Reference values for nerve ultrasonography in the upper extremity

Nerve cross-sectional area from childhood to old age: A high-resolution nerve ultrasound study

BACKGROUND AND PURPOSE

Nerve cross-sectional area (CSA) is not constant over the human lifespan. The relationship between an increasing CSA and age has been described as a linear positive correlation, but few studies have found a linear decrease in nerve size with older age. The aim of the present study was to analyze the development of nerve CSA in a healthy population from early childhood to old age using high-resolution ultrasound.

METHODS

The median, ulnar, radial and sural nerves were examined bilaterally at 18 nerve sites in 110 healthy children, adolescents and adults aged between 2 and 98 years. The CSA of every nerve site was evaluated separately and in different age groups. The correlation of CSA with age, height and weight was analyzed in a linear, logarithmic and quadratic model and correlation coefficients were compared in a goodness-of-fit analysis. Models were then adjusted for weight and height.

RESULTS

Linear CSA-age correlations showed the lowest correlation coefficients for all nerve sites. An inverted parabolic curve suggesting a quadratic correlation of CSA and age was the best-fitting model. Weight and height had a higher predictive value than age in adjusted models.

CONCLUSIONS

There is an increase in nerve size during childhood and adolescence and a trend towards a decrease in old age, suggesting an inverted parabolic curve partly explained by age-related changes in weight and height. Enlarged nerves in elderly individuals should not be attributed to age alone.

A case report of neuralgic amyotrophy

Neuralgic muscular atrophy is not uncommon in clinical practice. Due to the different branches of brachial plexus involved in the lesion, the clinical symptoms are different, and there is a lack of clear imaging diagnostic criteria, so the diagnosis of this disease brings great challenges to clinicians. We have certain experience in the diagnosis and treatment of this disease, and hereby select a representative case of neuralgic muscular atrophy to share its diagnosis and treatment process, focusing on analyzing the characteristic symptoms of this disease, valuable imaging data and targeted treatment, so as to enable clinicians to better understand this disease.

Neuromuscular ultrasound findings in gunshot wounds

INTRODUCTION/AIMS

A spectrum of peripheral nerve injuries is associated with gunshot wounds (GSWs). Due to Wallerian degeneration, distal nerve lesions may go undetected on electrodiagnostic (EDX) testing. In patients with GSW undergoing high-resolution ultrasound (HRUS) for evaluation of neurological deficits, we have observed distal nerve morphological changes, but these have not been systematically studied. The aim of this study was to characterize changes on HRUS in nerves at and distal to gunshot injuries and to identify the frequency with which these changes occur.

METHODS

A retrospective cohort study was performed on patients referred for HRUS with peripheral nerve injuries from GSW. The primary injured nerve(s) were assessed along with distal segments of the same nerve and those of adjacent nerves. Findings were also compared to EDX studies.

RESULTS

Twenty-two of the 28 nerves injured proximally by GSW were evaluated distally and of these, 68% showed abnormal ultrasound findings, including enlarged cross sectional area (59%), fascicular enlargement (50%), and decreased nerve echogenicity (59%). In 17 patients, adjacent nerves were evaluated and 8 of the patients (47%) showed abnormalities in at least one distal adjacent nerve, including enlarged cross sectional area (41%), fascicular enlargement (41%), and decreased nerve echogenicity (35%).

DISCUSSION

This study demonstrated morphological changes at the site of the GSW but also in distal nerve segments including nerve enlargement, fascicular enlargement, and changes in nerve echogenicity. The complementary use of HRUS with EDX was highlighted in evaluation of GSW victims to assess the extent of peripheral nerve injury.

Sonographic reference values for median nerve cross-sectional area: A meta-analysis of data from healthy individuals

Objective

Establish median nerve CSA reference values and identify patient-level factors impacting diagnostic thresholds.

Methods

Studies were identified through a robust search of multiple databases, and quality assessment was conducted using a modified version of the National Institute of Health Study Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. A meta-analysis was performed to identify normative values stratified by anatomic location. A meta-regression was conducted to examine heterogeneity effects of age, sex, and laterality.

Results

The meta-analysis included 73 studies; 41 (56.2%) were high quality. The median nerve CSA [95% CI] was 6.46mm2 [6.09-6.84], 8.68mm2 [8.22-9.13], and 8.60mm2 [8.23-8.97] at the proximal forearm, the carpal tunnel inlet, and the proximal carpal tunnel, respectively. Age was positively associated with CSA at the level of proximal carpal tunnel (β=0.03mm2, p=0.047). Men (9.42mm2, [8.06-10.78]) had statistically larger proximal tunnel CSA (p = 0.03) as compared to women (7.71mm2, [7.01-8.42]). No difference was noted in laterality.

Conclusion

A reference value for median nerve CSA in the carpal tunnel is 8.60mm2. Adjustments may be required in pediatrics or older adults. The diagnostic threshold of 10.0mm2 for male patients should be cautiously applied as the upper limit of normative averages surpasses this threshold.

Nerve ultrasound reference values in children and adolescents: Echogenicity and influence of anthropometric factors including hand volume

Background

Nerve cross-sectional area (CSA) reference values in high-resolution ultrasound for children and adolescents are influenced by demographic and anthropometric factors such as age, height and weight.

Objectives

The influence of hand volume as an additional morphometric factor was evaluated and nerve echogenicity was analyzed in a prospective cross-sectional study.

Methods

CSA were measured in 30 healthy children and adolescents from 2 to 17 years in the median, ulnar, radial, tibial, peroneal and sural nerves. Height, weight, age, handedness and gender were recorded, the volume of the hands was measured using the water displacement method. The intra-nerve CSA variability (INV), left/right ratios and absolute differences were calculated. Age groups were compared by the Kruskal-Wallis test. The influence of demographic factors was analyzed using Spearman correlation and multiple linear regression. Echogenicity and fraction of black were determined for each nerve segment.

Results

Nerve CSA values were consistently lower than those reported for adults and correlated in all measured nerve sites with age, height, weight and hand volume. Weight showed the highest correlation coefficient (R = .95) with the best fitting model predicting CSA. Correlation coefficients were higher in a linear than in a logarithmic model. Ratios were stable, the absolute differences increased with age and were significantly different between age groups. Most nerves showed a mixed or hypoechogenic pattern in echogenicity analysis, hyperechogenicity is less frequently observed.

Conclusions

Nerve CSA in children and adolescents is lower than in adults and increases proportionally during growth with a constant INV and left/right ratio in different age groups. Weight and age are predominant anthropometric factors predicting nerve size. Hand volume is correlated with nerve size, but does not predict CSA independently. Echogenicity can provide additional information on nerve structure.

Pressure Pain Hypersensitivity and Ultrasound Changes in the Radial Nerve in Patients with Unilateral Lateral Epicondylalgia: A Case-Control Study

Some authors have proposed the potential role of the radial nerve in lateral epicondylalgia. The aims of this study were to investigate the presence of pressure pain hyperalgesia and nerve swelling (increased cross-sectional area) assessed with ultrasound imaging on the radial nerve in people with lateral epicondylalgia, and to investigate if an association exists between pressure pain sensitivity and cross-sectional area. A total of 37 patients with lateral epicondylalgia (43% women, age: 45.5 ± 9.5 years) and 37 age- and sex-matched pain-free controls were recruited for participation. Pressure pain thresholds (PPTs) were assessed bilaterally on the radial nerve at the spiral groove, the arcade of Frohse, and the anatomic snuffbox in a blinded design. Further, the cross-sectional area of the radial nerve at the spiral groove and antecubital fossa was also assessed. The results demonstrated lower PPTs on the radial nerve of the affected side in individuals with lateral epicondylalgia as compared with the unaffected side (p < 0.01) and with both sides in healthy controls (p < 0.001). Additionally, the cross-sectional area of the radial nerve on the affected side in patients was higher compared with the unaffected side (p < 0.01) and both sides in healthy controls (p < 0.001). The cross-sectional area of the radial nerve at the spiral groove was negatively associated with PPTs over the radial nerve at the spiral groove (r = -0.496, p = 0.002) and positively associated with function (r = 0.325, p = 0.045). Our findings revealed generalized pressure pain hyperalgesia and also nerve swelling of the radial nerve in people with lateral epicondylalgia, suggesting the presence of a widespread sensitization of nerve tissues in this population. The radial nerve could represent a potential peripheral drive to initial and maintain altered pain processing in lateral epicondylalgia.

