

Diagnosis of Carpal Tunnel Syndrome: Value of Ultrasound Compared to Nerve Conduction Studies Abstract. Carpal tunnel syndrome is the most common compression syndrome of the peripheral nerves. The patient's history with nocturnal brachialgia, daytime brachialgia, nocturnal paraesthesia and daytime paraesthesia (part of the 6-item CTS symptom scale) and a specific clinical exam take part while making a diagnosis. Additional diagnostics include electrophysiological testings. A high-resolution ultrasound examination for the evaluation of the morphology of the median nerve has gained importance in diagnosis of a carpal tunnel syndrome, whilst an electrophysiological exam allows a functional evaluation. Cardinal finding in ultrasound is an absolute or relative enlargement of the cross-section of the nerve at the edge proximal to the flexor retinaculum. Despite multiple studies that demonstrated ultrasound as a fist-line diagnostic tool, there is no consensus on optimal sonographic criteria for the definition of a compressed median nerve. Our aim was to demonstrate the use of ultrasound and electrophysiological exams for diagnostics of carpal tunnel syndrome in our own patient population and compared to the literature.

Neuromuscular ultrasound in patients with carpal tunnel syndrome and normal nerve conduction studies

INTRODUCTION

Nerve conduction studies (NCS) are sensitive for carpal tunnel syndrome (CTS), but a small proportion of patients with clinical CTS have normal NCS. This retrospective study was designed to assess the neuromuscular ultrasound findings in a group of CTS patients.

METHODS

The electronic medical record was reviewed by a neurologist to identify patients who had a diagnosis of CTS with normal NCS, including either mixed median-ulnar comparison or transcarpal sensory studies, and complete neuromuscular ultrasound evaluation for CTS.

RESULTS

Fourteen individuals (22 wrists) met all criteria. A total of 92.3% had median nerve cross-sectional area enlargement at the wrist (mean 16.3 mm² ), 100% had increased wrist-to-forearm median nerve area ratio (mean 2.4), 82.4% had decreased median nerve echogenicity, 75.0% had decreased median nerve mobility, and 7.1% had increased median nerve vascularity.

CONCLUSION

A large proportion of patients with clinical CTS but normal NCS have abnormal neuromuscular ultrasound findings. Muscle Nerve 55: 913-915, 2017.

Sonographic Visualization of Thenar Motor Branch of the Median Nerve: A Cadaveric Validation Study

BACKGROUND

The thenar motor branch (TMB) of the median nerve may be affected in carpal tunnel syndrome and can be injured during carpal tunnel surgery. Although ultrasound has been used to identify small nerves throughout the body, the sonographic evaluation of the TMB has not been investigated formally.

OBJECTIVE

To document the ability of ultrasound to visualize the TMB of the median nerve in an unembalmed cadaveric model.

DESIGN

Prospective laboratory investigation.

SETTING

Procedural skills laboratory at a tertiary medical center.

METHODS

On the basis of anatomical descriptions, dissection and clinical experience, a technique was developed to sonographically identify the presumed TMB of the median nerve at the distal carpal tunnel. A single, experienced examiner then identified the presumed TMB in 10 unembalmed, cadaveric upper limb specimens (4 right, 6 left) obtained from 9 donors (4 male, 5 female) ages 76-85 years with body mass indices of 18.2-29.5 kg/m² with both 12-3 MHZ and 16-7 MHz linear array transducers. The same examiner then injected 0.2-0.3 mL of diluted colored latex into and around the presumed TMB using direct ultrasound guidance. At a minimum of 24 hours postinjection, specimens were dissected under loupe magnification to determine the location of the latex injectate.

MAIN OUTCOME MEASURE

The location of latex injectate relative to the anatomically identified TMB.

RESULTS

A vertical, linear, hypoechogenic region was sonographically identified arising from the median nerve at the distal carpal tunnel in all 10 specimens and was hypothesized to represent the vertical segment of the TMB. Both transducers allowed identification of the TMB, although localization was subjectively facilitated by the higher frequency transducer. All 10 sonographically guided injections placed latex into and around the TMB of the median nerve, confirming that ultrasound had accurately identified the TMB.

CONCLUSIONS

Sonographic evaluation of the TMB of the median nerve is technically feasible and should be considered when clinically indicated. Further research and clinical experience is necessary to define the role of sonographic TMB imaging in the evaluation and management of patients with carpal tunnel syndrome.

LEVEL OF EVIDENCE

IV.

Electrosonodiagnosis in Carpal Tunnel Syndrome: A Proposed Diagnostic Algorithm Based on an Analytic Literature Review

BACKGROUND

Suspected carpal tunnel syndrome (CTS) remains the most common clinical scenario prompting referral for electrodiagnostic (EDx) studies to identify objective correlates of reported subjective symptoms and clinical examination findings. Despite much debate and a rapidly expanding literature, identification of an optimal algorithm for diagnosing focal median mononeuropathy at the wrist (FMMW) associated with CTS signs and symptoms remains elusive. The introduction and rapid dissemination of peripheral nerve ultrasound imaging (PN-USI) of the median nerve has raised new questions regarding the relative value of structural information from PN-USI versus physiological information from EDx in the diagnosis of FMMW, as well as the significance of various clinical signs and symptoms suggestive of CTS. The means by which PN-USI and EDx may be optimally deployed and integrated in the process of diagnosing FMMW remains to be clearly delineated.

OBJECTIVE

To complete an analytical literature review to guide the formulation of a clinical diagnostic algorithm (CDA) integrating the use of PN-USI and EDx for the optimal detection of FMMW in the context of making a clinical diagnosis of CTS.

DATA SOURCES

A structured literature review was performed on the MEDLINE medical literature database accessed through PubMed.

ANALYSIS

Papers with particular relevance and connection to the goal of formulating the CDA were selected from the identified studies. Studies specifically examining the correlations between systematically documented clinical symptomatology, EDx findings, and PN-USI findings were reviewed for consistent outcomes that could be incorporated into a CDA to guide the integration of these two complementary technologies in the diagnostic process.

LIMITATIONS

The formulation of the algorithm was limited to measures with established validity that can be readily obtained by means of widely accepted protocols using standard EDx and ultrasound equipment. The formulated algorithm assumes a consistent association between pathophysiology and anatomical deformation of the median nerve, which may not occur in certain situations. It may also not be as accurately applied to patients with CTS with significant comorbid neuromuscular conditions.

CONCLUSIONS

An algorithm has been developed and presented, and illustrated as a flow chart, based on findings reported in the relevant reviewed literature in which PN-USI is proposed as a painless and rapidly performed screening test for FMMW to be completed before subjecting a patient to a systematic EDx testing process.

Median nerve penetration by a persistent median artery and vein mimicking carpal tunnel syndrome

INTRODUCTION

Carpal tunnel syndrome (CTS) is a common clinical syndrome seen in the outpatient setting that is easily confirmed by electrodiagnostic testing.

METHODS

We describe the case of a patient who presented with the classic symptoms and neurological examination for CTS, but had a normal nerve conduction study and electromyogram.

RESULTS

Neuromuscular ultrasound of the median nerve on the symptomatic side revealed penetration of the nerve by a persistent median artery and vein in the mid-forearm, with a positive sonographic Tinel sign over this spot. This finding is an anatomical variation that has been described sparingly in the literature, mostly in cadavers. It has not been reported previously to be a mimic of CTS.

CONCLUSIONS

This case demonstrates the diagnostic utility of neuromuscular ultrasound and the importance of considering an anatomical variation involving the median nerve in the differential diagnosis of CTS.