Ultrasonography of peripheral nerves

Ultrasound accuracy for brachial plexus pathology

AIM

To determine (a) the accuracy of ultrasound in detecting brachial plexus pathology and (b) outline the advantages and limitations of ultrasound compared to MRI for imaging the brachial plexus.

MATERIAL AND METHODS

cases with clinically suspected brachial plexus pathology were evaluated first by ultrasound, followed by MRI. Patients with prior brachial plexus imaging were excluded. The final diagnosis was based on a combination of ultrasound, MRI, clinical follow-up, and surgical findings. The accuracy of the ultrasound was assessed by comparing the ultrasound and the final diagnoses. The mean clinical follow-up time following ultrasound was 1.8 ± 1.4 years.

RESULTS

Ninety-two (64%) of the 143 cases had normal brachial plexus ultrasound and MRI examinations. Fifty-one (36%) of 143 cases had brachial plexus pathology on MRI, comprising post-radiation fibrosis (n=25, 49%), nerve sheath tumor (n=11, 21%), traumatic injury (n=7, 14%), inflammatory polyneuropathy (n=4, 8%), malignant infiltration (n=2, 4%), desmoid fibromatosis (n=1,2%), and neuralgic amyotrophy (n=1, 2%). Overall diagnostic accuracy of ultrasound for brachial plexus pathology was 98% (140/143), with three discordant cases (neuralgic amyotrophy n=1, inflammatory neuropathy n=1, postradiation fibrosis n=1) regarded as normal on ultrasound assessment. Sensitivity, specificity, and positive and negative predictive value of ultrasound for identifying brachial plexus pathology were 94%, 100%, 100%, and 97%, respectively.

CONCLUSION

Ultrasound identifies brachial plexus pathology with high accuracy and specificity, showing comparable diagnostic efficacy to MRI. Ultrasound can serve as an effective first-line imaging investigation for suspected brachial plexus pathology.

Transformer-Based Automated Segmentation of the Median Nerve in Ultrasound Videos of Wrist-to-Elbow Region

Segmenting the median nerve is essential for identifying nerve entrapment syndromes, guiding surgical planning and interventions, and furthering understanding of nerve anatomy. This study aims to develop an automated tool that can assist clinicians in localizing and segmenting the median nerve from the wrist, mid-forearm, and elbow in ultrasound videos. This is the first fully automated single deep learning model for accurate segmentation of the median nerve from the wrist to the elbow in ultrasound videos, along with the computation of the cross-sectional area (CSA) of the nerve. The visual transformer architecture, which was originally proposed to detect and classify 41 classes in YouTube videos, was modified to predict the median nerve in every frame of ultrasound videos. This is achieved by modifying the bounding box sequence matching block of the visual transformer. The median nerve segmentation is a binary class prediction, and the entire bipartite matching sequence is eliminated, enabling a direct comparison of the prediction with expert annotation in a frame-by-frame fashion. Model training, validation, and testing were performed on a dataset comprising ultrasound videos collected from 100 subjects, which were partitioned into 80, ten, and ten subjects, respectively. The proposed model was compared with U-Net, U-Net++, Siam U-Net, Attention U-Net, LSTM U-Net, and Trans U-Net. The proposed transformer-based model effectively leveraged the temporal and spatial information present in ultrasound video frames and efficiently segmented the median nerve with an average dice similarity coefficient (DSC) of approximately 94% at the wrist and 84% in the entire forearm region.

Ultrasound morphometry of the cervical vagus nerve for daily clinical practice: Reference values for cross sectional area and fascicle count

INTRODUCTION

High resolution ultrasound (US) of the cervical vagus nerve (CVN) is clinically relevant in the diagnostic workup and during neurostimulation therapy of several neurologic diseases. This prospective study aims to provide reference data of the cross-sectional area (CSA) and fascicle count of the normal CVN and to investigate their possible association with anthropometric data in a large cohort of patients.

METHODS

A total of 657 CVNs in 330 individuals without history of neurological disease were examined using US (7-15Mhz). The CVN fascicle count and CSA inside the hyperechoic epineurium at the level of the thyroid lobes were measured. Three CSA measurements were performed to calculate the mean value. Anthropometric data were recorded.

RESULTS

The mean fascicle count was 2.4 ± 1.1 (right) and 2 ± 1 (left) (paired t- test, p < 0.001). Two CVN patterns were identified: A single hypoechoic fascicular structure (26.2 % right, 36.3 % left) and a honeycomb structure of 2-6 discrete fascicles (72.3 % right, 63.7 % left). Right CVN mean CSA was larger compared to left (2.3 ± 1 mm2 and 1.8 ± 0.8 mm2 respectively, t-test, p-0.000). There was no difference in the CSA values between sex and no correlation to age or height. A positive correlation between the CSA and weight and BMI was found (Pearson's correlation, p = 0.01 right and p = 0.05 left).

CONCLUSION

The right CVN has larger CSA and contains more fascicles than the left. CVN is usually mono- or oligo-fascicular with a honeycomb appearance. The CSA increased with increasing BMI but no age and sex specific differences were noted.

A pilot prospective cohort study using experimental quantification of early peripheral nerve regeneration with high-frequency three-dimensional tomographic ultrasound (HFtUS)

Quantification of peripheral nerve regeneration after injury relies upon subjective outcome measures or electrophysiology assessments requiring fully regenerated neurons. Nerve surgeons and researchers lack objective, quantifiable information on the site of surgical repair and regenerative front. To address this need, we developed a quantifiable, visual, clinically available measure of early peripheral nerve regeneration using high-frequency, three-dimensional, tomographic ultrasound (HFtUS). We conducted a prospective, longitudinal study of adult patients with ulnar and/or median nerve injury of the arm undergoing direct epineurial repair within 5 days of injury. Assessment of morphology, volumetric and 3D grey-scale quantification of cross-sectional views were made at baseline up to 15 months post-surgery. Sensory and motor clinical outcome measures and patient reported outcome measures (PROMs) were recorded. Five participants were recruited to the study. Our data demonstrated grey-scale values (an indication of axonal density) increased in distal stumps within 2-4 months after repair, returning to normal as regeneration completed (4-6 months) with concomitant reduction in intraneural volume as surgical oedema resolved. Two patients with abnormal regeneration were characterized by increased intraneural volume and minimal grey-scale change. HFtUS may quantify early peripheral nerve regeneration offering a window of opportunity for surgical intervention where early abnormal regeneration is detected.

Application of ultrasound images-based radiomics in carpal tunnel syndrome: Without measuring the median nerve cross-sectional area

PURPOSE

By constructing a prediction model of carpal tunnel syndrome (CTS) based on ultrasound images, it can automatically and accurately diagnose CTS without measuring the median nerve cross-sectional area (CSA).

METHODS

A total of 268 wrists ultrasound images of 101 patients diagnosed with CTS and 76 controls in Ningbo NO.2 Hospital from December 2021 to August 2022 were retrospectively analyzed. The radiomics method was used to construct the Logistic model through the steps of feature extraction, feature screening, reduction, and modeling. The area under the receiver operating characteristic curve was calculated to evaluate the performance of the model, and the diagnostic efficiency of the radiomics model was compared with two radiologists with different experience.