Sonographic peripheral nerve cross-sectional area in adults, excluding median and ulnar nerves: A systematic review and meta-analysis

INTRODUCTION/AIMS

Although electromyography remains the "gold standard" for assessing and diagnosing peripheral nerve disorders, ultrasound has emerged as a useful adjunct, providing valuable anatomic information. The objective of this study was to conduct a systematic review and meta-analysis evaluating the normative sonographic values for adult peripheral nerve cross-sectional area (CSA).

METHODS

Medline and Cochrane Library databases were systematically searched for healthy adult peripheral nerve CSA, excluding the median and ulnar nerves. Data were meta-analyzed, using a random-effects model, to calculate the mean nerve CSA and its 95% confidence interval (CI) for each nerve at a specific anatomical location (= group).

RESULTS

Thirty groups were identified and meta-analyzed, which comprised 16 from the upper extremity and 15 from the lower extremity. The tibial nerve (n = 2916 nerves) was reported most commonly, followed by the common fibular nerve (n = 2580 nerves) and the radial nerve (n = 2326 nerves). Means and 95% confidence interval (CIs) of nerve CSA for the largest number of combined nerves were: radial nerve assessed at the spiral groove (n = 1810; mean, 5.14 mm2 ; 95% CI, 4.33 to 5.96); common fibular nerve assessed at the fibular head (n = 1460; mean, 10.18 mm2 ; 95% CI, 8.91 to 11.45); and common fibular nerve assessed at the popliteal fossa (n = 1120; mean, 12.90 mm2 ; 95% CI, 9.12 to 16.68). Publication bias was suspected, but its influence on the results was minimal.

DISCUSSION

Two hundred thirty mean CSAs from 15 857 adult nerves are included in the meta-analysis. These are further categorized into 30 groups, based on anatomical location, providing a comprehensive reference for the clinician and researcher investigating adult peripheral nerve anatomy.

Clinical, Electrophysiological, and Sonographic Findings in Patients With Nerve Injury After Vessel Puncture

BACKGROUND AND PURPOSE

This study aimed to describe the clinical, electrophysiological, and ultrasonographic findings of patients with nerve injury after vessel puncture.

METHODS

Data on ten patients (three males and seven females) with nerve injury after vessel puncture were reviewed. Demographic and clinical data were analyzed retrospectively. Bilateral electrophysiological studies were performed based on clinical findings. Ultrasonographic examinations were performed on both the affected and unaffected sides of the injured nerve.

RESULTS

The nerves of nine patients were injured following vein puncture, and injury occurred following arterial sampling in one patient. Seven patients had superficial radial sensory nerve injury: five medial, one lateral, and one at both branches. One patient had injury to the dorsal ulnar cutaneous nerve, one to the lateral antebrachial cutaneous nerve, and one to the median nerve. Nerve conduction studies produced abnormal findings in 80% of patients, whereas ultrasonographic examinations produced abnormal findings in all of the patients. Spearman's coefficient for the correlation between the amplitude ratio and nerve cross-sectional area ratio was not significant, at -0.127 (95% confidence interval=-0.701 to 0.546, p=0.721).

CONCLUSIONS

Ultrasonography supported by electrodiagnosis was found to be a useful method for identifying the lesion location and structural abnormalities of vessel-puncture-related neuropathy.

Diagnostic Considerations in Compressive Neuropathies

Peripheral nerve compression of the upper extremity is a common pathology often necessitating surgical intervention, much is known, but much more is left to understand. For the more common pathologies, carpal tunnel syndrome, cubital tunnel syndrome, and ulnar tunnel syndrome, research and clinical efforts directed toward standardization and reduction of resource use have been attempted with varied success. Diagnosis of many of these syndromes is largely based on a proper history and physical examination. Electrodiagnostic studies continue to have value, but proportionally less than previous decades. In addition, emerging technologies, including magnetic resonance neurography, novel ultrasound evaluation techniques, and ultrasound-guided diagnostic injections, are beginning to demonstrate their ability to add value to the diagnostic algorithm, particularly when less common compressive neuropathies are present and/or the diagnosis is in question.

The cross-sectional morphology of median nerve in carpal tunnel of healthy, adult population: A systematic review and meta-analysis

The cross-section area is a crucial parameter to assess peripheral neuropathy. The ultrasonographic evaluation of cross-section area of median nerve is a low-cost and readily available tool for diagnosis and assessment. However, the intra-nerve dimensional variability and its normative reference value in a healthy subject are missing. The current meta-analysis aims to capture the median nerve cross-section area for healthy subjects and generate a comprehensive ultrasonographic reference data set for each population.

METHODS

The full text of manuscripts were collected after short-listing the abstracts collected from search strategy. A quality assurance tool was used to capture the risk of bias of each study after reviewing the included manuscripts. The pooled estimate of cross-section area was stratified according to anatomical landmarks, sex, and ancestry.

RESULTS

A total of 97 observational studies dealt with 6679 wrists of healthy subjects were included. The pooled estimate of the cross-section area of median nerve at carpal tunnel inlet was 8.54mm² [95% CI: 8.34-8.74mm²]. The same pooled estimate at carpal tunnel outlet was 8.03mm² [95% CI: 7.46-8.60mm²]. Both these pooled estimates have significant correlation with mean age of population. Age and sex were two primary predictors of the cross-section of median nerve. The flattening ratio, circularity, and wrist-forearm ratio of median nerve were also computed.

CONCLUSION

These normative data could serve as a reference for assessing median nerve pathologies, including carpal tunnel syndrome. The ethnic variation of pooled estimate and heterogeneity will guide clinician set up the reference value for diagnostic criteria.

Ulnar nerve thickness at the elbow on longitudinal ultrasound view in control subjects

INTRODUCTION

Ulnar mononeuropathy at the elbow is the second most frequent neuropathy in humans. Diagnosis is based on clinical and electrophysiological criteria and, more recently, also on ultrasound. Cross-sectional ultrasound is currently the most valued, although longitudinal ultrasound allows assessment of the entire affected trajectory of the nerve in a single view, but always in a straight line with no changes in direction, as in the extended elbow. The main aim of this work is to propose normative values ​​for longitudinal ultrasound of the ulnar nerve at the elbow.

METHODS

The neurological exploration of upper extremity, and electrophysiological and ultrasound parameters at the elbow of ulnar nerve were evaluated in 76 limbs from 38 asymptomatic subjects.

RESULTS

The diameters of the nerve as well as the distal and proximal areas were larger at the proximal region of the ulnar groove, and even more so in older individuals. In most of these elderly subjects, we found a small, non-significant slowdown in motor conduction velocity at the elbow with respect to the forearm (less than 5 m/s).

CONCLUSIONS

We observed a good correlation between the longitudinal and cross-sectional ultrasounds of the ulnar nerve at the elbow. Longitudinal ultrasound proved to be sensitive, reliable, simple and rapid, but its greatest contribution was allowing the visualization of the entire nerve trajectory in an integrated way, providing an image with good definition of the outline, proportions and intraneural characteristics of the nerve.

A standardized ultrasound approach in neuralgic amyotrophy

Neuralgic amyotrophy (NA), also referred to as idiopathic brachial plexitis and Parsonage-Turner syndrome, is a peripheral nerve disorder characterized by acute severe shoulder pain followed by progressive upper limb weakness and muscle atrophy. While NA is incompletely understood and often difficult to diagnose, early recognition may prevent unnecessary tests and interventions and, in some situations, allow for prompt treatment, which can potentially minimize adverse long-term sequalae. High-resolution ultrasound (HRUS) has become a valuable tool in the diagnosis and evaluation of NA. Pathologic HRUS findings can be grouped into four categories: nerve swelling, swelling with incomplete constriction, swelling with complete constriction, and fascicular entwinement, which may represent a continuum of pathologic processes. Certain ultrasound findings may help predict the likelihood of spontaneous recovery with conservative management versus the need for surgical intervention. We recommend relying heavily on history and physical examination to determine which nerves are clinically affected and should therefore be assessed by HRUS. The nerves most frequently affected by NA are the suprascapular, long thoracic, median and anterior interosseous nerve (AIN) branch, radial and posterior interosseous nerve (PIN) branch, axillary, spinal accessory, and musculocutaneous. When distal upper limb nerves are affected (AIN, PIN, superficial radial nerve), the lesion is almost always located in their respective fascicles within the parent nerve, proximal to its branching point. The purpose of this review is to describe a reproducible, standardized, ultrasonographic approach for evaluating suspected NA, and to share reliable techniques and clinical considerations when imaging commonly affected nerves.

Diagnostic accuracy of nerve ultrasonography for the detection of peripheral neuropathy in type 2 diabetes

BACKGROUND AND PURPOSE

Nerve conduction studies (NCS) are the current objective measure for diagnosis of peripheral neuropathy in type 2 diabetes but do not assess nerve structure. This study investigated the utility of peripheral nerve ultrasound as a marker of the presence and severity of peripheral neuropathy in type 2 diabetes.

METHODS

A total of 156 patients were recruited, and nerve ultrasound was undertaken on distal tibial and distal median nerves. Neuropathy severity was graded using the modified Toronto Clinical Neuropathy Scale (mTCNS) and Total Neuropathy Score (TNS). Studies were undertaken by a single ultrasonographer blinded to nerve conduction results.

RESULTS

A stepwise increase in tibial nerve cross-sectional area (CSA) was noted with increasing TNS grade (p &lt; 0.001) and each mTCNS quartile (p &lt; 0.001). Regression analysis demonstrated a correlation between tibial nerve CSA and neuropathy severity (p &lt; 0.001). Using receiver operator curve analysis, tibial nerve CSA of &gt;12.88 mm yielded a sensitivity of 70.5% and specificity of 85.7% for neuropathy detection. Binary logistic regression revealed that tibial nerve CSA was a predictor of abnormal sural sensory nerve action potential amplitude (odds ratio = 1.239, 95% confidence interval [CI] = 1.142-1.345) and abnormal neuropathy score (odds ratio = 1.537, 95% confidence interval [CI] = 1.286-1.838).

CONCLUSIONS

Tibial nerve ultrasound has good specificity and sensitivity for neuropathy diagnosis in type 2 diabetes. The study demonstrates that tibial nerve CSA correlates with neuropathy severity. Future serial studies using both ultrasound and NCS may be useful in determining whether changes in ultrasound occur prior to development of nerve conduction abnormalities and neuropathic symptoms.

A Novel Ultrasonographic Anthropometric-Independent Measurement of Median Nerve Swelling in Carpal Tunnel Syndrome: The "Nerve/Tendon Ratio" (NTR)

Background: There is little consensus on ultrasound (US) normative values of cross-sectional area of median nerve (MN-CSA) in carpal tunnel syndrome (CTS) because of its dependency on anthropometric parameters. We aim to propose a novel anthropometric-independent US parameter: MN-CSA/flexor radialis carpi CSA (FCR-CSA) ratio (“Nerve Tendon Ratio”, NTR), in the diagnosis of clinically and electrodiagnostic (EDS)-defined CTS. Methods: 74 wrists of 49 patients with clinically defined CTS underwent EDS (scored by the 1−5 Padua Scale of electrophysiological severity, PS) and US of carpal tunnel with measurement of MN-CSA (at the carpal tunnel inlet), FCR-CSA (over scaphoid tubercle) and its ratio (NTR, expressed as a percentage). US normality values and intra-operator agreement were assessed in 33 healthy volunteers. Results: In controls, the mean MN-CSA was 5.81 mm2, NTR 64.2%. In 74 clinical CTS, the mean MN-CSA was 12.1 mm2, NTR 117%. In severe CTS (PS > 3), the mean MN-CSA was 15.9 mm2, NTR 148%. In CTS, both MN-CSA and NTR correlated with sensitive conduction velocity (SCV) (p < 0.001), distal motor latency (DML) (p < 0.001) and PS (p < 0.001), with a slight superiority of NTR vs. MN-CSA when controlled for height, wrist circumference and weight. In CTS filtered for anthropometric extremes, only NTR maintained a correlation with SCV (p = 0.023), DML (p = 0.016) and PS (p = 0.009). Diagnostic cut-offs were obtained with a binomial regression analysis. In those patients with a clinical diagnosis of CTS, the cut-off of MN-CSA (AUROC: 0.983) was 8 mm2 (9 mm2 with highest positive predictive value, PPV), while for NTR (AUROC: 0.987), the cut-off was 83% (100% with highest PPV). In patients with EDS findings of severe CTS (PS > 3), the MN-CSA (AUROC: 0.876) cut-off was 12.3 mm2 (15.3 mm2 with highest PPV), while for NTR (AUROC: 0.858) it was 116.2% (146.0% with highest PPV). Conclusions: NTR can be simply and quickly calculated, and it can be used in anthropometric extremes.

Normative Value of the Cross-Sectional Area of the Median Nerve at the Carpal Tunnel Inlet and Distal Forearm in the Singapore Population

Background: Ultrasonography is often used in the diagnosis of carpal tunnel syndrome (CTS). However, we were unable to find normative data regarding the cross-sectional area (CSA) of the median nerve in the Singapore population as measured by ultrasound. The aims of this study were to establish normative values of the CSA of the median nerve at the carpal tunnel inlet in a healthy population, 5 cm proximal to the carpal tunnel inlet, and to determine if the CSA correlated with side, age, gender or race.

Methods: Sixty-nine wrists of 36 healthy subjects with no history of wrist injury or any signs and symptoms of CTS were examined. The CSA of the median nerve at the carpal tunnel inlet and 5 cm proximal to the carpal tunnel inlet was determined using ultrasound by a trained operator.

Results: The mean CSA of the median nerve at the carpal tunnel inlet was 6.41 mm2 (SD 2.18 mm2). These were not significantly different from the values for mean CSA obtained 5 cm proximal to the carpal tunnel inlet. We did not find any correlation between the CSA of the median nerve and age, gender or race.

Conclusions: The mean CSA of the median nerve at the carpal tunnel inlet in normal subjects in Singapore was found to be lower than other Asian populations. Wide variations of the median nerve CSA at the carpal tunnel inlet exists in the literature, and this is probably due to the heterogeneity of the study methodology and population.