RESULTS

The 134 wrists in the CTS group included 65 mild CTS, 42 moderate CTS, and 17 severe CTS. In the CTS group, 28 wrists median nerve CSA were less than the cut-off value, 17 wrists were missed by Dr. A, 26 wrists by Dr. B, and only 6 wrists were missed by radiomics model. A total of 335 radiomics features were extracted from each MN, of which 10 features were significantly different between compressed and normal nerves, and were used to construct the model. The area under curve (AUC) value, sensitivity, specificity, and accuracy of the radiomics model in the training set and testing set were 0.939, 86.17%, 87.10%, 86.63%, and 0.891, 87.50%, 80.49%, and 83.95%, respectively. The AUC value, sensitivity, specificity, and accuracy of the two doctors in the diagnosis of CTS were 0.746, 75.37%, 73.88%, 74.63% and 0.679, 68.66%, 67.16%, and 67.91%, respectively. The radiomics model was superior to the two-radiologist diagnosis, especially when there was no significant change in CSA.

CONCLUSION

Radiomics based on ultrasound images can quantitatively analyze the subtle changes in the median nerve, and can automatically and accurately diagnose CTS without measuring CSA, especially when there was no significant change in CSA, which was better than radiologists.

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.

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.

Quantitative Ultrasound Techniques Used for Peripheral Nerve Assessment

AIM

This review article describes quantitative ultrasound (QUS) techniques and summarizes their strengths and limitations when applied to peripheral nerves.

METHODS

A systematic review was conducted on publications after 1990 in Google Scholar, Scopus, and PubMed databases. The search terms "peripheral nerve", "quantitative ultrasound", and "elastography ultrasound" were used to identify studies related to this investigation.

RESULTS

Based on this literature review, QUS investigations performed on peripheral nerves can be categorized into three main groups: (1) B-mode echogenicity measurements, which are affected by a variety of post-processing algorithms applied during image formation and in subsequent B-mode images; (2) ultrasound (US) elastography, which examines tissue stiffness or elasticity through modalities such as strain ultrasonography or shear wave elastography (SWE). With strain ultrasonography, induced tissue strain, caused by internal or external compression stimuli that distort the tissue, is measured by tracking detectable speckles in the B-mode images. In SWE, the propagation speed of shear waves, generated by externally applied mechanical vibrations or internal US "push pulse" stimuli, is measured to estimate tissue elasticity; (3) the characterization of raw backscattered ultrasound radiofrequency (RF) signals, which provide fundamental ultrasonic tissue parameters, such as the acoustic attenuation and backscattered coefficients, that reflect tissue composition and microstructural properties.

CONCLUSIONS

QUS techniques allow the objective evaluation of peripheral nerves and reduce operator- or system-associated biases that can influence qualitative B-mode imaging. The application of QUS techniques to peripheral nerves, including their strengths and limitations, were described and discussed in this review to enhance clinical translation.

Contrast-enhanced ultrasonography for evaluation of the blood perfusion of sciatic nerves in healthy dogs

Blood supply to the peripheral nerves is essential for fulfilling their structural and functional requirements. This prospective, experimental, exploratory study aimed to assess the feasibility of contrast-enhanced ultrasonography (CEUS) for evaluating blood perfusion of the sciatic nerve in normal dogs. Contrast-enhanced ultrasonography examinations were performed on the bilateral sciatic nerves after bolus injection of Sonazoid™ (0.015 mL/kg) in 12 healthy Beagles for 150 s. Then, qualitative assessment of the wash-in timing, degree and enhancement patterns, and quantitative measurement of the peak intensity and time to peak intensity were performed from the sciatic nerve. The results were compared to those obtained from the adductor muscle around the nerve and caudal gluteal artery. After contrast agent injection, the sciatic nerve was enhanced at approximately 13-14 s, immediately after wash-in of the caudal gluteal artery. The peak intensity of the sciatic nerve was significantly lower than that of the caudal gluteal artery and higher than that of the adductor muscle. The time to peak intensity was significantly slower than that of the caudal gluteal artery; but was not significantly different from that of the adductor muscle. There were no significant differences in the peak intensity and time to peak intensity between the left and right sciatic nerves. These results demonstrate the feasibility of CEUS to assess blood perfusion of the sciatic nerve in healthy dogs qualitatively and quantitatively. This result from healthy dogs could serve as a reference for further studies that evaluate the sciatic nerve under pathological conditions.

Ultrasound-based radiomics in the diagnosis of carpal tunnel syndrome: The influence of regions of interest delineation method on mode

BACKGROUND

In the recent years, artificial intelligence (AI) algorithms have been used to accurately diagnose musculoskeletal diseases. However, it is not known whether the particular regions of interest (ROI) delineation method would affect the performance of the AI algorithm.

PURPOSE

The purpose of this study was to investigate the influence of ROI delineation methods on model performance and observer consistency.

METHODS

In this retrospective analysis, ultrasound (US) measures of median nerves affected with carpal tunnel syndrome (CTS) were compared to median nerves in a control group without CTS. Two methods were used for delineation of the ROI: (1) the ROI along the hyperechoic medial edge of the median nerve but not including the epineurium (MN) (ROI1); and (2) the ROI including the hyperechoic epineurium (ROI2), respectively. The intra group correlation coefficient (ICC) was used to compare the observer consistency of ROI features (i.e. the corresponding radiomics parameters). Parameters α₁ and α₂ were obtained based on the ICC of ROI₁ features and ROI₂ features. The ROC analysis was used to determine the area under the curve (AUC) and evaluate the performance of the radiologists and network. In addition, four indices, namely sensitivity, specificity, positive prediction and negative prediction were analyzed too.

RESULTS

A total of 136 wrists of 77 CTS group and 136 wrists of 74 control group were included in the study. Control group was matched to CTS group according to the age and sex. The observer consistency of ROI features delineated by the two schemes was different, and the consistency of ROI₁ features was higher (α1 ˃ α2). The intra-observer consistency was higher than the inter-observer consistency regardless of the scheme, and the intra-observer consistency was higher when chose scheme one. The performances of models based on the two ROI features were different, although the AUC of each model was greater than 0.8.The model performed better when the MN epineurium was included in the ROI. Among five artificial intelligence algorithms, the Forest models (model₁ achieved an AUC of 0.921 in training datasets and 0.830 in testing datasets; model₂ achieved an AUC of 0.967 in training datasets and 0.872 in testing datasets.) obtained the highest performance, followed by the support vector machine (SVM) models and the Logistic models. The performances of the models were significantly better than the inexperienced radiologist (Dr. B. Z. achieved an AUC of 0.702).

CONCLUSION

Different ROI delineation methods may affect the performance of the model and the consistency of observers. Model performance was better when the ROI contained the MN epineurium, and observer consistency was higher when the ROI was delineated along the hyperechoic medial border of the MN.

Value of ultrasound assessment for traumatic nerve injury of the upper limb

Aim of work

The type of traumatic peripheral nerve injury is a key factor for determining optimal treatment. Proper assessment of peripheral nerve injury facilitates appropriate treatment, significantly affects prognosis, and reduces disabilities. This study evaluated ultrasonography (US) to assess upper limb traumatic nerve injuries and compared the US with electrodiagnostic studies as the gold standard.