Level of Evidence: Level III (Diagnostic)

Cross-sectional area reference values for high-resolution ultrasonography of the lower extremity nerves in healthy Korean adults

The cross-sectional area (CSA) reference values of the lower extremity nerves in Asians have been rarely reported. For this study, 107 sex- and age-matched, healthy subjects with a mean age of 46 years (range, 24-75 years) were recruited. All subjects underwent standardized nerve conduction studies of the upper and lower extremities. The CSA was measured unilaterally at 12 sites in the lower extremity nerves, including the femoral, lateral femoral cutaneous, sciatic, common peroneal, superficial peroneal, deep peroneal, tibial, and sural nerves. The CSA significantly correlated with height, weight, and body mass index. The CSA was significantly larger in males than females at most nerves except for the lateral femoral cutaneous, common peroneal (fibular head), and superficial peroneal nerves (distal calf). There was no statistically significant difference between the age groups except for the tibial nerve (ankle). The results of this study provide CSA reference values for the lower extremity nerves including small branches and the values can be useful in the ultrasonographic investigation of various peripheral neuropathies in East Asian populations.

A systematic review: normative reference values of the median nerve cross-sectional area using ultrasonography in healthy individuals

Median nerve cross-sectional area (CSA) was used for screening and diagnosis of neuropathy, but few studies have suggested reference range. Hence, this systematic review was performed to evaluate a normative values of median nerve CSA at various landmarks of upper limb based on ultrasonography. PubMed and Web of science were used to search relevant articles from 2000 to 2020. Forty-one eligible articles (2504 nerves) were included to access median nerve CSA at different landmarks (mid-arm, elbow, mid-forearm, carpal tunnel (CT) inlet and CT outlet). Data was also stratified based on age, sex, ethnicity, geographical location, and method of measurement. Random effects model was used to calculate pooled weighted mean (95% confidence interval (CI), [upper bound, lower bound]) at mid-arm, elbow, mid-forearm, CT inlet and outlet which found to be 8.81 mm², CI [8.10, 9.52]; 8.57 mm² [8.00, 9.14]; 7.07 mm² [6.41, 7.73]; 8.74 mm² [8.45, 9.03] and 9.02 mm² [8.08, 9.95] respectively. Median nerve CSA varies with age, geographical location, and sex at all landmarks. A low (I² < 25%) to considerable heterogeneity (I² > 75%) was observed, indicating the variation among the included studies. These findings show that median nerve CSA is varying not only along its course but also in other sub-variables.

Scale-attentional U-Net for the segmentation of the median nerve in ultrasound images

Purpose

The aim of this study was to develop a neural network that accurately and effectively segments the median nerve in ultrasound (US) images.

Methods

In total, 1,305 images of the median nerve of 123 normal subjects were used to train and evaluate the model. Four datasets from two measurement regions (wrist and forearm) of the nerve and two US machines were used. The neural network was designed for high accuracy by combining information at multiple scales, as well as for high efficiency to prevent overfitting. The model was designed in two parts (cascaded and factorized convolutions), followed by self-attention over scale and channel features. The precision, recall, dice similarity coefficient (DSC), and Hausdorff distance (HD) were used as performance metrics. The area under the receiver operating characteristic curve (AUC) was also assessed.

Results

In the wrist datasets, the proposed network achieved 92.7% and 90.3% precision, 92.4% and 89.8% recall, DSCs of 92.3% and 89.7%, HDs of 5.158 and 4.966, and AUCs of 0.9755 and 0.9399 on two machines. In the forearm datasets, 79.3% and 87.8% precision, 76.0% and 85.0% recall, DSCs of 76.1% and 85.8%, HDs of 5.206 and 4.527, and AUCs of 0.8846 and 0.9150 were achieved. In all datasets, the model developed herein achieved better performance in terms of DSC than previous U-Net-based systems.

Conclusion

The proposed neural network yields accurate segmentation results to assist clinicians in identifying the median nerve.

Normative Values for the Sonographic Measurement of the Pediatric Median and Ulnar Nerves

RATIONAL AND OBJECTIVES

Ultrasound investigation of peripheral nerves, long used in the adult population, has been shown to be of value in diagnosing a variety of peripheral nerve abnormalities. More recently, nerve sonography has also been shown to be of use in pediatrics. However, normative values for nerve size in children have been lacking. As such, the goal of this research was to establish normative data for cross sectional area (CSA) measurements of the median and ulnar nerves in children.

MATERIALS AND METHODS

The median and ulnar nerves of 48 children ranging in age from 2 years to 17 years were imaged by ultrasound. CSA measurements were made at 2 separate sites for each nerve and measured independently by 6 pediatric radiologists. Reliability of ultrasound measurements between the radiologists was assessed by calculating intraclass correlation coefficients. Linear mixed-effects modeling was performed to develop prediction models for nerve cross sectional area for each nerve segment; 95% prediction values were generated from these models to approximate normal ranges.

RESULTS

Agreement in nerve cross-sectional area measurements among the 6 radiologists for all nerve segments was good (ICC 0.82, 95% CI 0.78 to 0.85). CSA for both the median and ulnar nerves is larger in older children. However, statistical models to predict CSA using height perform better rather than those using a child's age. The range of normal nerve segment CSA using these prediction models based on child height are reported.

CONCLUSION

Median and ulnar nerve CSA can be reliably measured with ultrasound. Normal reference values for ulnar and median nerve CSA correlate with patient age but may be more optimally determined based on a child's height.

Changes in Cross-Sectional Area of the Median Nerve and Body Composition Parameters after Treatment of Acromegaly: 1 year Follow-Up

OBJECTIVE

Median neuropathy is a common manifestation of acromegaly, although its pathology is uncertain. Changes in levels of growth hormone (GH) and insulin-like growth factor I (IGF-I) and body composition are potential parameters in pathology of median neuropathy in acromegaly. We aimed to assess changes in the cross-sectional area (CSA) of the median nerve and body composition in newly diagnosed acromegalic patients 1 year after treatment and to determine their mutual relationships.

DESIGN

This prospective study included 30 patients with newly diagnosed acromegaly and 30 healthy controls matched for age, gender, and body mass index. Physical and laboratory examinations, dual-energy X-ray absorptiometry (DXA), and ultrasound evaluations were performed at baseline and 1 year after initial treatment.

RESULTS

The CSA of the median nerve was increased in acromegalic patients compared with controls (13.1 mm² [12.2-14.9] vs 7.5 mm² [6.4-8.4], P < 0.001). One year after treatment of acromegaly, GH and IGF-I levels decreased significantly. The median nerve CSA was significantly reduced after treatment (11.6 mm² [10.2-13.1], P < 0.001). Reduction of IGF-I levels correlated with a decrease in lean mass and increase in fat mass. The median nerve CSA positively correlated with IGF-I levels (R = 0.492, P=0.006) and lean mass (R = 0.419, P=0.021) in acromegalic patients before treatment.

CONCLUSION

This study demonstrates a reduction in the median nerve CSA 1 year after treatment of acromegaly. These changes are closely associated with a reduction in IGF- I levels and in lean body mass. The enlargement of the median nerve in acromegaly can be reversed with adequate treatment.

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.

Ultrasound of the Radial Nerve: A Pictorial Review

This pictorial review focuses on the ultrasound (US) appearance of the normal and pathological radial nerve (RN) and its branches and provides tips with which to locate them and avoid misinterpretation of normal findings. A wide range of our pathological cases are reviewed and presented to help in familiarizing the reader with common and uncommon clinical scenarios that affect the RN and its main branches.

Diagnostic value of median nerve shear wave ultrasound elastography in diagnosis and differentiation of carpal tunnel syndrome severity

Background

Carpal tunnel syndrome (CTS) is the commonest type of peripheral nerve entrapment syndromes. The study aimed at evaluation of diagnostic value of median nerve stiffness measured by shear wave ultrasound elastography for diagnosis and differentiation of CTS severity, correlated to electrophysiological studies. This case–control study involved 40 patients (56 wrists) with CTS of different severity and 40 controls (40 wrists). All participants underwent electrophysiological study to assess the CTS severity, high-resolution conventional B-mode ultrasound to assess cross-sectional area “CSA” of median nerve at carpal tunnel, ratio of median nerve CSA at carpal tunnel and forearm, and shear wave ultrasound elastography with measurement of median nerve mean stiffness and correlation to electrophysiological results as the reference standard.

Results

Mean median nerve stiffness by shear wave US elastography was increased in patients with CTS compared to controls and across the different CTS severity groups (P value < 0.001 & 0.001, respectively). The cutoff value by ROC curve analysis for median nerve stiffness to differentiate between patients with CTS and control group was 65.4 kPa (P value < 0.001, 94.6% sensitivity, 97.3% specificity). Higher diagnostic accuracy was noted with the combination of shear wave elastography and conventional B-mode US with improved AUC (B-mode + shear wave; 0.962, P value < 0.001).

Conclusions

Shear wave ultrasound elastography of median nerve was able to discriminate different severity subgroups of CTS with high sensitivity, while conventional US couldn’t. The diagnostic accuracy of CTS was improved when combined high-resolution conventional B-mode US and complementary shear wave ultrasound elastography.

Cross-Sectional Area Reference Values for Sonography of Peripheral Nerves in Taiwanese Adults

Background: Neuromuscular ultrasound is a complementary technology that aids in the diagnosis of peripheral neuropathy. The interpretation of neuromuscular ultrasound results requires the use of accurate normative cross-sectional area (CSA) reference values. This study aims to provide CSA reference values specific to Taiwanese adults for Sonography of peripheral nerves in the upper and lower extremities.

Methods: The study cohort included 66 healthy subjects (36 women; 30 men). A linear probe was used to measure the CSA of the median, ulnar, radial, tibial, sural, and peroneal nerves at multiple sites. These data were analyzed to determine standard ranges for the CSA at each site (reference range = mean ± 2 × SD) and identify correlations between the CSA and patient characteristics.

Results: Normative CSA ranges were determined for all the assessed nerve sites, revealing that the nerve sizes in this Taiwanese population were smaller than Caucasian populations but comparable to those reported for other Asian cohorts. Men tended to have larger nerves than women, even after adjusting for height and weight. The size of ulnar nerve in the cubital tunnel and the peroneal nerve in the popliteal fossa correlated negatively with increasing age. The nerve size correlated positively with increasing weight and BMI at several sites, correlation of median nerve in the forearm with weight and BMI was significant after multiple testing. Significant correlation was also found between size of ulnar nerve in cubital tunnel and decreasing height.

Conclusion: We provide reference ranges for neuromuscular ultrasound CSA values for the upper and lower extremities that are specific to the Taiwanese population. These reference values may be useful for evaluating peripheral neuropathy in Taiwanese subjects.

Influence of Demographic Factors on Nerve Ultrasound of Healthy Participants in a Multiethnic Asian Population

Background:

High-resolution nerve ultrasound provides morphological information of peripheral nerves. We aimed to determine the normal ultrasonographic reference values of nerve cross-sectional area (CSA) in multiethnic Malaysian healthy participants.

Methods:

Nerve ultrasound of the median, ulnar, radial, tibial, fibular, and sural nerves was performed in 84 healthy participants at anatomical-defined locations. The CSA at each scanned site was measured by tracing circumferentially inside the hyperechoic rim of each nerve. Comparisons were made between genders and ethnic groups. Correlations with age, ethnicity, gender, height, weight, and body mass index (BMI) were evaluated.

Results:

CSA values and reference ranges in healthy participants were generated. Nerve CSA was significantly different in different gender (P = 0.002–0.032) and ethnic groups (P = 0.006–0.038). Men had larger nerve CSA than women, and Malay participants had larger nerve CSA compared to other ethnic groups. Nerve CSA had significant correlations to age, height, weight, and BMI (r = 0.220–0.349, P = 0.001–0.045).

Conclusion:

This study provides normative values for CSA of peripheral nerves in a multiethnic Malaysian population, which serves as reference values in the evaluation of peripheral nerve disorders. The ethnic differences in nerve CSA values should be considered during nerve ultrasound.

Magnetization Transfer Ratio of Peripheral Nerve and Skeletal Muscle : Correlation with Demographic Variables in Healthy Volunteers

Purpose

To assess the correlation of peripheral nerve and skeletal muscle magnetization transfer ratio (MTR) with demographic variables.

Methods

In this study 59 healthy adults evenly distributed across 6 decades (mean age 50.5 years ±17.1, 29 women) underwent magnetization transfer imaging and high-resolution T2-weighted imaging of the sciatic nerve at 3 T. Mean sciatic nerve MTR as well as MTR of biceps femoris and vastus lateralis muscles were calculated based on manual segmentation on six representative slices. Correlations of MTR with age, body height, body weight, and body mass index (BMI) were expressed by Pearson coefficients. Best predictors for nerve and muscle MTR were determined using a multiple linear regression model with forward variable selection and fivefold cross-validation.

Results

Sciatic nerve MTR showed significant negative correlations with age (r = −0.47, p < 0.001), BMI (r = −0.44, p < 0.001), and body weight (r = −0.36, p = 0.006) but not with body height (p = 0.55). The multiple linear regression model determined age and BMI as best predictors for nerve MTR (R² = 0.40). The MTR values were different between nerve and muscle tissue (p < 0.0001), but similar between muscles. Muscle MTR was associated with BMI (r = −0.46, p < 0.001 and r = −0.40, p = 0.002) and body weight (r = −0.36, p = 0.005 and r = −0.28, p = 0.035). The BMI was selected as best predictor for mean muscle MTR in the multiple linear regression model (R² = 0.26).

Conclusion

Peripheral nerve MTR decreases with higher age and BMI. Studies that assess peripheral nerve MTR should consider age and BMI effects. Skeletal muscle MTR is primarily associated with BMI but overall less dependent on demographic variables.

Supplementary Information

The online version of this article (10.1007/s00062-021-01067-5) contains supplementary material, which is available to authorized users.

Reference values for the cross-sectional area of normal radial nerve at two levels using high-resolution ultrasonography

Aim of the study

High-resolution ultrasound is less often used to evaluate the radial nerves. The radial nerve is often involved in entrapment syndromes. The aim of the study is to establish the reference values for the cross-sectional area of the normal radial nerve on high-resolution ultrasonography, and to identify relationships between the cross-sectional area and the subject’s age, gender, height, weight, body mass index, and hand dominance.

Material and methods

The study was conducted on 200 subjects of both sexes, between 18 and 75 years of age, who did not have history of peripheral neuropathy or trauma to the upper limb. High-resolution real-time sonographic examination of the radial nerves was performed in both arms at two different levels. Level 1 was taken just proximal to the nerve bifurcation, and level 2 just after the nerve exits the spiral grove.

Results

The mean cross-sectional area measured at level 2 (4.3 ± 0.4 mm²) was greater than that measured at level 1 (2.3 ± 0.3 mm²). No significant relationship was seen with age and hand dominance (p >0.05), but the cross-sectional area values at above mentioned levels were larger in males than in females (p <0.05). In addition, the cross-sectional areas of the radial nerves showed a positive correlation with height, weight, and body mass index (p <0.05).

Conclusion

The established ultrasonographic reference values along with basic clinical data will aid in the diagnosis, response to treatment, and prognostic evaluation of peripheral neuropathies.