Materials and Methods

Participants were 69 adults (57 [83%] men, 12 [17%] women; mean age 36.3 ± 13.5 years) with a total of 96 peripheral nerve injuries (duration of 1 month–3 years). High-frequency US examinations and electro-physiologic studies confirmed upper limb peripheral nerve injury.

Results

Nerve discontinuation was diagnosed in 15 (15.6%) nerves; the cross-sectional area was increased in 33 (34.4%) nerves. Of 96 injuries, 54 (56.3%) were median, 24 (25%) were ulnar, and 18 (18.8%) were radial nerves. No statistically significant difference was found between US and electro-physiologic studies for nerve injury diagnosis (p = 0.054).

Conclusion

No significant differences were found between US and electro-physiologic studies for diagnosis of nerve injuries; however, US was valuable to assess surrounding tissue and supplied muscles. The capabilities to detect nerve injury and associated distal muscular, vascular, and other regional structures position the US as a complementary diagnostic tool.

Diagnostic value of shear wave ultrasound elastography of tibial nerve in patients with diabetic peripheral neuropathy

Background

Diabetic peripheral neuropathy (DPN) is a major complication of Diabetes mellitus. So this study aimed at investigation of the value of tibial nerve stiffness measured by shear wave ultrasound elastography (SWE) for detection of DPN. This case–control study involved 50 patients with DPN, 50 patients with diabetes mellitus but without DPN, and 50 healthy controls. Clinical examination, nerve conduction study of both tibial nerves, high resolution ultrasound and SWE to assess cross sectional area "CSA" of tibial nerves, and tibial nerves mean stiffness, respectively. ROC curve analysis was also performed.

Results

Mean tibial nerve stiffness by SWE was higher in patients with DPN compared to other groups (P value < 0.001). The CSA of the tibial nerve in the DPN group was significantly larger than that in the other groups (P value = 0.01). The cutoff value by ROC curve analysis for tibial nerve stiffness to differentiate patients with DPN and control group was 70.6 kPa (P value < 0.001, 95.4% sensitivity, 94.7% specificity, AUC = 0.963), while 86.5 kPa was the optimal cutoff point to differentiate patients with DPN and other groups with a 94.6% sensitivity, 93.8% specificity, AUC of 0.975 and P value < 0.001. Higher diagnostic accuracy was found when combination of SWE and high resolution US (high resolution US + shear wave; 0.987, P value < 0.001).

Conclusions

Tibial nerve stiffness was increased in patients with DPN. SWE can be used as an effective complementary method in diagnosis of DPN with high sensitivity and accuracy.

Clinical Application of Ultra-High-Frequency Ultrasound

Musculoskeletal ultrasound involves the study of many superficial targets, especially in the hands, wrists, and feet. Many of these areas are within the first 3 cm of the skin surface and are ideal targets for ultra-high-frequency ultrasound. The high spatial resolution and the superb image quality achievable allow foreseeing a wider use of this novel technique, which has the potential to bring innovation to diagnostic imaging.

Assessment of Motor Function in Peripheral Nerve Injury and Recovery

Introduction

Peripheral nerve injuries can be difficult to diagnose, treat, and monitor given their highly variable presentation. When the status of nerves is not accurately assessed, treatment may be delayed or overlooked and can result in lasting functional deficits. As our understanding of nerve repair and generation evolves, so will tools for evaluating both the functional and morphological status of peripheral nerves.

Objective

There is currently no single article which provides a detailed, comprehensive view of the literature comparing the clinical utility of various assessment modalities. Furthermore, there is no consensus on the optimal assessment algorithm for peripheral nerve injuries.

Methods

We performed a literature review using a comprehensive combination of keywords and search algorithm. The search was focused on clinical data regarding the assessment of peripheral nerves Results: This review may help to determine the appropriate tools that are currently available for monitoring nerve function both pre and postoperatively. Additionally, the review demonstrates possible roles and areas of improvement for each tool used to assess motor function.

Conclusion

As surgeons work to improve treatments for peripheral nerve injury and dysfunction, identifying the most appropriate existing measures of success and future directions for improved algorithms could lead to improved patient outcomes.

Point-of-care ultrasound of peripheral nerves in the diagnosis of Hansen's disease neuropathy

Introduction

Hansen's disease (HD) is the most common cause of treatable peripheral neuropathy in the world that may or may not involve skin manifestations, and physical examination based on simplified neurologic evaluation is a subjective and inaccurate procedure. High-resolution ultrasound (HRUS) can be used to evaluate peripheral nerves and is a validated technique of good reproducibility, permitting a detailed and precise examination.

Objectives

We proposed to establish objective criteria for absolute values of the measurement of the CSA of peripheral nerves and their indices of the ΔCSA and ΔTpT in the diagnosis of Hansen's disease neuropathy as compared with healthy voluntaries.

Materials and methods

In municipalities from different regions of Brazil, we randomly selected 234 volunteer Brazilian patients diagnosed with leprosy to be submitted to peripheral nerve echography and compared with 49 healthy Brazilian volunteers.

Results

Hansen Disease assessed by high resolution ultrasound is a primarily neural disease that leads to multiple hypertrophic mononeuropathy characterized by CSA values exceeding normal limits (Med CT = 10.2 mm²; UT = 9.8 mm²; UPT = 9.3 mm²; CFFH = 18.3 mm²; T = 9.6 mm²), and the pattern of asymmetry (ΔCSA>2.5 mm² with RR 13) and focality (ΔTPT > 2.5 mm² with RR 6.4) of this thickening has higher sensitivity (76,1%) and specificity (87,8 %) for its early diagnosis that laboratory tests. Analyzing each subject, the percentage of thickened nerves detected among the total number of nerves assessed was higher among patients with HD than among healthy individuals (p < 0.0001). Individuals with two or more thickened nerves were at 24.1 times higher relative risk (95% CI: 6.74–88.98) of HD.

Reference Values for the Cross Sectional Area of Normal Tibial Nerve on High-resolution Ultrasonography

AIM

The aim of the study was to establish reference values for the cross-sectional area of the tibial nerve on high-resolution ultrasonography and to investigate the relationship between the cross-sectional area of the tibial nerve and subject's age, gender, height (in cm), weight (in kg) and body mass index.

METHODS

Two hundred subjects of either gender and over 18 years of age with no history of peripheral neuropathy or trauma to the lower limb were evaluated with high-resolution ultrasonography. Mean cross-sectional areas of tibial nerves were measured at two different levels in both lower limbs, first at 1 cm below the bifurcation of the sciatic nerve into tibial and common peroneal nerves (level I) and the second at 1 cm superior and posterior to the medial malleolus (level II).

RESULTS

The mean cross-sectional area measured at level I (0.196 + 0.014 cm²) was larger than the one measured at level II (0.111 ± 0.011 cm²). A positive correlation was found between the mean cross-sectional area and height, weight, and body mass index (p <0.05). Women had smaller cross-sectional areas of the tibial nerves than men at both sites. In addition, no significant relationship was found with the age of the subjects (p >0.05).