Cross-sectional area reference values for high-resolution ultrasonography of the upper extremity nerves in healthy Asian adults

In this study, multiple-site, cross-sectional area (CSA) reference values were established for major peripheral nerves, including small branches, in the upper extremity of a healthy Asian population.This study included 107 prospectively recruited age-matched, healthy subjects with a mean age of 46 years (range, 24-75 years). All subjects underwent standardized nerve conduction studies for the median, ulnar, peroneal, posterior tibial, and sural nerves. CSA was measured unilaterally at 21 sites of the median, ulnar, radial, posterior interosseous, superficial radial sensory, musculocutaneous, lateral antebrachial cutaneous, and medial antebrachial cutaneous nerves.According to their age, the subjects were assigned to the younger group (20-40 years, n = 40), the middle group (40-59 years, n = 40), and the older group (60-80 years, n = 27). The significant differences of CSA values between age groups were found only at certain sites, such as the median (wrist, P = .003), ulnar (medial epicondyle, P = .031; forearm, P = .022), radial (antecubital fossa, P = .037), and superficial radial sensory nerve (P = .028). The CSA significantly correlated with gender, height, weight, and body mass index.This study provides CSA reference values for nerves, including small sensory nerves in the upper extremity, which can be useful in the ultrasonographic investigation of various peripheral neuropathies in the upper extremity.

Ultrasound-Guided Percutaneous Neuromodulation in Patients with Chronic Lateral Epicondylalgia: A Pilot Randomized Clinical Trial

OBJECTIVE

The aim was to analyze effects of a percutaneous neuromodulation (PNM) treatment on the radial nerve, regarding pain, functionality, electrophysiologic excitability, and morphology, in patients with chronic lateral epicondylalgia (LE).

METHODS

Twenty-four patients with chronic unilateral elbow pain were recruited for this preliminary study and were divided into two groups: control (n = 12) and PNM group (n = 12). The subjects in the PNM group received percutaneous peripheral neurostimulation with an acupuncture needle that was located next to the nerve with ultrasound guidance. Pain using a numerical rating scale (NRS), functional ability using patient-rated tennis elbow evaluation (PRTEE), radial nerve cross-sectional area measured by ultrasound, and chronaxie and accommodation index (AI) measured by the strength-duration curve were evaluated.

RESULTS

Both groups showed no differences in the baseline measurements (all p = 0.001). However, at the end of the treatment, there were significant differences between groups since only the PNM group significantly improved their values compared to their baseline values: level of pain and cross-sectional area (CSA) values showed a significant decrease while the PRTEE scores showed a significant improvement. Then, regarding AI, the PNM group showed significant improvement for the electrophysiologic nerve excitability pattern, reporting normal function in all radial nerves after treatment (p = 0.001). However, chronaxie values always reported similar values with no differences between groups (p >0.05); Conclusion: Ultrasound-PNM technique may be an interesting therapeutic tool for the treatment of chronic LE due to the improvement in the level of pain, functionality, nerve morphology, and excitability in this population.

High resolution ultrasonography of peripheral nerves in diabetic patients to evaluate nerve cross sectional area with clinical profile

OBJECTIVES

The aim of this observational study was ultrasound evaluation of peripheral nerves cross-sectional area (CSA) in subjects with probable diabetic peripheral sensorimotor neuropathy (DPN). CSA was analyzed with reference to clinical and nerve conduction study's (NCS) parameters for early diagnosis and pattern of involvement.

METHODS

A total of 50 patients with probable DPN due to Type 2 diabetes and 50 age-matched healthy controls underwent sonographic examinations of ulnar nerve at the lower arm, median nerve proximal to carpal tunnel, the common peroneal nerve proximal to fibular head, tibial nerve proximal to the tarsal tunnel, and sural nerve at lower third leg.

RESULTS

CSA was increased in cases of DPN as compared to healthy controls. Area changes were more marked with demyelinating pattern. Probable DPN cases with normal NCS had significantly higher number of peripheral nerves showing increased CSA as compared to healthy control. A cut-off of >4 nerve thickening showed a sensitivity of 86 %, and specificity of 56%. The neuropathy pattern in the lower limb was axonal, whereas in the upper limb, it was demyelinating with the majority showing sonographic feature of associated compressive neuropathy.

CONCLUSION

There is an increase in CSA of peripheral nerve in diabetic patients. It can be used as a morphological marker for classifying DPN with changes being picked up earlier to NCS abnormality. Clinical neurological presentation in probable DPN can also be due to compressive neuropathy in early phases, and ultrasound can be a useful tool.

ADVANCES IN KNOWLEDGE

Early pick up of DPN cases shall be useful for early therapy and motivating the patients to actively participate in the treatment. Morphological changes on ultrasonography precedes the electrodiagnostic change in DPN. Symptoms of DPN is not only due to metabolic changes but also compressive neuropathy.

Enhancing diagnostic accuracy using a side-to-side cross-sectional area ratio for the diagnosis of unilateral ulnar mononeuropathy at the elbow

INTRODUCTION

Neuromuscular ultrasonography (NMUS) is a valuable adjunct to electrodiagnostic testing for the diagnosis of entrapment neuropathy. The aim of this study was to determine whether diagnostic accuracy of NMUS could be enhanced in patients with unilateral ulnar mononeuropathy at the elbow (UNE) by utilizing side-to-side ulnar nerve cross-sectional area (CSA) ratios.

METHODS

Retrospective case-control analysis of unilateral UNE cases identified cutoff values for elbow segment ulnar nerve maximum CSA (MCSA) of the symptomatic/asymptomatic limb (M ratio), as well as side-to-side ratios comparing MCSA with ipsilateral CSA at the Guyon canal (E/G), middle forearm (E/F), and middle humerus (E/H). Diagnostic accuracy values were calculated.

RESULTS

The optimal M-ratio cut-off was 1.22 (sensitivity, 92.9%; specificity, 97.8%; accuracy, 95.4%). Optimal cutoffs for inter-E/G, -E/F, and -E/H ratios were 1.07 (sensitivity, 98%; specificity, 78%; accuracy, 87.7%), 1.11 (sensitivity, 95%; specificity, 80%; accuracy, 87.2%), and 1.18 (sensitivity, 95%; specificity, 93%; accuracy, 94%), respectively.

DISCUSSION

The M ratio and inter-E/H ratio exhibited high diagnostic accuracy for unilateral UNE. Prospective studies are needed to compare the accuracy of the new measures with a single MCSA measurement.

Lateral epicondylitis: Are we missing out on radial nerve involvement? A cross-sectional study

INTRODUCTION

Lateral epicondylitis (LE) is a common ailment causing pain and functional limitations. There is an inadequate understanding of its etiopathogenesis. Involvement of the radial nerve (RN) as the primary causative factor for this condition remains debatable. The aim of the present study was to assess the RN thickness in patients with LE and compare it with the unaffected side.

METHODS

The study included seventy eligible patients (M:F, 22:48) in the age group of 30-60 years with a clinical diagnosis of LE. The cross-sectional area of RN was measured at the spiral groove (SG) and around the antecubital fossa (AF) using ultrasound and compared with the unaffected side. Numeric Pain Rating Scale (NPRS) and the QuickDASH scale were used to assess pain and functional impairment.

RESULTS

Thickness of RN at the AF (p = 0.026) and the SG (p = 0.0117) on the affected were statistically significant compared to the unaffected side in the cohort comprising of all the 70 patients. Out of 70 patients, increased thickness was seen in 23 at the SG and 19 at the AF. QuickDASH was statistically significant in patients who had thickened nerves compared to the unaffected side at the SG (p = 0.04) but not at the AF (p = 0.16). NPRS was not statistically significant at either the AF (p = 0.34) or the SG (p = 0.71) in patients with thickened nerves.