CONCLUSION

The established reference values of the cross-sectional area of the tibial nerve will aid in early diagnosis of peripheral neuropathy.

MallesNet: A multi-object assistance based network for brachial plexus segmentation in ultrasound images

Ultrasound-guided injection is widely used to help anesthesiologists perform anesthesia in peripheral nerve blockade (PNB). However, it is a daunting task to accurately identify nerve structure in ultrasound images even for the experienced anesthesiologists. In this paper, a Multi-object assistance based Brachial Plexus Segmentation Network, named MallesNet, is proposed to improve the nerve segmentation performance in ultrasound image with the assistance of simultaneously segmenting its surrounding anatomical structures (e.g., muscle, vein, and artery). The MallesNet is designed by following the framework of Mask R-CNN to implement the multi object identification and segmentation. Moreover, a spatial local contrast feature (SLCF) extraction module is proposed to compute contrast features at different scales to effectively obtain useful features for small objects. And the self-attention gate (SAG) is also utilized to capture the spatial relationships in different channels and further re-weight the channels in feature maps by following the design of non-local operation and channel attention. Furthermore, the upsampling mechanism in original Feature Pyramid Network (FPN) is improved by adopting the transpose convolution and skip concatenation to fine-tune the feature maps. The Ultrasound Brachial Plexus Dataset (UBPD) is also proposed to support the research on brachial plexus segmentation, which consists of 1055 ultrasound images with four objects (i.e., nerve, artery, vein and muscle) and their corresponding label masks. Extensive experimental results using UBPD dataset demonstrate that MallesNet can achieve a better segmentation performance on nerves structure and also on surrounding structures in comparison to other competing approaches.

Ultrasonographic Evaluation of Peripheral Nerves: Technical Considerations

Advances in ultrasonographic (US) technology featuring high-resolution transducers have revolutionized US over recent years as a modality increasingly used in the evaluation of musculoskeletal structures and peripheral nerves. A wide variety of nerve pathologies can be detected, such as neoplastic and tumorlike lesions, entrapment syndromes, posttraumatic injuries, and inflammatory conditions. US can serve as an imaging tool for guiding percutaneous treatments, such as injection therapies or hydrodissection, and assist with perioperative nerve marking and visualization of peripheral nerves in the operating room. This article describes the normal US appearance of peripheral nerves, US imaging techniques, common peripheral nerve pathologies, and interventional applications.

Ultrasound-guided peripheral intravenous cannulation for patients requiring dental surgery under intravenous dental sedation

Dental surgeons regularly provide intravenous dental sedation and oral/transmucosal sedation, which involves cannulation. Cannulation is an essential skill that dental surgeons should be competent to perform, but certain patient groups may be difficult to cannulate. Ultrasound-guided peripheral intravenous cannulation is an evidence-based technique already used in radiology, emergency medicine, and anaesthesia. Ultrasound-guided peripheral intravenous cannulation has been shown to reduce complications and significantly increase the success of cannulation in patients with difficult intravenous access (DIVA); it may also be preferable in certain special care patient groups. The application of ultrasound-guided peripheral intravenous cannulation should be considered for patients with DIVA who require intravenous dental sedation or other common procedures in dental surgery that involve cannulation.

Discusses the potential future changes to the provision of dental sedation.

Discusses possible indications and contraindications of USG-PIVC for intravenous dental sedation.

Describes the method of USG-PIVC and current barriers to implementing USG-PIVC for intravenous dental sedation.

Ultrasound reference values for peripheral nerve cross-sectional areas and indices in a sample of healthy individuals in Brazil

Objective

To establish peripheral nerve cross-sectional area (CSA) reference values (absolute values, measures of asymmetry, and measures of focality) for healthy individuals in Brazil.

Materials and Methods

Sixty-six healthy volunteers underwent high-resolution ultrasound of the peripheral nerves. We obtained CSA measurements for three peripheral nerves, at specific locations: the median nerve, in the carpal tunnel (MT); the ulnar nerve, at the cubital tunnel site (UT) and at the pre-tunnel site (UPT); and the common fibular nerve, near the fibular head (FH). We calculated the CSA indices between the same sites on different sides (ΔCSAs) and between the ulnar nerve tunnel and pre-tunnel sites on the same side (ΔTPT).

Results

A total of 132 neural sites were analyzed, and the following CSA values (mean ± SD, median) were obtained: MT (6.3 ± 1.9 mm², 6.0 mm²); UT (6.2 ± 1.6 mm², 6.1 mm²); UPT (5.6 ± 1.7 mm², 5.4 mm²); and FH (10.0 ± 3.7 mm², 9.9 mm²). The ΔCSA values (mean ± SD, median) were as follows: MT (0.85 ± 0.7 mm², 0.95); UT (0.81 ± 0.62 mm², 0.95); UPT (0.61 ± 0.51 mm², 0.5); and FH (1.0 ± 0.77 mm², 1.0). The ΔTPT (mean ± SD, median) was (1.0 ± 0.8 mm², 1.0).

Conclusion

Among individuals in Brazil, peripheral nerve CSA values tend to be higher among males and to increase with aging. However, the same does not appear to hold true for the ΔCSA or the ΔTPT, the exception being the difference between the right and left UT. Differences in CSA values greater than 2.5 mm² between sides or between sites along the same nerve can indicate asymmetry or focal thickening in neuropathy, respectively.

Anatomy of the nerves, vessels, and muscular compartments of the forearm, as revealed by high-resolution ultrasound. Part 1: overall structure and forearm compartments

In recent decades, high-resolution ultrasound (HRUS) has revolutionized the morphological and structural evaluation of peripheral nerves and muscles, revealing details of the internal structure of the neural fascicles and muscle architecture. Applications range from diagnostics to interventional procedures. The anatomy of the forearm region is complex, with several muscles and an extensive network of vessels and nerves. To guarantee the success of the evaluation by HRUS, knowledge of the normal anatomy of the region is essential. The aim of these two companion articles is to present the normal anatomy of the nerves and compartments of the forearm, as revealed by HRUS, as well as the relationships between the main vessels and nerves of the region. Part 1 aims to review the overall structure of nerves, muscles and tendons, as seen on HRUS, and that of the forearm compartments. We present a practical approach, with general guidelines and tips on how best to perform the study. Part 2 is a pictorial essay about compartment vascularization and cutaneous innervation. Knowledge of the normal anatomy of the forearm improves the technical quality of the examinations, contributing to better diagnoses, as well as improving the performance and safety of interventional procedures.

Can Anti-embolism Stockings Cause Common Peroneal Nerve Palsy Following Total Hip Arthroplasty Via Anterior Approach? A Case Report

We present a patient who had a common peroneal nerve palsy complication due to anti-embolism stocking compression following total hip arthroplasty (THA) surgery performed via the anterior approach (AA). The patient was a 17-year-old underweight female and have experienced bilateral hip pain for the last 3 years. Pelvic X-rays revealed bilateral osteonecrosis of the femoral head and THA surgery for the left hip via the AA was done. Common peroneal palsy developed due to anti-embolism stocking compression on the first postoperative day, which was confirmed by ultrasonography (USG). The common peroneal nerve returned to full function in the third postoperative month with complete healing and the patient was followed up for 3 years. Several etiologic factors have been reported as the cause of the common peroneal nerve palsy following THA surgery. Common peroneal palsy caused by anti-embolism stocking as in our case is an etiologic factor to be considered by arthroplasty surgeons.

Can the axial cross-sectional area of the tibial nerve be used to diagnose tarsal tunnel syndrome? An ultrasonography study

INTRODUCTION

The axial cross-sectional area (CSA) of the tibial nerve can be measured with ultrasonography. In patients who have posteromedial tarsal tunnel syndrome (TTS), there is little information on the nerve's CSA even though this information could be useful for determining whether the nerve is damaged. This led us to carry out a case-control study in which the tibial nerve's axial CSA was measured in healthy patients and in patients with TTS.

HYPOTHESIS

The tibial nerve's axial CSA can be used as a diagnostic criterion for TTS.

METHODS

Twenty-three patients (27 feet) (11 men, 12 women, mean age=54±14 years), who had clinical and electroneuromyography signs of TTS, were compared to 21 healthy adults (8 men, 13 women, mean age 39±10 years). An ultrasonography examination was carried out to look for a source of nerve compression, then the axial CSA of the tibial nerve was measured 10cm above the tarsal tunnel (_lCSA) and inside the tunnel itself (_ttCSA). The difference between the two measurements was then calculated: _ΔCSA=_ttCSA-_lCSA. The data were analysed using correlation tests and non-parametric tests, a multivariate linear regression and ROC tests.

RESULTS

A compressive cause was found by ultrasonography in 13 patients. The mean values of _ttCSA and _ΔCSA were 20.1±8.8 mm² [6-42] vs. 10.3±2.3 mm² [8-14] (p=0.0001) and 9.8±6.7 mm² [0-29] vs. -0.2±1.8 mm² [-3-4] (p<0.0001) in the patients and the controls, respectively. The differences in _ΔCSA remained significant in the multivariate analysis after adjusting for age and weight. The best threshold for _ttCSA in the TTS group was 15 mm² with 74% sensitivity and 100% specificity. The best threshold for _ΔCSA was 5mm² with 81% sensitivity and 100% specificity.

DISCUSSION

The difference in the measured axial CSA of the tibial nerve by ultrasonography between the posteromedial tarsal tunnel and 10cm above the tunnel is a key data point for the diagnosis of tarsal tunnel syndrome with and without compressive etiology.

LEVEL OF EVIDENCE

III, diagnostic case-control study.

Cubital tunnel syndrome

Cubital tunnel syndrome (CuTS) is the second most common compression neuropathy of the upper limb, presenting with disturbance of ulnar nerve sensory and motor function.The ulnar nerve may be dynamically compressed during movement, statically compressed due to reduction in tunnel volume or compliance, and tension forces may cause ischaemia or render the nerve susceptible to subluxation, further causing local swelling, compression inflammation and fibrosis.Superiority of one surgical technique for the management of CuTS has not been demonstrated. Different techniques are selected for different clinical situations with simple decompression being the most common procedure due to its efficacy and low complication rate.Adjunctive distal nerve transfer for denervated muscles using an expendable motor nerve to restore the axon population in the distal nerve is in its infancy but may provide a solution for severe intrinsic weakness or paralysis. Cite this article: EFORT Open Rev 2021;6:743-750. DOI: 10.1302/2058-5241.6.200129.

Comparison of High Resolution Ultrasonography with Clinical Examination in the Assessment of Peripheral Nerve Involvement in Leprosy

Context:

Assessment of peripheral nerves in leprosy by clinical methods is subject to considerable inter-observer variability. High resolution ultrasonography (HRUS) can assess peripheral nerves more objectively.

Aims:

To compare the findings of peripheral nerve involvement in newly diagnosed cases of leprosy by clinical and sonological methods.

Settings and Design:

Cross sectional study in a tertiary care teaching hospital.

Subjects and Methods:

Four pairs of peripheral nerves of 40 newly diagnosed patients with leprosy were examined clinically and by HRUS.

Statistical Analysis Used:

Agreement between clinical examination and HRUS using kappa statistic; sensitivity; specificity; and predictive values.

Results:

Of the 320 nerves examined, 71 (22.18%) were abnormal clinically and 63 (19.7%) sonologically. Sonological abnormalities were increased cross sectional area (n = 63; 100%), hypoechogenicity with loss of fascicular architecture (n = 46; 73%) and increased vascularity (n = 35; 55.6%). There was moderate agreement (Cohen's Ḳ = 0.59) between clinical and sonological findings. HRUS findings were abnormal in 18 (7.2%) nerves that were clinically normal. HRUS was normal in 26 (36.6%) nerves which were clinically abnormal. Sensitivity of HRUS compared to clinical examination was 63%; specificity 92.7%; positive predictive value 71.4%; and negative predictive value 89.9%. Increased cross sectional area agreed with clinical findings the most.

Conclusions:

HRUS has low sensitivity (63%) and high specificity (92.7%) to identify abnormal peripheral nerves in leprosy, compared to clinical examination. It could detect abnormality of some (n = 18, 7.2%) clinically normal nerves, but showed normal findings of some nerves (n = 26, 36.6%), which were considered clinically abnormal.

Reference values for the cross-sectional area of the normal sciatic nerve using high-resolution ultrasonography

Aim

High-resolution ultrasonography is a new and promising technique to evaluate peripheral and spinal nerves. Its validity as a diagnostic tool in neurological diseases has been demonstrated in adults. The aims of study were to establish the reference values for the cross-sectional area of the normal sciatic nerve on high-resolution ultrasonography, and to determine the relationship between the cross-sectional area of the normal sciatic nerve and the subjects' age, gender, height (in cm), weight (in kg), and body mass index.

Material and methods

Two hundred subjects of both genders and above 18 years of age were studied with high-resolution ultrasonography. The subjects had no history of peripheral neuropathy or trauma to the lower limb. The cross-sectional areas of the normal sciatic nerves were obtained at two different levels in both lower limbs. The mean cross-sectional areas of the sciatic nerves were measured at two different levels, one located at 1 cm above the bifurcation of the sciatic nerve into the tibial and common peroneal nerves, and the other 4 cm above the bifurcation of the sciatic nerve into the tibial and common peroneal nerves.

Results

A positive correlation of the mean cross-sectional area was established with height, weight, and body mass index. Women had smaller cross-sectional areas of the normal sciatic nerves than men at both measuring sites. No significant relationship was established with the age of the subjects.

Conclusions

The established reference values of the cross-sectional area of the sciatic nerve can facilitate the analysis of pathological nerve conditions.