CONCLUSION

Tennis elbow needs to be no longer acknowledged only as tendinopathy. It also requires consideration of the involvement of the RN.

Efficacy of a local corticosteroid injection on pain, disability and radial nerve thickness in patients with lateral epicondylitis

Introduction:

The aim of this study was to compare the effect of a steroid injection with conservative therapy (CT) versus CT alone on pain, functional limitations and the cross-sectional area (CSA) of the radial nerve (RN) in patients with lateral epicondylitis (LE).

Methods:

In this clinical trial, seventy subjects in the age group of 30–60 years with a clinical diagnosis of LE were recruited. Patients received an ultrasound-guided steroid injection and CT (Group A, n = 35) or CT alone (Group B, n = 35). Pain intensity (numeric pain rating scale), functional limitations (Quick Disabilities of the Arm, Shoulder, and Hand questionnaire) and the CSA of RN (mm²) using ultrasound were assessed at baseline, 4 and 12 weeks.

Results:

There was a significant difference in pain intensity (P < 0.05) at 4 weeks in favour of Group A but not at 12 weeks. A statistically significant difference was not present favouring either group concerning disability at both the follow-ups. The difference in CSA of the RN at the affected side in both groups A and B was not statistically significant at either the spiral groove or the antecubital fossa at baseline or the subsequent follow-ups.

Conclusions:

The CT with a steroid injection proved to be more efficacious in the short term concerning pain intensity and functional limitations. The RN thickness is not increased in patients with LE, thereby refuting its role to some extent in the pathogenesis of LE.

Neuromuscular Ultrasound in the Pediatric Population

The diagnosis and evaluation of neuromuscular disorders traditionally involves electrodiagnostic (EDx) testing, including nerve conduction studies (NCSs) and electromyography (EMG). These tools can cause pain and discomfort, an important consideration when performed on children. Neuromuscular ultrasound is noninvasive, cost-effective, and increasingly utilized for the detection of neuromuscular pathology. Studies investigating the performance and clinical implementation of ultrasound have primarily been performed in adult populations. Ultrasound in children has the potential to guide EDx testing and ultimately improve diagnostic efficiency and accuracy. This review aims to describe key features of neuromuscular ultrasound in the pediatric population based on the available studies, including our own institutional experience.

Augmented Diagnostic Accuracy of Ultrasonography for Diagnosing Carpal Tunnel Syndrome Using an Optimised Wrist Circumference-Dependent Cross-Sectional Area Equation

Introduction: In diagnosing carpal tunnel syndrome (CTS) there is no consensus about the upper limit of normal (ULN) of the cross-sectional area (CSA) of the median nerve at the carpal tunnel inlet. A previous study showed wrist circumference is the most important independent predictor for the ULN. In this study we optimised a wrist circumference-dependent ULN equation for optimal diagnostic accuracy and compared it to the generally used fixed ULN of 11 mm².

Methods: CSA and wrist circumference were measured in a prospective cohort of 253 patients (clinically defined CTS) and 96 healthy controls. An equation for the ULN for CSA was developed by means of univariable regression analysis. We calculated z-scores for all patients and healthy controls, and analysed these scores in a ROC curve and a decision plot. Sensitivity and specificity were determined and compared to fixed ULN values.

Results: We found augmented diagnostic accuracy of our newly developed equation y = 0.88 ^* x −4.0, where y = the ULN of the CSA and x = wrist circumference. This equation has a corresponding sensitivity and specificity of 75% compared to a sensitivity of 70% while using a fixed cut-off value of 11 mm² (p = 0.015).

Conclusion: Optimising the regression equation for wrist circumference-dependent ULN cross-sectional area of the median nerve at the wrist inlet might improve diagnostic accuracy of ultrasonography in patients with carpal tunnel syndrome and seems to be more accurate than using fixed cut-off values.

Diagnostic utility of median nerve CSA to ulnar nerve CSA ratio in the diagnosis of mild idiopathic carpal tunnel syndrome

Background

Ultrasonography (US) measurement of median nerve cross-sectional area (m-CSA) at pisiform is increasingly utilized in identification of carpal tunnel syndrome (CTS), but there is still no agreement about the ideal cut-off value to employ. The aim of the study was to explore whether the median CSA to ulnar CSA ratio at the level of pisiform may yield a more accurate diagnosis of CTS. The study included 50 patients with mild idiopathic CTS (ICTS), assessed clinically and by nerve conduction studies, and 50 matched controls. M-CSA, median nerve flattening ratio and swelling ratio (m-SR), palmer bowing, and median CSA to ulnar CSA ratio (m-CAS:u-CSA) were measured for patients and controls. The cutoff values for the US parameters for the diagnosis of ICTS were evaluated.

Results

Compared to the control group, the ICTS group had significantly higher m-CSA (p < 0.001), higher m-CSA:u-CSA ratio (p < 0.001), higher m-SR (p = 0.012, and higher palmar bowing (p < 0.001). Use of m-CSA cutoff value of 11.78 mm2 and CSA:u-CSA ratio cut-off point of 2.97 yielded the greatest sensitivity and specificity for the diagnosis of ICTS.

Conclusion

The m-CSA:u-CSA ratio is slightly superior to the m-CSA in the diagnosis of CTS in terms of sensitivity and specificity.

Effects of spasticity and hemiplegic posture on median nerve and carpal tunnel in stroke patients: Electrophysiological and ultrasonographic evaluation

This study aims to evaluate whether the upper extremity spasticity and hemiplegic posture have any effect on the morphology of the carpal tunnel and median nerve in stroke patients. Nerve conduction studies (NCS) were performed in 46 stroke patients and compared to those of 30 healthy controls. The cross-sectional area (CSA) of the carpal tunnel (CT) and median nerve (wrist/mid-forearm levels) was assessed by ultrasonography. The mean ages of the stroke and control group were 55.6 ± 13.5 and 56 ± 12.1 years, respectively. The median spasticity score of the forearm pronators and wrist flexor muscles was 2 (0-4) according to the Modified Ashworth Scale (MAS). The compound muscle action potential (CMAP) of the median nerve was reduced (10,093 ± 4,451 mV) when compared to non-paretic side (11,615 ± 4,397 mV) (p:0.02) and the CSA of the CT was thinner on the paretic side (1.9 ± 0.3 cm² vs 2.08 ± 0.2 cm²) (p:0.03). Pronator spasticity had no significant effect on the CSA of the median nerve and NCS at the forearm level. The CSA of the median nerve at the wrist was significantly thicker in patients with the wrist flexor spasticity graded II (MAS) and above compared to those with spasticity graded I and below (9.5 ± 1.7 mm² and 8.7 ± 1.7 mm² respectively) (p:0.03). However, the thickening of the median nerve didn't cause significant abnormalities in NCS. This study shows that in stroke patients, wrist flexor spasticity and hemiplegic wrist posture can cause explicit morphological changes in the CT and median nerve albeit normal findings on NCS.

Sonographic measurements of normal C5-C8 nerve roots in children

Introduction

The aim of this study was to use ultrasound to measure the cervical nerve roots in normal children to determine normal reference values.

Methods

A total of 441 children of different ages at the Children's Hospital of Chongqing Medical University were examined by ultrasound. The diameter, circumference, and cross‐sectional area of the nerve roots were measured.

Results

Ultrasonographic measurements were consistent with the ranking C5 < C6 < C7. The C8 nerve root was thicker than C7 in 60% of the participants. The nerve root measurements increased with increasing age, height, weight, and body surface area.

Discussion

Normal reference ranges of the cervical nerve roots in children of different ages were established, and can serve as the basis for measurement in future studies.