Initial findings in traumatic peripheral nerve injury and repair with diffusion tensor imaging

OBJECTIVE

Management of peripheral nerve injuries requires physicians to rely on qualitative measures from patient history, electromyography, and physical exam. Determining a successful nerve repair can take months to years for proximal injuries, and the resulting delays in clinical decision-making can lead to a negative impact on patient outcomes. Early identification of a failed nerve repair could prevent permanent muscle atrophy and loss of function. This study aims to test the feasibility of performing diffusion tensor imaging (DTI) to evaluate injury and recovery following repair of wrist trauma. We hypothesize that DTI provides a noninvasive and reliable assessment of regeneration, which may improve clinical decision-making and alter the clinical course of surgical interventions.

METHODS

Clinical and MRI measurements from subjects with traumatic peripheral nerve injury, carpal tunnel syndrome, and healthy control subjects were compared to evaluate the relationship between DTI metrics and injury severity.

RESULTS

Fractional anisotropy from DTI was sensitive to differences between damaged and healthy nerves, damaged and compressed nerves, and injured and healthy contralateral nerves. Longitudinal measurements in two injury subjects also related to clinical outcomes. Implications of other diffusion measures are also discussed.

INTERPRETATION

DTI is a sensitive tool for wrist nerve injuries and can be utilized for monitoring nerve recovery. Across three subjects with nerve injuries, this study has shown how DTI can detect abnormalities between injured and healthy nerves, measure recovery, and determine if re-operation was successful. Additional comparisons to carpal tunnel syndrome and healthy nerves show that DTI is sensitive to the degree of impairment.

Use of Reflective Tape to Detect Ultrasound Transducer Movement: A Validation Study

During dynamic ultrasound assessments, unintended transducer movement over the skin needs to be prevented as it may bias the results. The present study investigated the validity of two methods quantifying transducer motion. An ultrasound transducer was moved on a pre-specified 3 cm distance over the semitendinosus muscle of eleven adults (35.8 ± 9.8 years), stopping briefly at intervals of 0.5 cm. Transducer motion was quantified (1) measuring the 2-D displacement of the shadow produced by reflective tape (RT) attached to the skin and (2) using a marker-based, three-dimensional movement analysis system (MAS). Differences between methods were detected with Wilcoxon tests; associations were checked by means of intraclass correlation coefficients (ICC 3.1) and Bland–Altman plots. Values for RT (r = 0.57, p < 0.001) and MAS (r = 0.19, p = 0.002) were significantly higher than true distances (TD). Strong correlations were found between RT and TD (ICC: 0.98, p < 0.001), MAS and TD (ICC: 0.95, p < 0.001), and MAS and RT (ICC: 0.97, p < 0.001). Bland–Altman plots showed narrow limits of agreement for both RT (−0.49 to 0.13 cm) and MAS (−0.49 to 0.34 cm) versus TD. RT and MAS are valid methods to quantify US transducer movement. In view of its low costs and complexity, RT can particularly be recommended for application in research and clinical practice.

Accurate automated diagnosis of carpal tunnel syndrome using radiomics features with ultrasound images: A comparison with radiologists' assessment

PURPOSE

Ultrasonography is the most common imaging modality used to diagnose carpal tunnel syndrome (CTS). Recently artificial intelligence algorithms have been used to diagnose musculoskeletal diseases accurately without human errors using medical images. In this work, a computer-aided diagnosis (CAD) system is developed using radiomics features extracted from median nerves (MN) to diagnose CTS accurately.

METHOD

This study is performed on 228 wrists from 65 patients and 57 controls, with an equal number of control and CTS wrists. Nerve conduction study (NCS) is considered as the gold standard in this study. Two radiologists used two guides to evaluate and categorize the pattern and echogenicity of MNs. Radiomics features are extracted from B-mode ultrasound images (Ultrasomics), and the robust features are fed into support vector machine classifier for automated classification. The diagnostic performances of two radiologists and the CAD system are evaluated using ROC analysis.

RESULTS

The agreement of two radiologists was excellent for both guide 1 and 2. The honey-comb pattern clearly appeared in control wrists (based on guide 1). In addition, CTS wrists indicated significantly lower number of fascicles in MNs (based on guide 2). The area under ROC curve (AUC) of the radiologist 1 and 2 are 0.658 and 0.667 based on guide 1 and 0.736 and 0.721 based on guide 2, respectively. The CAD system indicated higher performance than two radiologists with AUC of 0.926.

CONCLUSION

The proposed CAD system shows the benefit of using ultrasomics features and can assist radiologists to diagnose CTS accurately.

Application of High-Resolution Ultrasound on Diagnosing Diabetic Peripheral Neuropathy

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes mellitus (DM). The typical manifestation is a length-dependent "glove and sock" sensation. At present, diagnosis is mainly dependent on clinical manifestations. Since the pathogenesis is not clear, there are no effective treatment measures. Management consists mainly of glucose control, peripheral nerve nutrition, and other measures to delay the progress of the disease; early diagnosis is therefore crucial to improving prognosis and quality of life for patients with DPN. Due to the lack of obvious symptoms in 50% of patients and the low sensitivity of neuro-electrophysiology to small fibers, the missed diagnosis rate is high. High-resolution ultrasound (HRU), as a convenient noninvasive tool, has been proven by many studies to have excellent clinical value in diagnosing DPN. With the development of related new technology, HRU shows promise for the screening, diagnosing, and follow-up of DPN, which could serve as a biomarker and provide new diagnostic insights. In this paper, we review the ability of HRU to detect nerve cross-sectional area and blood flow, and echo and other image changes, and in showing the characteristics of peripheral nerve morphological changes in patients with DPN. We also explore the application of two other recent technological developments-shear wave elastography (SWE) and ultrasound scoring systems-in improving the diagnostic efficiency of HRU in peripheral neuropathy.

Clinico-radiological review of peripheral entrapment neuropathies - Part 1 upper limb

PURPOSE

This article aims to review the pertinent anatomy, etiopathogenesis, current clinical and radiological concepts and principles of management in case of upper limb entrapment neuropathies.

METHODS

The review is based on critical analysis of the existing literature as well as our experience in dealing with entrapment neuropathies.

RESULTS

Entrapment neuropathies of the upper limb peripheral nerves are common conditions that are often misdiagnosed because of their varying clinical presentations and lack of standardized diagnostic methods. Clinical assessment and electrodiagnostic studies have been the mainstay; however, imaging techniques have provided newer insights into the pathophysiology of these entities, leading to a paradigm shift in their diagnosis and management. The current best practice protocols for entrapment syndromes are constantly evolving with increasing emphasis on the role high-resolution ultrasound and magnetic resonance imaging. Many imaging criteria are described and we have tried to present the most validated measurements for diagnosing entrapment neuropathies.

CONCLUSION

It is imperative for a clinical radiologist to be familiar with the etiopathogenesis and clinical features of these conditions, in addition to being thorough with the anatomy and the latest imaging strategies.

Anterocentral Portal in Ankle Arthroscopy

BACKGROUND

The anterocentral portal is not a standard portal in anterior ankle arthroscopy due to its proximity to the anterior neurovascular bundle. However, it provides certain advantages, including a wide field of vision, and portal changes become redundant. The purpose of this study was to evaluate the neurovascular complications after anterior ankle arthroscopy using the anterocentral portal.

METHODS

We retrospectively identified patients who had undergone anterior ankle arthroscopy with an anterocentral portal at our institution from 2013 to 2018. Medical record data were reviewed and patients were invited for clinical follow-up, where a clinical examination, quantitative sensory testing for the deep peroneal nerve, and ultrasonography of the structures at risk were performed. A total of 101 patients (105 arthroscopies) were identified and evaluated at a mean follow-up of 31.5 ± 17.7 months.

RESULTS

Leading indications to surgery were heterogeneous and included anterior impingement (48.6%), osteochondral lesions of the talus (24.8%), chronic ankle instability (14.3%), and fractures (8.6%). The overall complication rate was 7.6%, and no major complications were observed. In 1.9% (2/105) of the cases, the complications were associated with the anterocentral portal and included injury to the medial branch of the superficial nerve (1/105) and to the deep peroneal nerve (1/105). Injury to the deep peroneal nerve was associated with a loss of detection and nociception. There were no injuries to the anterior tibial artery. In 41.9% (44/105) of the cases, only 1 working portal was used in addition to the anterocentral portal, and in 19% (20/105) the anterolateral portal could be avoided. Ultrasonography confirmed the integrity of the deep peroneal nerve, the medial branch of the superficial peroneal nerve, and the anterior tibial artery in all patients. Patients with nerve injuries associated with the anterocentral portal showed no signs of neuroma or pseudoaneurysm.

CONCLUSION

Using a standardized technique, the anterocentral portal in ankle arthroscopy is safe with a low number of neurovascular injuries and can be recommended as a standard portal. The anterolateral portal remains associated with a high number of injuries to the superficial peroneal nerve.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Current and future applications of ultrasound imaging in peripheral nerve disorders

Neuromuscular ultrasound (NMUS) is a rapidly evolving technique used in neuromuscular medicine to provide complimentary information to standard electrodiagnostic studies. NMUS provides a dynamic, real time assessment of anatomy which can alter both diagnostic and management pathways in peripheral nerve disorders. This review describes the current and future techniques used in NMUS and details the applications and developments in the diagnosis and monitoring of compressive, hereditary, immune-mediated and axonal peripheral nerve disorders, and motor neuron diseases. Technological advances have allowed the increased utilisation of ultrasound for management of peripheral nerve disorders; however, several practical considerations need to be taken into account to facilitate the widespread uptake of this technique.

Assessing the Performance of Morphologic and Echogenic Features in Median Nerve Ultrasound for Carpal Tunnel Syndrome Diagnosis

OBJECTIVES

To assess the feasibility of using ultrasound (US) image features related to the median nerve echogenicity and shape for carpal tunnel syndrome (CTS) diagnosis.

METHODS

In 31 participants (21 healthy participants and 10 patients with CTS), US images were collected with a 30-MHz transducer from median nerves at the wrist crease in 2 configurations: a neutral position and with wrist extension. Various morphologic features, including the cross-sectional area (CSA), were calculated to assess the nerve shape. Carpal tunnel syndrome commonly results in loss of visualization of the nerve fascicular pattern on US images. To assess this phenomenon, we developed a nerve-tissue contrast index (NTI) method. The NTI is a ratio of average brightness levels of surrounding tissue and the median nerve, both calculated on the basis of a US image. The area under the curve (AUC) from a receiver operating characteristic curve analysis and t test were used to assess the usefulness of the features for differentiation of patients with CTS from control participants.

RESULTS

We obtained significant differences in the CSA and NTI parameters between the patients with CTS and control participants (P < .01), with the corresponding highest AUC values equal to 0.885 and 0.938, respectively. For the remaining investigated morphologic features, the AUC values were less than 0.685, and the differences in means between the patients and control participants were not statistically significant (P > .10). The wrist configuration had no impact on differences in average parameter values (P > .09).

CONCLUSIONS

Patients with CTS can be differentiated from healthy individuals on the basis of the median nerve CSA and echogenicity. Carpal tunnel syndrome is not manifested in a change of the median nerve shape that could be related to circularity or contour variability.

Strategies for Peripheral Nerve Repair

PURPOSE OF REVIEW

This review focuses on biomechanical and cellular considerations required for development of biomaterials and engineered tissues suitable for implantation following PNI, as well as translational requirements relating to outcome measurements for testing success in patients.

RECENT FINDINGS

Therapies that incorporate multiple aspects of the regenerative environment are likely to be key to improving therapies for nerve regeneration. This represents a complex challenge when considering the diversity of biological, chemical and mechanical factors involved. In addition, clinical outcome measures following peripheral nerve repair which are sensitive and responsive to changes in the tissue microenvironment following neural injury and regeneration are required.

SUMMARY

Effective new therapies for the treatment of PNI are likely to include engineered tissues and biomaterials able to evoke a tissue microenvironment that incorporates both biochemical and mechanical features supportive to regeneration. Translational development of these technologies towards clinical use in humans drives a concomitant need for improved clinical measures to quantify nerve regeneration.

Radiomics of peripheral nerves MRI in mild carpal and cubital tunnel syndrome

OBJECTIVE

To assess the discriminative power of radiomics of peripheral nerves at 1.5T MRI, using common entrapment neuropathies of the upper limb as a model system of focal nerve injury.

MATERIALS AND METHODS

Radiomics was retrospectively done on peripheral nerve fascicles on T1-weighted 1.5T MRI of 40 patients with diagnosis of mild carpal (n = 25) and cubital tunnel (n = 15) syndrome and of 200 controls. Z-score normalization and Mann-Whitney U test were used to compare features of normal and pathological peripheral nerves. Receiver operating characteristic analysis was performed.

RESULTS

A total of n = 104 radiomics features were computed for each patient and control. Significant differences between normal and pathological median and ulnar nerves were found in n = 23/104 features (p < 0.001). According to features classification, n = 5/23 features were shape-based, n = 7/23 were first-order features, n = 11/23 features were classified as gray level run length matrix. Nine of the selected features showed an AUC higher that 0.7: minimum AUC of 0.74 (95% CI 0.61-0.89) for sum variance and maximum AUC of 0.90 (95% CI 0.82-0.99) for zone entropy.

CONCLUSION

Features analysis demonstrated statistically significant differences between normal and pathological nerve. The results suggested that radiomics analysis could assess the median and ulnar nerve inner structure changes due to the loss of the fascicular pattern, intraneural edema, fibrosis or fascicular alterations in mild carpal tunnel and mild cubital tunnel syndromes even when the nerve cross-sectional area does not change.

Retrospective study on the impact of ulnar nerve dislocation on the pathophysiology of ulnar neuropathy at the elbow

Introduction

High resolution ultrasonography (US) has been used for diagnosis and evaluation of entrapment peripheral neuropathy. Ulnar neuropathy at the elbow (UNE) is the second most common focal entrapment neuropathy. The ulnar nerve tends to move to the anteromedial side and sometimes subluxates or dislocates over the medial epicondyle as the elbow is flexed. Dislocation of the ulnar nerve during elbow flexion may contribute to friction injury. We aimed to investigate the effects which the dislocation of ulnar nerve at the elbow could have on the electrophysiologic pathology of UNE.