Nerve ultrasound reference data in children from two to seven years

OBJECTIVE

We examined selected peripheral and spinal nerves of children aged between two and seven years.

METHOD

High resolution ultrasound was performed in 116 children (2-7 years of age) at 19 predefined landmarks of median, ulnar, tibial, fibular, sural and radial nerves, the vagus as well as cervical spinal nerve 5 and 6. Further, side-to-side measuring and grey-scale analysis was done at selected nerve sites.

RESULTS

Nerves of children were on average smaller than those of adults. Nerve growth correlates significantly with age in all nerves, the mean values were similar in the age of two to four years and five to seven years. Body mass index (BMI) and gender showed moderate effect at some nerve sites, however not uniformly in all. A side-to-side difference of up to 30% in median, and up to 20% in tibial nerve can occur in healthy individuals. Grey-scale analysis for echointensity has been performed in median, ulnar and tibial nerves.

CONCLUSION

Nerve size increases with age, BMI and gender have moderate effect. A side-to-side-difference of up to 30% can exist.

SIGNIFICANCE

Reference values of nerve cross-sectional area, side-to-side-difference and echo intensity are necessary to detect nerve pathology in children as well as in adults.

Strength-Duration Curves of Radial Nerve in Patients With Lateral Elbow Pain

CONTEXT

Lateral epicondylalgia (LE) refers to a painful condition at or around the lateral epicondyle of the humerus. LE is one of the most common injuries of the elbow; however, the cause of the pathology is not clear. Patients often experience symptoms consistent with a radial nerve injury; however, data on the involvement of the radial nerve are needed.

OBJECTIVE

To analyze the relationship between electrophysiologic excitability and morphology of the radial nerve in patients with unilateral chronic LE.

DESIGN

Cross-sectional study.

SETTING

Department of Physiotherapy, University of Seville.

PATIENTS

A total of 56 elbows (28 right, 28 left) in 28 patients (12 females, 16 males; age 49 [7.37] y) were recruited by convenience sampling.

MAIN OUTCOME MEASURES

Strength-duration curves (chronaxia and accommodation index) and cross-sectional area (CSA) of the radial nerve were made in all participants. All parameters were compared between both limbs. Also, pain with palpation in the lateral epicondyle and functional pain of involved extremities was assessed using visual analog scale and the Patient-Rated Tennis Elbow Evaluation, respectively.

RESULTS

Symptomatic limb showed higher CSA values of the radial nerve when compared with the asymptomatic limb (P < .001). On the symptomatic limb, duration of symptoms was positively correlated with CSA values. Chronaxia values were all normal and similar between both limbs (P = .35). Regarding accommodation index, 14 (54%) patients showed accommodation indices that suggested pathological radial nerve on the right limb, 4 (14%) on the left limb, 5 (18%) on both limbs, and 4 (14%) had none of the affected nerves. Eight-six percent of patients showed accommodation indices that suggested pathological radial nerve, independently of symptomatic limb. In these cases, affected nerves had higher CSA than the unaffected nerve (P = .01). On the affected nerves, duration of symptoms was positively correlated with accommodation indices.

CONCLUSIONS

These findings suggest that patients with unilateral chronic LE show a decreased excitability in any radial nerve, independently of the symptomatic limb, and that pathological nerves have higher CSA than the nonpathological nerves.

Ratio and difference of the cross-sectional area of median nerve to ulnar nerve in diagnosing carpal tunnel syndrome: a case control study

Background

To evaluate the diagnostic accuracy of the median-to-ulnar nerve ratio (MUR) and the median-to-ulnar nerve difference (MUD) in patients with carpal tunnel syndrome (CTS).

Methods

In this study, 32 patients with CTS and 32 healthy volunteers were evaluated. All participants received a series of tests and ultrasound examination for the evaluation of the following criteria: cross-sectional area of the median nerve at the pisiform level (CSA-P), swelling ratio (SR), MUR, MUD, and flattening ratio (FR).

Results

CSA-P, SR, MUR, and MUD were all significantly larger in the patients with CTS than in the healthy volunteers. The areas under the receiver operator characteristic curves of MUD, MUR, CSA-P, and SR were 0.78, 0.75, 0.70, and 0.61 respectively. MUD had higher sensitivity (84%) than MUR, CSA-P, and SR (sensitivity: 63, 63, and 53%, respectively).

Conclusions

By using the ulnar nerve area at the pisiform level as an internal control parameter, the MUD and MUR methods showed higher diagnostic accuracy than SR in patients with CTS. Further application of these methods in research and clinical settings is recommended.

Trial registration

Clinicaltrial.gov NCT03033173. Registered 18 January 2017. Retrospectively registered.

Evaluation of radial nerve continuity early after humeral shaft fracture fixation using high-resolution nerve ultrasonography: a pilot study of feasibility

BACKGROUND

This study evaluated the feasibility and reliability of high-resolution ultrasonography (HRUS) of the radial nerve in the early, postoperative period after operative stabilization of humeral shaft fractures.

METHODS

This study enrolled patients between September 2015 and April 2018 with a humeral shaft fracture who were assessed with HRUS within 2 weeks after surgery. Based on the ultrasound artifacts, the examiners subjectively defined quality of ultrasound as "bad" or "good." The cross-sectional area of the radial and the posterior interosseous nerve was recorded at predefined locations. The radial nerve was scanned axially in the whole course to identify nerve continuity.

RESULTS

Of 44 patients who underwent operations for humeral shaft fracture, HRUS was used to assess 15 patients at an average 4.8 ± 2.6 days (range, 2-11 days) after surgery. The examiners defined ultrasound quality as "good" in 13 of 15 patients (~87%). Primary radial nerve palsy (RNP) was identified in 3 of the 15 patients, and 4 sustained secondary RNP. Nerve continuity was demonstrated by HRUS in every patient. In patients with RNP, nerve continuity was secondarily confirmed by surgical exploration or functional and electrophysiological recovery.

CONCLUSION

Early postoperative HRUS of the radial nerve after osteosynthesis of humeral shaft fractures is a feasible and reliable method to identify radial nerve continuity. In case of pathology, this assessment tool can additionally provide valuable information concerning location and etiology of the RNP.

The Use of Neuromuscular Ultrasound and NCS/EMG Testing in the Differential Diagnosis of Carpal Tunnel Syndrome and Radiculopathy

BACKGROUND AND PURPOSE

The Neuromuscular ultrasound and Nerve conduction studies/Electromyography (NCS/EMG) are valuable diagnostic tools that examine and diagnose several nerve problems. The purpose of this case report is to describe a diagnostic electrophysiologic evaluation that differentiates between carpal tunnel syndrome (CTS) and radiculopathy in very mild or early stage cases.

CASE DESCRIPTION

The patient was a 30-year-old woman who sustained a tingling sensation in the second and third digits of her left hand, radiating pain in her left upper extremity and occasional neck pain. The patient cannot determine whether her radiating pain starts from the neck to her hand or starts from her hand up to the neck. Physical examination was not conclusive. Neuromuscular ultrasound and NCS/EMG were used to assess the median nerve at the carpal tunnel and the C6-7 nerve roots. A proof of the median nerve injury at the wrist was confirmed. The patient was treated with a night wrist splint.

OUTCOMES

The patient's symptoms were diminished after the use of the night splint for a period of approximately 4 weeks. A follow-up electrodiagnostic evaluation reveals improvement compared to the previous data with no electrophysiologic evidence of a current nerve injury status.

DISCUSSION

Neuromuscular ultrasound and NCS/EMG combined techniques helped in the differential diagnosis between CTS and C6-7 nerve roots radiculopathy. In this case, physical examination could not give an immediate conclusive answer.