Materials

We retrospectively reviewed 71 arms of UNE. The demographic data, electrodiagnosis findings and US findings of ulnar nerve were analyzed. We classified the electrodiagnosis findings of UNE into three pathologic types; demyelinating, sensory axonal loss, and mixed sensorimotor axonal loss. The arms were grouped into non-dislocation, partial dislocation, and complete dislocation groups according to the findings of nerve dislocation in US examination. We compared the electrodiagnosis findings, ulnar nerve cross sectional areas in US and electrodiagnosis pathology types among the groups.

Results

A total of 18 (25.3%) arms showed partial dislocation, and 15 (21.1%) arms showed complete dislocation of ulnar nerve in US. In the comparison of electrodiagnosis findings, the partial and complete dislocation groups showed significantly slower conduction velocities and lower amplitudes than non-dislocation group in motor conduction study. In the sensory conduction study, the conduction velocity was significantly slower in partial dislocation group and the amplitude was significantly lower in complete dislocation group than non-dislocation group. In the comparison of US findings, patients in partial and complete dislocation groups showed significantly larger cross sectional areas of the ulnar nerve. The comparison of electrodiagnosis pathologic types among the groups revealed that there were significantly larger proportions of the axonal loss (sensory axonal loss or mixed sensorimotor axonal loss) in partial and complete dislocation groups than non-dislocation group.

Conclusion

The ulnar nerve dislocation could influence on the more severe damage of the ulnar nerve in patients with UNE. It might be important to evaluate the dislocation of the ulnar nerve using US in diagnosing ulnar neuropathy for predicting the prognosis and determining the treatment direction of UNE.

Deployment of acute mechanical circulatory support devices via the axillary artery

Introduction: Use of acute mechanical circulatory support (MCS) devices for high-risk cardiac intervention, cardiogenic shock, and advanced heart failure is growing. Alternate vascular access options for these devices remains a clinical challenge. Building on experience from trans-aortic valve replacement procedures, the axillary artery is becoming a common access route for acute MCS and represents an important advance in the development of acute MCS technologies. Areas covered: Authors review the clinical data and technical aspect of acute MCS deployment via the axillary artery. Axillary access is particularly useful for patients: 1) with severe peripheral vascular disease, 2) with hostile femoral access due to infection, indwelling endovascular devices, or obesity, and 3) to provide early mobility and ambulation. In this review, we discuss the deployment, technical issues and hemostasis regarding the use of intraaortic balloon pump, specifically, axillary intraaortic balloon pumps, trans-valvular left ventricular Impella pumps and arterial outflow of VA-ECMO. Expert opinion: Vascular comorbidities or device design may limit the traditional iliofemoral access route for acute mechanical circulatory support devices. Large bore access for the deployment of these devices through the axillary artery is feasible and safe when appropriate vascular access and closure techniques are used.

Ultrasound in the Evaluation of Radial Neuropathies at the Elbow

There are five sites at which radial nerve entrapment at the elbow has been commonly reported. These include the level of the fibrous bands within the extensor carpi radialis brevis, the thickened fascial tissue at the radiocapitellar joint, the leash of Henry, the arcade of Frohse, and the distal border of the supinator muscle. This review describes the anatomy of the radial nerve at the elbow and the surrounding structures, and then provides an overview of the literature supporting the use of ultrasound to assist in the evaluation of suspected radial neuropathy at the elbow. This review concludes with a suggested ultrasonographic approach for the systematic evaluation of suspected radial neuropathy at the elbow.

Shear wave elastography evaluation of the median and tibial nerve in diabetic peripheral neuropathy

Background

To evaluate the value of shear wave elastography (SWE) in the detection of diabetic peripheral neuropathy (DPN) of the median and tibial nerves.

Methods

The study included 40 DPN patients, 40 diabetic mellitus (DM) patients without DPN, and 40 healthy subjects. High-resolution ultrasonography (US) and SWE were performed on the median nerve (MN) and tibial nerve (TN), and cross-sectional area (CSA) and nerve stiffness were measured. ROC analysis was also performed.

Results

The patients with DPN demonstrated higher stiffness of the median and tibial nerve compared with that of healthy volunteers and DM patients (P<0.001). Bilateral analysis showed that there was no significant difference in nerve stiffness between the left and right median nerves and tibial nerves in DPN patients (P>0.05). The stiffness of median nerve and tibial nerve in each one side also had no significant difference in patients with DPN (P>0.05). The CSA of the tibial nerve in the DPN group was significantly larger than that in the other groups (P<0.001), while there was no significant difference of median nerve CSA among the three groups (P>0.05). The area under curve (AUC) of SWE (MN: 0.899, TN: 0.927) to diagnose DPN was significantly greater than that of CSA (TN: 0.798). The optimal cut-off value in SWE of the tibial nerve and median nerve for diagnosis of DPN was 4.11 and 4.06 m/s, respectively, with a good sensitivity and specificity.

Conclusions

Median and tibial nerve stiffness was significantly higher in patients with DPN. These findings suggest that SWE-based stiffness measurement of the nerve was a better method than CSA, and it can be used as another effective assistant method in the diagnosis of DPN.

Relationship between sonographically measured median nerve cross-sectional area and presence of peripheral neuropathy in diabetic subjects

BACKGROUND

Neuropathy is a common complication of diabetes mellitus resulting from direct damage by hyperglycemia to the nerves and/or ischemia by microvascular injury to the endoneurial vessels which supply the nerves. Median nerve is one of the peripheral nerves commonly affected in diabetic neuropathy. The median nerve size has been studied in non-Nigerian diabetic populations. In attempt to contribute to existing literature, a study in a Nigerian population is needed.

AIM

To evaluate the cross-sectional area (CSA) of the median nerve using B-mode ultrasonography (USS) and the presence of peripheral neuropathy (PN) in a cohort of adult diabetic Nigerians.

METHODS

Demographic and anthropometric data of 85 adult diabetes mellitus (DM) and 85 age- and sex-matched apparently healthy control (HC) subjects were taken. A complete physical examination was performed on all study subjects to determine the presence of PN and modified Michigan Neuropathy Screening Instrument (MNSI) was used to grade its severity. Venous blood was taken from the study subjects for fasting lipid profile (FLP), fasting blood glucose (FBG) and glycated haemoglobin (HbA1c) while their MN CSA was evaluated at a point 5 cm proximal to (5cmCATL) and at the carpal tunnel (CATL) by high-resolution B-mode USS. Data was analysed using SPSS version 22.

RESULTS

The mean MN CSA was significantly thicker in DM subjects compared to the HC at 5cmCATL (P < 0.01) and at the CATL (P < 0.01) on both sides. The presence of diabetic peripheral neuropathy (DPN) further increased the MN CSA at the CATL (P < 0.05) but not at 5cmCATL (P > 0.05). However, the severity of DPN had no additional effect on MN CSA 5 cm proximal to and at the CATL. There was no significant association between MN CSA and duration of DM and glycemic control.

CONCLUSION

Thickening of the MN CSA at 5cmCATL and CATL is seen in DM. Presence of DPN is associated with worse thickening of the MN CSA at the CATL but not at 5cmCATL. Severity of DPN, duration of DM, and glycemic control had no additional effect on the MN CSA.